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Sample records for dien bien phu

  1. Crystal structure of the Pseudomonas aeruginosa cytoplasmic heme binding protein, Apo-PhuS.

    PubMed

    Tripathi, Sarvind; O'Neill, Maura J; Wilks, Angela; Poulos, Thomas L

    2013-11-01

    Iron is an essential element to all living organisms and is an important determinant of bacterial virulence. Bacteria have evolved specialized systems to sequester and transport iron from the environment or host. Pseudomonas aeruginosa, an opportunistic pathogen, uses two outer membrane receptor mediated systems (Phu and Has) to utilize host heme as a source of iron. PhuS is a 39 kDa soluble cytoplasmic heme binding protein which interacts and transports heme from the inner membrane heme transporter to the cytoplasm where it is degraded by heme oxygenase thus releasing iron. PhuS is unique among other cytoplasmic heme transporter proteins owing to the presence of three histidines in the heme binding pocket which can potentially serve as heme ligands. Out of the three histidine residues on the heme binding helix, His 209 is conserved among heme trafficking proteins while His 210 and His 212 are unique to PhuS. Here we report the crystal structure of PhuS at 1.98Å resolution which shows a unique heme binding pocket and oligomeric structure compared to other known cytoplasmic heme transporter and accounts for some of the unusual biochemical properties of PhuS. PMID:23973453

  2. A Conversation with Zoltan P. Dienes

    ERIC Educational Resources Information Center

    Sriraman, Bharath; Lesh, Richard

    2007-01-01

    The name of Zoltan P. Dienes (1916- ) stands with those of Jean Piaget, Jerome Bruner, Edward Begle, and Robert Davis as a legendary figure whose work left a lasting impression on the field of mathematics education. Dienes' name is synonymous with the multibase blocks that he invented for the teaching of place value. Among numerous other things,…

  3. Predictors for dioxin accumulation in residents living in Da Nang and Bien Hoa, Vietnam, many years after Agent Orange use.

    PubMed

    Pham, Diem T; Nguyen, Hang M; Boivin, Thomas G; Zajacova, Anna; Huzurbazar, Snehalata V; Bergman, Harold L

    2015-01-01

    Agent Orange (AO) was the main defoliant used by the US in Vietnam from 1961 to 1971; AO was contaminated with dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD). Three major dioxin “hot spots” remain from previous AO storage and use at former US bases at Bien Hoa, Da Nang, and Phu Cat, posing potential health risks for Vietnamese living on or near these hot spots. We evaluated potential risk factors contributing to serum TCDD levels in Vietnamese residents at and near contaminated sites in Da Nang and Bien Hoa, Vietnam. We used multiple linear regression to analyze possible associations of blood dioxin concentrations with demographic, socioeconomic, lifestyle, and dietary risk factors for residents living on or near these hot spots. For the Da Nang study, fish farming on the site, living on property flooded from monsoon rains, and age were among the factors showing significant positive associations with serum TCDD concentrations. For the Bien Hoa study, fish farmers working at this site and their immediate family members had significantly higher serum TCDD concentrations. Our results suggest that water-related activities, especially fish-farming, at the hot spots increased the risk of exposure to dioxin. PMID:25463251

  4. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H.; Watkins, J.S.

    1996-12-31

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  5. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H. ); Watkins, J.S. )

    1996-01-01

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  6. Spectroscopic Determination of Distinct Heme Ligands in Outer-Membrane Receptors PhuR and HasR of Pseudomonas aeruginosa

    PubMed Central

    Smith, Aaron D.; Modi, Anuja R.; Sun, Shengfang; Dawson, John H.; Wilks, Angela

    2015-01-01

    Pseudomonas aeruginosa PAO1 encodes two outer membrane receptors, PhuR (Pseudomonas heme uptake) and HasR (heme assimilation system). The HasR receptor acquires heme through interaction with a secreted hemophore, HasAp. The non-hemophore-dependent PhuR is encoded along with proteins required for heme translocation into the cytoplasm. Herein, we report the isolation and characterization of the HasR and PhuR receptors. Absorption and MCD spectroscopy confirmed that, similar to other Gram-negative OM receptors, HasR coordinates heme through the conserved N-terminal plug His-221 and His-624 of the surface-exposed FRAP-loop. In contrast, PhuR showed distinct absorption and MCD spectra consistent with coordination through a Tyr residue. Sequence alignment of PhuR with all known Gram-negative OM heme receptors revealed a lack of a conserved His within the FRAP loop but two Tyr residues at positions 519 and 529. Site-directed mutagenesis and spectroscopic characterization confirmed Tyr-519 and the N-terminal plug His-124 provide the heme ligands in PhuR. We propose that PhuR and HasR represent nonredundant heme receptors capable of sensing and accessing heme across a wide range of physiological conditions on colonization and infection of the host. PMID:25849630

  7. A new species of Dixonius (Squamata: Gekkonidae) from Phu Quy Island, Vietnam.

    PubMed

    Botov, Andreas; Phung, Trung My; Nguyen, Truong Quang; Bauer, Aaron M; Brennan, Ian G; Ziegler, Thomas

    2015-01-01

    We describe a new species of Dixonius on the basis of five specimens from Phu Quy Island, Binh Thuan Province, in southern Vietnam. The new species can be distinguished from congeners based on molecular and morphological differences. Diagnostic features are: small size (SVL up to 44 mm); 7 or 8 supralabials; 11 or 12 rows of keeled tubercles on dorsum; 21-23 ventral scale rows; 5 or 6 precloacal pores in males; a canthal stripe running from rostrum through the eye and terminating behind the head; second pair of postmentals about one third to one half size of first pair; ground color of dorsum brown, with one or two rows of light yellow or orange spots in one or two rows along flanks, and irregular bands or a reticulated network of dark marks on dorsum. This is the fifth species of Dixonius known to occur in Vietnam. PMID:26624650

  8. Vietnam: An Historical Perspective.

    ERIC Educational Resources Information Center

    Shackford, Julie

    This book provides an overview of Vietnam's history prior to the U.S. presence there. The book begins with a chronology extending from prehistoric times to the defeat of the French at Dien Bien Phu in 1954. Each chapter provides background information along with a glossary, student activities, and project suggestions. Chapters include: (1)…

  9. Syntheses and properties of poly([6. 2]cyclophane-1,5-diene)s: Electroactive polymers

    SciTech Connect

    Guerrero, D.J.

    1993-01-01

    The synthesis and characterization of (E,E)-[6.2]-(2,5)thiophenophane-1,5-diene (2) is described. Ultraviolet and variable temperature [sup 1]H-nmr spectroscopy were used to deduce structural detail of 2 in solution. Cationic cyclopolymerization of 2 gave polymer 3 which has bridged thiophene rings pendant to the polymer backbone. Structural details of polymer 3 are largely based on comparison with its known benzene analogue (1), poly(2-vinylthiophene) (15) and poly(5-methyl-2-vinylthiophene) (17). The thermal and electronic properties of polymer 3 were compared to those of 15. Polymer 3 exhibited conductivity in the 10[sup [minus]3]-10[sup [minus]4] S/cm range when exposed to iodine vapor. Apparent energies of activation for conductivity in iodine saturated polymers 3 and 15 were calculated from conductivity temperature dependence measurements. Differences in conductivity behavior for iodine saturated polymers 1, 3, and 15 are discussed in terms of both charge generation and mobility. The effects of increasing the electric field on photoconductivity and mobility of 1 and 3 are discussed. Utilization of 1 and 3 in the construction of polymer based chemical sensors for iodine is demonstrated. A novel iodine promoted ring opening polymerization of [2,2]-(2,5)thiophenophane (TPP) is presented. Ft-ir studies of the resulting films revealed formation of a poly ((2,5)-thienylene ethylene) type structure. [2.2]-(2,5)-furanophane and [2.2]-(9,10)-anthracenophane treated similarly also gave the corresponding poly(arylene ethylene) polymers. [2.2]paracyclophane, 4-nitro-[2.2]paracyclophane, anti-[2.2]-(1,4)-naphthalenophane and (E,E)-[6.2]paracyclophane-1,5-diene did not give polymer in the presence of iodine. Electrochemical ring opening polymerization of TPP at a Pt anode suggests a radical cationic intermediate during polymerization.

  10. Integration ofhup cosmid pHU52 into the chromosomal DNA ofCicer-Rhizobium using Tn5 as an homologous sequence.

    PubMed

    Kunnimalaiyaan, M; Lodha, M L; Sreekumar, K R

    1992-11-01

    Cosmid pHU52, which carrieshup genes ofBradyrhizobium japonicum, has been integrated into theCicer-Rhizobium G36-84 genome via Tn5-mediated homologous recombination. Tn5 was inserted into both the cosmid pHU52 and the chromosome ofCicer-Rhizobium to provide a region of DNA homology, without affecting the expression of necessary genes. An incompatible plasmid, pPH1JI, was used to select those few cells that had undergone recombination. The integration of the cosmid was demonstrated by Southern blot analysis. Chromosomal integration of thehup genes maximized stability and minimized the potential for their horizontal transfer to other bacterial species. The integratedhup genes were found to expressex planta as well in nodules. The method described illustrates how a given gene can be stably integrated into the chromosome. PMID:24425601

  11. Palladium-catalysed hydroamidocarbonylation of 1,3-dienes.

    PubMed

    Li, Haoquan; Fang, Xianjie; Jackstell, Ralf; Neumann, Helfried; Beller, Matthias

    2016-06-01

    Herein, we report our recent result on the development of the selective catalytic method towards the synthesis of β,γ-unsaturated imides via Pd-catalysed hydroamidocarbonylation of conjugated dienes. Note that this reaction proceeds under acid additive free conditions. Various dienes, including those of high industrial value (e.g. isoprene, 1,3-butadiene), are shown to be compatible with our established method (28 examples, 40-99% yield), which leads to the corresponding β,γ-unsaturated imides in a highly efficient and atom-economic fashion. PMID:27169986

  12. Alkyl substituted [2.2]paracyclophane-1,9-dienes.

    PubMed

    Lidster, Benjamin J; Kumar, Dharam R; Spring, Andrew M; Yu, Chin-Yang; Helliwell, Madeleine; Raftery, James; Turner, Michael L

    2016-07-01

    [2.2]Paracyclophane-1,9-dienes substituted with n-octyl chains have been synthesised from the corresponding dithia[3.3]paracyclophanes using a benzyne induced Stevens rearrangement. The use of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate and tetra-n-butylammonium fluoride as the in situ benzyne source gave significantly improved yields over traditional sources of benzyne and enabled the preparation of n-octyl substituted [2.2]paracyclophane-1,9-dienes on a multi-gram scale. PMID:27249777

  13. Process for crosslinking and extending conjugated diene-containing polymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

    1977-01-01

    A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

  14. Recent advances in stereoselective synthesis of 1,3-dienes.

    PubMed

    De Paolis, Michael; Chataigner, Isabelle; Maddaluno, Jacques

    2012-01-01

    The aim of this review is to present the latest developments in the stereoselective synthesis of conjugated dienes, covering the period 2005-2010. Since the use of this class of compounds is linked to the nature of their appendages (aryls, alkyls, electron-withdrawing, and heterosubstituted groups), the review has been categorized accordingly and illustrates the most representative strategies and mechanisms to access these targets. PMID:22527407

  15. The origin and evolution of skarn-forming fluids from the Phu Lon deposit, northern Loei Fold Belt, Thailand: Evidence from fluid inclusion and sulfur isotope studies

    NASA Astrophysics Data System (ADS)

    Kamvong, Teera; Zaw, Khin

    2009-05-01

    The Phu Lon skarn Cu-Au deposit is located in the northern Loei Fold Belt (LFB), Thailand. It is hosted by Devonian volcano-sedimentary sequences intercalated with limestone and marble units, intruded by diorite and quartz monzonite porphyries. Phu Lon is a calcic skarn with both endoskarn and exoskarn facies. In both skarn facies, andradite and diopside comprise the main prograde skarn minerals, whereas epidote, chlorite, tremolite, actinolite and calcite are the principal retrograde skarn minerals. Four types of fluid inclusions in garnet were distinguished: (1) liquid-rich inclusions; (2) daughter mineral-bearing inclusions; (3) salt-saturated inclusions; and (4) vapor-rich inclusions. Epidote contains only one type of fluid inclusion: liquid-rich inclusions. Fluid inclusions associated with garnet (prograde skarn stage) display high homogenization temperatures and moderate salinities (421.6-468.5 °C; 17.4-23.1 wt% NaCl equiv.). By contrast, fluid inclusions associated with epidote (retrograde skarn stage) record lower homogenization temperatures and salinities (350.9-399.8 °C; 0.5-8 wt% NaCl equiv.). These data suggest a possible mixing of saline magmatic fluids with external, dilute fluid sources (e.g., meteoric fluids), as the system cooled. Some fluid inclusions in garnet contain hematite daughters, suggesting an oxidizing magmatic environment. Sulfur isotope determinations on sulfide minerals from both the prograde and retrograde stages show a uniform and narrow range of δ34S values (-2.6 to -1.1 ‰ δ34S), suggesting that the ore-forming fluid contained sulfur of orthomagmatic origin. Overall, the Phu Lon deposit is interpreted as an oxidized Cu-Au skarn based on the mineralogy and fluid inclusion characteristics.

  16. Rapid assembly of structurally defined and highly functionalized conjugated dienes via tethered enyne metathesis.

    PubMed

    Yao, Q

    2001-06-28

    [reaction: see text] Conjugated dienes are versatile building blocks in organic synthesis, and the development of new methods for their synthesis remains an important topic in modern synthetic organic chemistry. We describe here an expedient synthesis of highly functionalized conjugated dienes through sequential silicon-tethered ring-closing enyne metathesis mediated by Grubbs' Ru carbene catalysts and Tamao oxidation. Notable attributes of this methodology include short synthetic manipulations and the structural complexity it confers on the resulting diene moiety. PMID:11418051

  17. An efficient, overall [4+1] cycloaddition of 1,3-dienes and nitrene precursors.

    PubMed

    Wu, Qiong; Hu, Jian; Ren, Xinfeng; Zhou, Jianrong

    2011-10-01

    Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3-pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate ([Cu(hfacac)(2)]). The method is applicable to a wide array of dienes with good yields. When 1,4-disubstituted dienes are used as substrates, good-to-excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)(2)] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst. PMID:21887836

  18. Synthesis, characterization, and reactivity of ruthenium diene/diamine complexes including catalytic hydrogenation of ketones.

    PubMed

    Morilla, M Esther; Rodríguez, Pilar; Belderrain, Tomas R; Graiff, Claudia; Tiripicchio, Antonio; Nicasio, M Carmen; Pérez, Pedro J

    2007-10-29

    Thermal reactions between [RuCl2(diene)]n (diene = 2,5-norbornadiene, nbd; 1,5-cyclooctadiene, cod) with an excess of N,N,N',N'-tetramethylethylene diamine (tmeda) afforded derivatives [RuCl2(diene)(tmeda)] (diene = nbd, 1; cod, 2) as a mixture of cis and trans isomers. When thermolysis was performed under H2 mixtures of hydride species [RuCl(H)(diene)(tmeda)] (diene = nbd, 3; cod, 4) and the bis-tmeda adduct trans-[RuCl2(tmeda)2] (5) were obtained in different ratios depending upon the reaction conditions and reaction times. Heating polymeric Ru(II) precursors in toluene in the presence of a 5-fold excess of the bulkier N,N,N',N'-tetraethylethylene diamine (teeda) resulted in a rare diamine dealkylation process with formation of trans-[RuCl2(nbd)(Et2NCH2CH2NHEt)] (6) and trans-[RuCl2(cod)(EtHNCH2CH2NHEt)] (7) in high yields. The presence of N-H functionalities in the coordinated diamine ligands of 6 and 7 was unambiguously established by single-crystal X-ray diffraction studies. The dealkylation process of the teeda ligand seems to proceed intramolecularly as shown by solution NMR studies performed with the soluble Ru(II) precursors trans-[RuCl2(amine)2(diene)] (diene = nbd, amine = morpholine, 9; diene = cod, amine = Et2NH, 10). The above complexes [RuCl2(diene)(diamine)] have been tested as precatalysts in the hydrogenation of ketones both for transfer as well as direct hydrogenation, the latter route being the most effective. PMID:17900107

  19. Recent Applications of Acyclic (Diene)iron Complexes and (Dienyl)iron Cations in Organic Synthesis

    PubMed Central

    Chaudhury, Subhabrata

    2009-01-01

    Complexation of (tricarbonyl)iron to an acyclic diene serves to protect the ligand against oxidation, reduction and cycloaddition reactions while the steric bulk of this adjunct serves to direct the approach reagents to unsaturated groups attached to the diene onto the face opposite to iron. Furthermore, the Fe(CO)3 moiety can serve to stabilize carbocation centers adjacent to the diene (i.e. pentadienyl-iron cations). Recent applications of these reactivities to the synthesis of polyene, cyclopropane, cycloheptadiene and cyclohexenone containing natural products or analogs will be presented. PMID:21709767

  20. Description of the tadpoles of two endemic frogs: the Phu Luang cascade frog Odorrana aureola (Anura: Ranidae) and the Isan big-headed frog Limnonectes isanensis (Anura: Dicroglossidae) from northeastern Thailand.

    PubMed

    Ampai, Natee; Rujirawan, Attapol; Arkajag, Jirachai; Mcleod, David S; Aowphol, Anchalee

    2015-01-01

    We describe the external morphology of the tadpoles of two frogs endemic to Thailand: the Phu Luang cascade frog    (Odorrana aureola) and the Isan big-headed frog (Limnonectes isanensis) from the type localities in the Phu Luang Wildlife Sanctuary, Loei Province, northeastern Thailand. Morphological and genetic characters (16S rRNA) were used to identify specimen and match tadpoles to the adults. Detailed descriptions of external morphology and coloration in life are provided for both species. We provide a brief discussion of the ecology of these tadpoles and a comparison to previously published data from tadpoles of closely related taxa. Additionally, we provide evidence for the utility of larval morphology in resolving the taxonomic puzzles presented by cryptic species complexes. PMID:26250010

  1. Substitution effect on the cylization/fluorination reaction of N-dienes in superacid.

    PubMed

    Vardelle, Emilie; Martin-Mingot, Agnès; Jouannetaud, Marie-Paule; Bachmann, Christian; Marrot, Jérôme; Thibaudeau, Sébastien

    2009-08-21

    The novel cyclization/fluorination reaction of N-dienes in superacid was extended to substituted substrates. The influence of the substitution on superelectrophilic character of dicationic intermediates was shown and its dramatic effect on the synthesis of fluoropiperidines was studied. On the basis of new dicationic alpha-chloronium ammonium intermediates, starting from halogen-substituted dienes, high-valued fluorinated piperidines were synthesized. PMID:19588903

  2. Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

    PubMed Central

    Röse, Philipp; Emge, Steffen; Yoshida, Jun-ichi

    2015-01-01

    Summary The cobalt(I)-catalysed 1,4-hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran and pyran derivatives under indirect electrochemical conditions generating selenium or iodonium cations. The reactions proceed in good yields and regioselectivities for the formation of single diastereomers. PMID:25815067

  3. Spiro[2.4]hepta-4,6-dienes: synthesis and application in organic synthesis

    NASA Astrophysics Data System (ADS)

    Menchikov, L. G.; Nefedov, O. M.

    2016-03-01

    This review integrates and describes systematically the data in the field of spiro[2.4]hepta-4,6-dienes published in the past 15 years. The changes in the development of studies that took place during this period are noted. The methods for the synthesis, the reactivity details and key chemical transformations of spiro[2.4]hepta-4,6-dienes are considered, with the emphasis on applications of these compounds in organic synthesis. The bibliography includes 207 references.

  4. Non-Planar Structures of the High-Energy Rotational Conformers of 2-METHYLBUTA-1,3-DIENE (isoprene) and 2,3-DIMETHYLBUTA-1,3-DIENE

    NASA Astrophysics Data System (ADS)

    Panchenko, Yu. N.; Bock, Ch. W.; Larkin, J. D.; Abramenkov, A. V.; Kühnemann, F.

    2009-06-01

    Optimization of the geometrical parameters and determination of the force fields for rotamers of the title molecules were performed at the MP2(FC)/aug-cc-pVDZ//MP2(FC)/aug-cc-pVDZ computational level. The vibrational analyses of these conformers were carried out using scaled quantum-mechanical force field methodology. Recent experimental wavenumbers for these conformers and their deuteroisomers were incorporated into these analyses. The theoretical non-planar structures of the high-energy conformers of 2-methylbuta-1,3-diene (isoprene) and 2,3-dimethylbuta-1,3-diene were corroborated by good agreement between the experimental and theoretical wavenumbers of the molecules under investigation. The dihedral angles of the non-planar high-energy conformers for rotation around the =C-C= bond are as follows: 41.6^° for 2-methylbuta-1,3-diene (isoprene) and 47.0^° for 2,3-dimethylbuta-1,3-diene. Previous studies performed at the HF/6-31G level gave 41.0^° and 48.5^° for the first and second compounds, respectively. Yu. N. Panchenko, Ch. W. Bock, J. D. Larkin, A. V. Abramenkov, F. Kühnemann, Struct. Chem. 19, 421 (2008). Yu. N. Panchenko, Ch. W. Bock, J. D. Larkin, A. V. Abramenkov, Struct. Chem. 19, 793 (2008)

  5. Solvent-free cyclization of linear dienes using olefin metathesis and the Thorpe-Ingold effect

    SciTech Connect

    Forbees, M.D.E.; Myers, T.L.; Maynard, H.D.; Schulz, G.R. ); Patton, J.T.; Smith, D.W. Jr.; Wagener, K.B. )

    1992-12-30

    The olefin metathesis reaction is of great synthetic utility in polymer chemistry. The recent development of ring-opening (ROMP) and acyclic diene (ADMET) metathesis polymerization reactions has opened new avenues for the synthesis of novel polymeric materials. Recently the authors used ADMET to synthesize several photochemically active poly(keto olefins) using the catalyst Mo(CHCMe[sub 2]Ph)(NAr)(OCMe(CF[sub 3])[sub 2])[sub 2] (Ar = 2,6-diisopropylphenyl) (1) developed by Schrock and co-workers in 1990. In the course of that work, they discovered that neat samples of highly substituted dienes will cyclize quantitatively via metathesis to give difunctional five- and seven-membered rings instead of the expected linear polymer. Examples of substituted diene cyclizations by metathesis even in the presence of a solvent are rare. Their systematic exploitation in organic synthesis has therefore been limited to two recent studies by Fu and Grubbs, who cyclized several substituted diene ethers, amines, and amides to unsaturated oxygen and nitrogen heterocycles. Cyclization of unsubstituted dienes in various solvents has been reported, but complete conversion occurred in only a few cases. Formation of cyclic alkene oligomers from back-biting during the ROMP reaction is also known. The reactions reported here are unusual in that they are intermolecular between catalyst and substrate, yet can give 100% yield of product solely from the monomer in the absence of solvent. 13 refs.

  6. Reversal of the Regiochemistry in the Rhodium-Catalyzed [4+3] Cycloaddition Between Vinyldiazoacetates and Dienes

    PubMed Central

    Guzmán, Pablo E.; Lian, Yajing

    2015-01-01

    A regio-, diastereo- and enantioselective [4+3] cycloaddition between vinylcarbenes and dienes has been achieved using the dirhodium tetracarboxylate catalyst Rh2(S-BTPCP)4. This methodology provides facile access to 1,4-cycloheptadienes that are regioisomers of those formed from the tandem cyclopropanation/Cope rearrangement reaction of vinylcarbenes with dienes. PMID:25266984

  7. Anomalous Reactivity and Selectivity in the Intermolecular Diels-Alder Reactions of Multisubstituted Acyclic Dienes with Geometrical Isomers of Enals.

    PubMed

    Zhou, Jia-Hui; Cai, Sai-Hu; Xu, Yun-He; Loh, Teck-Peng

    2016-05-20

    A Lewis-acid catalyzed intermolecular Diels-Alder reaction between multisubstituted acyclic dienes and the E and Z isomers of α,β-enals was studied. It was found that the diene reacted selectively with the Z-isomer of the α,β-enal. PMID:27132468

  8. Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

    PubMed Central

    Eberlin, Ludovic; Tripoteau, Fabien; Carreaux, François

    2014-01-01

    Summary In the last few years, multicomponent reactions involving boron substituted 1,3-dienes have emerged as important tools in synthetic organic chemistry. The most significant recent results and developments obtained in this area are reported in this review. PMID:24605143

  9. The stereoselective synthesis of dienes through dehalogenative homocoupling of terminal alkenyl bromides on Cu(110).

    PubMed

    Sun, Qiang; Cai, Liangliang; Ma, Honghong; Yuan, Chunxue; Xu, Wei

    2016-05-21

    We have successfully achieved the stereoselective synthesis of a specific cis-diene moiety through a dehalogenative homocoupling of alkenyl bromides on the Cu(110) surface, where the formation of a cis-form organometallic intermediate is the key to such a stereoselectivity as determined by DFT calculations. PMID:27063567

  10. Implicit Learning of Nonlocal Musical Rules: A Comment on Kuhn and Dienes (2005)

    ERIC Educational Resources Information Center

    Desmet, Charlotte; Poulin-Charronnat, Benedicte; Lalitte, Philippe; Perruchet, Pierre

    2009-01-01

    In a recent study, G. Kuhn and Z. Dienes (2005) reported that participants previously exposed to a set of musical tunes generated by a biconditional grammar subsequently preferred new tunes that respected the grammar over new ungrammatical tunes. Because the study and test tunes did not share any chunks of adjacent intervals, this result may be…

  11. A New Steroidal 5,7-Diene Derivative, 3β-Hydroxyandrosta-5, 7-Diene-17β-Carboxylic Acid, Shows Potent Anti-proliferative Activity

    PubMed Central

    Kim, Tae-Kang; Chen, Jianjun; Li, Wei; Zjawiony, Jordan; Miller, Duane; Janjetovic, Zorica; Tuckey, Robert C; Slominski, Andrzej

    2010-01-01

    The new steroidal 5,7-diene, 3β-hydroxyandrosta-5,7-diene-17β-carboxylic acid (17-COOH-7DA), was synthesized from 21-acetoxypregnenolone, with the oxidative cleavage of the side chain being dependent on the presence of oxygen. In human epidermal (HaCaT) keratinocytes, 17-COOH-7DA inhibited proliferation in a dose-dependent manner, starting at a dose as low as 10−11 M. This inhibition was accompanied by decreased expression of epidermal growth factor receptor, bcl2 and cyclin E2 mRNAs and by increased expression of involucrin mRNA. Inhibition of proliferation was associated with slowing of the cell cycle in G1/G0 phases but not with cell death. 17-COOH-7DA was significantly more potent than pregnenolone, 17-COOH-pregnenolone, 17-COOCH3-7DA and calcitriol. 17-COOH-7DA also inhibited proliferation of normal human epidermal melanocytes and human and hamster melanoma lines, however, with lower potency than for keratinocytes. In normal human dermal fibroblasts 17-COOH-7DA stimulated proliferation in serum-free media but inhibited it in the presence of 5% serum. 17-COOH-7DA inhibited cell colony formation of human and hamster melanoma cells, and induced monocyte-like differentiation of human HL60 leukemia cells. Thus, the new steroidal 5,7-diene, 17-COOH-7DA, can serve as an inhibitor of proliferation of normal keratinocytes and normal and malignant melanocytes, as a condition-dependent regulator of fibroblast proliferation and a stimulator of leukemia cell differentiation. PMID:20025893

  12. "On Water" Organocatalyzed [4 + 2] Cycloaddition of Enones and Nitro Dienes for the Enantioselective Synthesis of Densely Substituted Cyclohexanones.

    PubMed

    Vamisetti, Ganga B; Chowdhury, Raghunath; Kumar, Mukesh; Ghosh, Sunil K

    2016-05-01

    An "on water" hydroquinine-based primary amine-benzoic acid organocatalyst system was found to be best suited to produce 3,4,5-trisubstituted cyclohexanones with a nitro group in the 4-position from enones and nitro dienes under ambient conditions in good yield, with good diastereoselectivity, and with excellent enantioselectivity. An appreciable rate enhancement by water was observed compared to organic solvents. Mechanistic analysis of the reaction suggests that it followed an endo [4 + 2] cycloaddition with enamine of enone as diene and nitro diene as dienophile. PMID:27120404

  13. Effects of diene valepotriates from Valeriana glechomifolia on Na+/K+-ATPase activity in the cortex and hippocampus of mice.

    PubMed

    Müller, Liz G; Salles, Luisa; Lins, Helena A; Feijó, Priscilla R O; Cassel, Eduardo; Vargas, Rubem; von Poser, Gilsane L; Noël, François; Quintas, Luis E M; Rates, Stela M K

    2015-02-01

    Diene valepotriates obtained from Valeriana glechomifolia present antidepressant-like activity, mediated by dopaminergic and noradrenergic neurotransmissions. Also, previous studies have shown inhibitory activity of diene valepotriates towards Na(+)/K(+)-ATPase from the rat brain in vitro. Nevertheless, in vivo studies regarding the action of diene valepotriates on this enzyme are still lacking. Considering that Na(+)/K(+)-ATPase cerebral activity is involved in depressive disorders, the aim of this study was to investigate the effects of acute (5 mg/kg, p. o.) and repeated (5 mg/kg, p. o., once a day for three days) diene valepotriate administration on Na(+)/K(+)-ATPase activity in the cortex and hippocampus of mice submitted or not submitted to the forced swimming test. In addition, the protein expression of Na(+)/K(+)-ATPase α1, α2, and α3 isoforms in the cortex of mice repeatedly treated with diene valepotriates (and submitted or not submitted to the forced swimming test) was investigated. Diene valepotriates significantly decreased mice immobility time in the forced swimming test when compared to the control group. Only the animals repeatedly treated with diene valepotriates presented increased Na(+)/K(+)-ATPase activity in the cerebral cortex, and the exposure to the forced swimming test counteracted the effects of the diene valepotriates. No alterations in the hippocampal Na(+)/K(+)-ATPase activity were observed. Repeated diene valepotriate administration increased the cortical content of the α2 isoform, but the α3 isoform protein expression was augmented only in mice repeatedly treated with diene valepotriates and forced to swim. Mice treated with the vehicle and submitted to the forced swimming test also presented an increase in the content of the α2 isoform, but no alterations in Na(+)/K(+)-ATPase activity. These results suggest that cortical Na(+)/K(+)-ATPase may represent a molecular target of the diene valepotriates in vivo and long

  14. Regio- and Stereoselective Monoepoxidation of Dienes using Methyltrioxorhenium: Synthesis of Allylic Epoxides

    PubMed Central

    2015-01-01

    Methyltrioxorhenium (MTO) complexed with pyridine was shown to be a highly effective catalyst for the regioselective monoepoxidation of conjugated di- and trienes using 30% H2O2 at or below room temperature. The resultant allylic epoxides, and the triols derived from them, are versatile synthetic intermediates as well as substructures present in many bioactive natural products. The site of epoxidation was dependent upon olefin substitution, olefin geometry (Z vs E), and the presence of electron-withdrawing substituents on adjacent carbons. For 1-acyl(silyl)oxypenta-2,4-dienes, epoxidation of the distal olefin was generally favored in contrast to the adjacent regioselectivity characteristic of Sharpless, peracid, and other directed epoxidations of hydroxylated dienes. PMID:25321319

  15. Lewis acid activation of carbodicarbene catalysts for Rh-catalyzed hydroarylation of dienes.

    PubMed

    Roberts, Courtney C; Matías, Desirée M; Goldfogel, Matthew J; Meek, Simon J

    2015-05-27

    The activation of carbodicarbene (CDC)-Rh(I) pincer complexes by secondary binding of metal salts is reported for the catalytic site-selective hydro-heteroarylation of dienes (up to 98% yield and >98:2 γ:α). Reactions are promoted by 5 mol % of a readily available tridentate (CDC)-Rh complex in the presence of an inexpensive lithium salt. The reaction is compatible with a variety of terminal and internal dienes and tolerant of ester, alkyl halide, and boronate ester functional groups. X-ray data and mechanistic experiments provide support for the role of the metal salts on catalyst activation and shed light on the reaction mechanism. The increased efficiency (120 to 22 °C) made available by catalytic amounts of metal salts to catalysts containing C(0) donors is a significant aspect of the disclosed studies. PMID:25961506

  16. Formal Asymmetric (4+1) Annulation Reaction between Sulfur Ylides and 1,3-Dienes.

    PubMed

    Rousseau, Olivier; Delaunay, Thierry; Dequirez, Geoffroy; Trieu-Van, Tran; Robeyns, Koen; Robiette, Raphaël

    2015-09-01

    A highly enantioselective synthesis of functionalized cyclopentanoids by a formal asymmetric (4+1) annulation strategy was developed. The methodology consists of a stereoselective cyclopropanation reaction between chiral sulfur ylides and 1,3-dienes followed by a, in situ, stereospecific MgI2 -catalyzed rearrangement of vinylcyclopropanes. This method is distinguished by a remarkable compatibility with functional groups and a high stereocontrol. PMID:26235566

  17. Asymmetric Conjugate Alkynylation of Cyclic α,β-Unsaturated Carbonyl Compounds with a Chiral Diene Rhodium Catalyst.

    PubMed

    Dou, Xiaowei; Huang, Yinhua; Hayashi, Tamio

    2016-01-18

    Asymmetric conjugate alkynylation of cyclic α,β-unsaturated carbonyl compounds (ketones, esters, and amides) was realized by use of diphenyl[(triisopropylsilyl)ethynyl]methanol as an alkynylating reagent in the presence of a rhodium catalyst coordinated with a new chiral diene ligand (Fc-bod; bod=bicyclo[2.2.2]octa-2,5-diene, Fc=ferrocenyl) to give high yields of the corresponding β-alkynyl-substituted carbonyl compounds with 95-98% ee. PMID:26636764

  18. Comment on: Discovery of the fossiliferous Cu Brei Formation (Lower Devonian) in the Kon Tum Block (South Viet Nam): Tong-Dzuy Thanh, Than Duc Duyen, Nguyen Huu Hung, Bui Phu My

    NASA Astrophysics Data System (ADS)

    Maluski, Henri

    2008-01-01

    The publication of Tong-Dzuy Thanh et al. calls for two remarks: The metamorphism in the "Kon Tum block" cannot be younger than Permian because the outcrop they describe is not metamorphic. Their very interesting discovery is a new piece of evidence for the exotic origin of the Dien Binh Series.

  19. Polymerization of 1,3-Conjugated Dienes with Rare-Earth Metal Precursors

    NASA Astrophysics Data System (ADS)

    Zhang, Zhichao; Cui, Dongmei; Wang, Baoli; Liu, Bo; Yang, Yi

    This chapter surveys the publications except patents related to cis-1,4-, trans-1,4-, 3,4-regio-, and stereoselective polymerizations of 1,3-conjugated dienes with rare-earth metal-based catalytic systems during the past decade from 1999 to 2009. The concerned catalyst systems are classified into the conventional Ziegler-Natta catalysts, the modified Ziegler-Natta catalysts, and the single-site cationic systems composed of lanthanocene and noncyclopentadienyl precursors, respectively. For the conventional Ziegler-Natta catalysts of the most promising industry applicable recipe, the multicomponents based on lanthanide carboxylate or phosphate or alkoxide precursors, research works concern mainly about optimizing the catalyst preparation and polymerization techniques. Special emphases are put on the factors that influence the catalyst homogeneority, catalytic activity and efficiency, as well as cis-1,4-selectivity. Meanwhile, tailor-made lanthanide aryloxide and amide complexes are designed and fully characterized to mimic the conventional Ziegler-Natta catalysts, anticipated to elucidate the key processes, alkylation and cationization, for generating the active species. Regarding to the single-site catalytic systems generally comprising well-defined complexes containing lanthanide-carbon bonds, investigations cover their versatile catalytic activity and efficiency, and the distinguished regio- and stereoselectivity for both polymerization of dienes and copolymerization of dienes with alkenes. The correlation between the sterics and electronics of ligands and the molecular structures of the complexes and their catalytic performances are highlighted. The isolation of the probable active species in these polymerization processes from the stoichiometric reactions of the precursors with activators will be presented.

  20. C-H Polyaddition of Dimethoxyarenes to Unconjugated Dienes by Rare Earth Catalysts.

    PubMed

    Shi, Xiaochao; Nishiura, Masayoshi; Hou, Zhaomin

    2016-05-18

    The C-H polyaddition of dimethoxyarenes such as 1,4-dimethoxybenzene and 4,4'-dimethoxybiphenyl to unconjugated dienes such as norbornadiene and 1,4-divinylbenzene has been achieved for the first time by using cationic half-sandwich rare earth alkyl catalysts. This protocol afforded novel polymer materials consisting of dimethoxyarene moieties and nonpolar hydrocarbon structure motifs (cyclic, linear, and aromatic) in perfectly alternating sequences that are otherwise difficult to make. The reaction proceeded via C═C double bond insertion into a C-H bond ortho to each of the two methoxy groups in a step-growth polymerization fashion. PMID:27149275

  1. Stereoselective Rh-Catalyzed Hydrogenative Desymmetrization of Achiral Substituted 1,4-Dienes.

    PubMed

    Fernández-Pérez, Héctor; Lao, Joan R; Vidal-Ferran, Anton

    2016-06-17

    Highly efficient catalytic stereoselective hydrogenative desymmetrization reactions mediated by rhodium complexes derived from enantiopure phosphine-phosphite (P-OP) ligands are described. The highest performing ligand, which contains a TADDOL-derived phosphite fragment [TADDOL = (2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanol)], presented excellent catalytic properties for the desymmetrization of a set of achiral 1,4-dienes, providing access to the selective formation of a variety of enantioenriched secondary and tertiary alcohols (six examples, up to 92% ee). PMID:27230728

  2. Food as a source of dioxin exposure in the residents of Bien Hoa City, Vietnam.

    PubMed

    Schecter, Arnold; Quynh, Hoang Trong; Pavuk, Marian; Päpke, Olaf; Malisch, Rainer; Constable, John D

    2003-08-01

    Recently, elevated dioxin levels, over 5 parts per trillion (ppt) 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), from Agent Orange was reported in 95% of 43 selected residents of Bien Hoa City, a city in southern Vietnam near a former air base used for Agent Orange-spraying missions. Agent Orange herbicide, contaminated with TCDD, was sprayed in Vietnam between 1962 and 1971 primarily for use as a defoliant. Typical blood TCCD levels are 2 ppt in Vietnamese, but levels are as high as 413 ppt in Bien Hoa City. Elevated TCDD was found in children born many years after Agent Orange spraying ended and in immigrants from non-Agent Orange-sprayed parts of Vietnam, which documented new exposures. Extremely elevated soil TCDD samples, over 1 million ppt, and elevated TCDD in sediment were found in some nearby areas such as Bien Hung Lake. The primary route of intake of almost all dioxins in humans is food. However, in our prior studies in Bien Hoa, food was unavailable for dioxin analysis so the route of intake was not confirmed. In the 1970s, while Agent Orange was still being sprayed, elevated human milk TCDD levels as high as 1850 were detected in milk from Vietnamese people living in Agent Orange-sprayed areas where consumption of fish was high. Furthermore, also in the 1970s, elevated TCDD levels (up to 810 ppt) were found in fish and shrimp from the same area as the milk donors. In the 1980s, we found elevated TCDD and also other organohalogen levels in human tissue, pork, fish, a turtle, and a snake in Southern Vietnam. For these reasons, we recently collected food from Bien Hoa and analyzed it for dioxins, polychlorinated biphenyls (PCBs), DDT and its metabolites, and other organochlorines. We found marked elevation of TCDD, the dioxin characteristic of Agent Orange, in some of the food products, including ducks with 276 ppt and 331 ppt wet weight, chickens from 0.031-15 ppt wet weight, fish from 0.063-65 ppt wet weight, and a toad with 56 ppt wet weight. Usual TCDD

  3. Unprecedented Intramolecular [4 + 2]-Cycloaddition between a 1,3-Diene and a Diazo Ester.

    PubMed

    Qiu, Huang; Srinivas, Harathi D; Zavalij, Peter Y; Doyle, Michael P

    2016-02-17

    Diazo compounds that are well-known to undergo [3 + 2]-cycloaddition provide the first examples of the previously unknown [4 + 2]-cycloaddition with dienes that occur thermally under mild conditions and in high yields. Reactions are initiated from reactants prepared from propargyl aryldiazoacetates that undergo gold(I)-catalyzed rearrangement to activated 1,3-dienyl aryldiazoacetates. These reactions proceed to mixtures of both [4 + 2]-cycloaddition and the 1,3-dienyl aryldiazoacetate after long reaction times. At short reaction times, however, both E- and Z-1,3-dienyl aryldiazoacetates are formed and, after isolation, thermal reactions with the E-isomers form the products from [4 + 2]-cycloaddition with ΔH(‡)298 = 15.6 kcal/mol and ΔS(‡)298 = -27.3 cal/(mol·°C). The Z-isomer is inert to [4 + 2]-cycloaddition under these conditions. The Hammett relationships from aryl-substituted diazo esters (ρ = +0.89) and aryl-substituted dienes (ρ = -1.65) are consistent with the dipolar nature of this transformation. PMID:26794409

  4. Ligand-based reactivity of a platinum bisdithiolene: double diene addition yields a new C2-chiral chelate ligand.

    PubMed

    Kerr, Mitchell J; Harrison, Daniel J; Lough, Alan J; Fekl, Ulrich

    2009-10-01

    The reaction of Pt(tfd)(2) [tfd = S(2)C(2)(CF(3))(2)] with excess 2,3-dimethyl-1,3-butadiene initially yields the expected 1:1 adduct, in which the diene has added across two sulfur atoms on separate tfd ligands. However, within 1 day at 50 degrees C, this kinetic product quantitatively converts into a thermodynamic product where two dienes have added to one tfd ligand via unprecedented addition across the dithiolene CS bonds. The new reaction is highly selective for the C(2)-symmetric diastereomer. A new chiral bisthioether chelate ligand has formed in the product, which has been characterized crystallographically. PMID:19634863

  5. Nitroso Diels-Alder (NDA) Reaction as an Efficient Tool for the Functionalization of Diene-Containing Natural Products

    PubMed Central

    Carosso, Serena; Miller, Marvin J.

    2014-01-01

    This review describes the use of nitroso Diels-Alder reactions for the functionalization of complex diene-containing natural products in order to generate libraries of compounds with potential biological activity. The application of this methodology to the structural modification of a series of natural products (thebaine, steroidal dienes, rapamycin, leucomycin, colchicine, isocolchicine and piperine) is discussed using relevant examples from the literature from 1973 onwards. The biological activity of the resulting compounds is also discussed. Additional comments are provided that evaluate the methodology as a useful tool in organic, bioorganic and medicinal chemistry. PMID:25119424

  6. Successive C-C Coupling of Dienes to Vicinally Dioxygenated Hydrocarbons: Ruthenium Catalyzed [4+2] Cycloaddition across the Diol, Hydroxycarbonyl or Dione Oxidation Levels

    PubMed Central

    Geary, Laina M.; Glasspoole, Ben W.; Kim, Mary M.; Krische, Michael J.

    2013-01-01

    The ruthenium(0) catalyst generated from Ru3(CO)12 and tricyclohexylphosphine or BIPHEP promotes successive C-C coupling of dienes to vicinally dioxygenated hydrocarbons across the diol, hydroxyketone and dione oxidation levels to form products of [4+2] cycloaddition. A mechanism involving diene-carbonyl oxidative coupling followed by intramolecular carbonyl addition from the resulting allylruthenium intermediate is postulated. PMID:23448269

  7. Strategic use of nickel(0)-catalyzed enyne-epoxide reductive coupling towards the synthesis of (−)-cyatha-3,12-diene

    PubMed Central

    Sparling, Brian A.; Simpson, Graham L.; Jamison, Timothy F.

    2009-01-01

    Various situations are explored in which the nickel(0)-catalyzed enyne-epoxide reductive coupling was utilized to access key intermediates towards the total synthesis of (−)-cyatha-3,12-diene (1). Enantioenriched 3,5-dien-1-ols with a variety of functionality were obtained in a straightforward manner from easily accessible 1,3-enynes and terminal epoxides. PMID:20161213

  8. Novel polymer composites from waste ethylene-propylene-diene-monomer rubber by supercritical CO2 foaming technology.

    PubMed

    Jeong, Keuk Min; Hong, Yeo Joo; Saha, Prosenjit; Park, Seong Ho; Kim, Jin Kuk

    2014-11-01

    In this study, a composite has been prepared by mixing waste rubber, such as ethylene-propylene-diene-monomer and low-density poly ethylene foaming, with supercritical carbon dioxide. In order to optimise the foaming process of the waste ethylene-propylene-diene-monomer-low-density poly ethylene composite, the variations of pressure and temperature on the foamed Microcell formation were studied. As indicated in scanning electron microscope photographs, the most uniform microcellular pattern was found at 200 bar and 100 °C using 30% by weight of waste ethylene-propylene-diene-monomer. Carbon dioxide could not be dissolved uniformly during foaming owing to extensive cross-linking of the waste ethylene-propylene-diene-monomer used for the composite. As a result the presence of un-uniform microcells after foaming were observed in the composite matrix to impart inferior mechanical properties of the composite. This problem was solved with uniform foaming by increasing the cross-link density of low-density poly ethylene using 1.5 parts per hundred dicumyl peroxide that enhances composite tensile and compressive strength up to 57% and 15%, respectively. The composite has the potential to be used as a foaming mat for artificial turf. PMID:25106537

  9. Mechanistic Aspects of the Palladium-Catalyzed Isomerization of Allenic Sulfones to 1-Arylsulfonyl 1,3-Dienes.

    PubMed

    Hampton, Carissa S; Harmata, Michael

    2016-06-01

    When an allenic sulfone is treated under palladium catalysis in the presence of a weak acid, isomerization to a 1-arylsulfonyl 1,3-diene occurs. Investigations of the mechanistic aspects of this isomerization were performed, leading to the mechanism proposed herein. Some further studies of reaction parameters are reported. PMID:27127922

  10. Total (1)H NMR assignment of 3β-acetoxypregna-5,16-dien-20-one.

    PubMed

    Becerra-Martinez, Elvia; Ramírez-Gualito, Karla E; Pérez-Hernández, Nury; Joseph-Nathan, Pedro

    2015-12-01

    This work describes the total and unambiguous assignment of the 750 MHz (1)H NMR spectrum of 3β-acetoxypregna-5,16-dien-20-one or 16-DPA (1), the well-known intermediate utilized in the synthesis of biological important commercial steroids. The task was accomplished by extracting the coupling constant values in the overlapped spectrum region by HSQC, and using these values in the (1)H iterative full spin analysis integrated in the PERCH NMR software. Comparison of the experimental vicinal coupling constants of 1 with the values calculated using Altona provides an excellent correlation. The same procedure, when applied to the published data of progesterone (2) and testosterone (3), afforded an acceptable correlation for 2 and a poor correlation for 3. In the last case, this suggested the reassignment of all four vicinal coupling constants for the methylene signals at the C-15 and C-16 positions, demonstrating the utility of this methodology. PMID:26476187

  11. Determination of double bond position in conjugated dienes by chemical ionization mass spectrometry with isobutane

    SciTech Connect

    Doolittle, R.E.; Tumlinson, J.H.; Proveaux, A.

    1985-07-01

    The chemical ionization (CI) mass spectra of a series of functionalized conjugated dienes, including aldehydes, alcohols, formates, acetates, and hydrocarbons were investigated to determine whether fragmentations occur that are characteristic of the position of the conjugated system within the hydrocarbon chain. CI with isobutane as ionizing gas produces structure-specific fragment ions with m/z ratios that can be used to locate the positions of the double bonds in most of the cases studied. When the conjugated system is proximal to the functional group or conjugated with the functional group, other fragmentation processes take precedence. These patterns of fragmentations constitute a very useful analytical tool for the location of conjugated double bonds in a variety of natural products. 34 references, 3 tables, 3 figures.

  12. 3α-Hy­droxy­tirucalla-8,24-dien-21-oic acid

    PubMed Central

    Yousuf, S.; Kamdem, R. S. T.; Ngadjui, B. T.; Wafo, P.; Fun, Hoong-Kun

    2011-01-01

    The title compound, C30H48O3, a triterpene isolated from the resin of canarium schweinfurthiiand, is an isomer of the previously reported triterpene 3α-hy­droxy­tirucalla-7,24-dien-21-oic acid [Mora et al. (2001 ▶). Acta Cryst. C57, 638–640], which crystallizes in the same trigonal space group. The title mol­ecule consists of four fused rings having chair, half-chair, half-chair and envelope conformations for rings A, B, C and D, respectively (steroid labelling). An intra­molecular C—H⋯O hydrogen bond generates an S(7) ring. In the crystal, mol­ecules are linked by O—H⋯O and C—H⋯O inter­actions, forming (001) sheets. PMID:21754206

  13. The diene isomerization energies dataset: A difficult test for double-hybrid density functionals?

    NASA Astrophysics Data System (ADS)

    Wykes, M.; Pérez-Jiménez, A. J.; Adamo, C.; Sancho-García, J. C.

    2015-06-01

    We have systematically analyzed the performance of some representative double-hybrid density functionals (including PBE0-DH, PBE-QIDH, PBE0-2, XYG3, XYGJ-OS, and xDH-PBE0) for a recently introduced database of diene isomerization energies. Double-hybrid models outperform their corresponding hybrid forms (for example, PBE0-DH, PBE0-2, and PBE-QIDH are more accurate than PBE0) and the XYG3, XYGJ-OS, and xDH-PBE0 functionals perform excellently, providing root mean square deviation values within "calibration accuracy." XYGJ-OS and xDH-PBE0 also rival the best performing post-Hartree-Fock methods at a substantially lower cost.

  14. Public health assessment of dioxin-contaminated fish at former US airbase, Bien Hoa, Vietnam.

    PubMed

    Durant, James T; Boivin, Thomas G; Pohl, Hana R; Sinks, Thomas H

    2015-01-01

    Ponds at the former US airbase at Ben Hoa, Vietnam are contaminated with Agent Orange. The ponds had been used for aquaculture, and in all likelihood, fish from those ponds have been sold to the public. We assessed human exposure to 2,3,7,8-tetrachloro-dibenzo-dioxin (2,3,7,8-TCDD) in fish samples from the ponds. For on-base tilapia, muscle concentrations 2,3,7,8-TCDD ranged from 1.4 to 32.7 pg/g. Fat concentrations ranged from 73.3 to 3990 pg/g. Estimated human exposure doses exceed international guidelines and exceed 2,3,7,8-TCDD's lowest adverse effect levels. The Bien Hoa fishponds are a completed human pathway for TCDD exposure. PMID:25087452

  15. Vertical distribution of dioxins in soil of Bien Hoa airbase, Vietnam.

    PubMed

    Huyen, Dang Thuong; Igarashi, Toshifumi; Shiraiwa, Takuya

    2015-01-01

    Bien Hoa airbase is a known dioxin-contaminated hotspot in Vietnam. The contamination occurred during the Vietnam War at the site where dioxins were transported, stored, sprayed, and spilled in the area. Dioxins, which are cancer inducing substances, may transfer from the soil to food crops and finally to human beings living around the area. Many surveys of dioxins in soil, water, organisms, and human have been carried out in this study area since 2002. In this paper vertical distribution of dioxins in undisturbed soil cores were examined. Twelve soil samples from three drilled cores were collected to analyze dioxin levels according to the standard Japanese analytical method. The results showed that the toxicity equivalency quantity (TEQ) in one soil sample at a depth of 2.6 m reached 3,300 pg-TEQ/g-dw. High TEQs were also observed in the clay layer. This anomaly of dioxin concentrations could be attributed to the affinity of dioxins for the clay layer. The isomer patterns in the soils were different from those in the soil of Hokkaido in that 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) was the most dominant in the soil sample. This indicates that the dioxins originate from a defoliant Agent Orange disposed at the site after the Vietnam War. PMID:26155439

  16. [Preparation of androsta-1,4-diene-3,17-dione from sterols using Mycobacterium neoaurum VKPM As-1656 strain].

    PubMed

    Molchanova, M A; Andriushina, V A; Savinova, T S; Stytsenko, T S; Rodina, N V; Voĭshvillo, N E

    2007-01-01

    A product of microbiological cleavage of the sterols side chain, androsta-1,4-diene-3,17-dione, is toxic for bacteria, in particular, actinobacteria of the genera Mycobacterium and Arthrobacter. Sterols were transformed into androsta-1,4-diene-3,17-dione by culturing the M. neoaurum VKPM An-1656 strain in a high yield, provided that a sorbent was used for elimination of contact between the bacterial cells and the product. Unlike the cholesterol side chain, the more branched chains of phytosterols were cleaved in the presence of M. neoaurum at a high rate only under turbulent stirring of the culture medium, which intensified the formation of hydrocarbonate ion from NaNI3 in situ. PMID:17682396

  17. Total Synthesis of the Galbulimima Alkaloids Himandravine and GB17 Using Biomimetic Diels–Alder Reactions of Double Diene Precursors

    PubMed Central

    Larson, Reed T.; Pemberton, Ryan P.; Franke, Jenna M.; Tantillo, Dean J.; Thomson, Regan J.

    2015-01-01

    The enantioselective total syntheses of himandravine and GB17 were completed through a common biomimetic strategy involving Diels–Alder reactions of unusual double diene containing linear precursors. The double diene precursors, containing or lacking a C12 substituent as required to produce GB17 or himandravine, respectively, were found to undergo Diels–Alder reactions to afford mixtures of regioisomeric cycloadducts that map onto the alternative carbocyclic frameworks of both himandravine and GB17. Computational investigations revealed that these Diels–Alder reactions proceed via transition state structures of similar energy that have a high degree of bispericyclic character and that the low levels of regioselectivity observed in the reactions are a consequence of competing orbital interaction and distortion energies. The combined experimental and computational results provide valuable insights into the biosynthesis of the Galbulimima alkaloids. PMID:26305231

  18. Synthesis of 1,3-Dienes via a Sequential Suzuki-Miyaura Coupling/Palladium-Mediated Allene Isomerization Sequence.

    PubMed

    Al-Jawaheri, Yassir; Kimber, Marc C

    2016-07-15

    We report a facile method for the synthesis of 1,3-dienes by a sequential process consisting of a palladium-catalyzed, base-free, Suzuki-Miyaura coupling/isomerization sequence. This sequence couples boronic acids with propargyl alcohols, generating the requisite allene in situ, followed by conversion of the unactivated allene to its 1,3-diene via a hydro-palladation/dehydro-palladation process. This process is general for a range of boronic acids, including boronic acids with electron-donating and -withdrawing groups, as well as heteroarylboronic acids. Key to this process is the boric acid byproduct of the base-free Suzuki-Miyauru coupling, which generates the required palladium-hydrido complex [H-Pd(II)-OB(OH)2] required for the isomerization. PMID:27355240

  19. Total Synthesis of the Galbulimima Alkaloids Himandravine and GB17 Using Biomimetic Diels-Alder Reactions of Double Diene Precursors.

    PubMed

    Larson, Reed T; Pemberton, Ryan P; Franke, Jenna M; Tantillo, Dean J; Thomson, Regan J

    2015-09-01

    The enantioselective total syntheses of himandravine and GB17 were completed through a common biomimetic strategy involving Diels-Alder reactions of unusual double diene containing linear precursors. The double diene precursors, containing or lacking a C12 substituent as required to produce GB17 or himandravine, respectively, were found to undergo Diels-Alder reactions to afford mixtures of regioisomeric cycloadducts that map onto the alternative carbocyclic frameworks of both himandravine and GB17. Computational investigations revealed that these Diels-Alder reactions proceed via transition state structures of similar energy that have a high degree of bispericyclic character and that the low levels of regioselectivity observed in the reactions are a consequence of competing orbital interaction and distortion energies. The combined experimental and computational results provide valuable insights into the biosynthesis of the Galbulimima alkaloids. PMID:26305231

  20. Ruthenium-catalyzed intramolecular metathesis of dienes and its application in the synthesis of bridged and spiro azabicycles

    NASA Astrophysics Data System (ADS)

    Kuznetsov, N. Yu; Bubnov, Yu N.

    2015-07-01

    The review presents a historical excursion into catalytic alkene metathesis, covering the problems of history of the discovery of this process, as well as investigations on the properties, structure and reactivity of the most popular ruthenium catalysts for metathesis, mechanism of their action and decomposition. The main part covers studies devoted to the syntheses of bridged azabicyclic and 1-azaspirocyclic compounds comprising the intramolecular metathesis of dienes as the key step. The formation of a bicyclic skeleton of a series of natural bridged (cocaine, ferruginine, calystegines, and anatoxin-a) and spiro (pinnaic acids, halichlorine, hystrionicotoxin, and cephalotaxine) azabicycles, as well as their analogues and compounds with larger rings is demonstrated. The methods for the synthesis of diene precursors and the conditions for final assembling of the bicyclic compounds are considered in detail. The generalization of the literature data allows one to efficiently carry out the mentioned process taking into account the most important features. The bibliography includes 129 references.

  1. The true identity of the triterpene component of Wyethia mollis, a lanosta-diene containing a tetrahydropyran E-ring.

    PubMed

    Smith, Cole T; Noll, Bruice; Waddell, Thomas G; Knight, Kyle S

    2013-03-01

    The crystal structure of a triterpene component of Wyethia mollis has been obtained and compared with the previously reported structure of the compound. The compound in the crystal structure, lanosta-8,24-dien-3-one, 16,23-epoxy-(161beta, 23R), (1), is different from the previously reported compound, but has identical NMR and mass spectrometric data. The revised structure contains a tetrahydropyran E ring, a structural moiety rare in steroid triterpenes. PMID:23678796

  2. Enantioselective Aminomethylamination of Conjugated Dienes with Aminals Enabled by Chiral Palladium Complex-Catalyzed C-N Bond Activation.

    PubMed

    Liu, Yang; Xie, Yinjun; Wang, Hongli; Huang, Hanmin

    2016-04-01

    A novel highly enantioselective aminomethylamination of conjugated dienes with aminals catalyzed by a chiral palladium complex ligated with BINOL-derived chiral diphosphinite has been successfully developed. This reaction proceeds via a Pd-catalyzed cascade C-N bond activation, aminomethylation, and asymmetric allylic amination reaction under mild reaction conditions, providing a unique and efficient strategy for the synthesis of enantiomerically pure allylic 1,3-diamines. PMID:26998813

  3. Ionizing radiation-induced destruction of benzene and dienes in aqueous media.

    PubMed

    Al-Sheikhly, Mohamad; Poster, Dianne L; An, Jung-Chul; Neta, Pedatsur; Silverman, Joseph; Huie, Robert E

    2006-05-01

    Pulse radiolysis with spectrophotometric and conductometric detection was utilized to study the formation and reactions of radicals from benzene and dienes in aqueous solutions. The benzene OH adduct, *C6H6OH, reacts with O2 (k = 3 x 10(8) L mol(-1) s(-1)) in a reversible reaction. The peroxyl radical, HOC6H6O2*, undergoes O2*- elimination, bimolecular decay, and reaction with benzene to initiate a chain reaction, depending on the dose rate, benzene concentration, and pH. The occurrence of the chain reaction is demonstrated in low-dose-rate gamma radiolysis experiments where the consumption of O2 was monitored. 1,4-Cyclohexadiene, 1,4-hexadiene, and 1,4-pentadiene form OH-adducts and undergo H-abstraction by O*- radicals. The OH-adducts react with O2 to form peroxyl radicals. These peroxyl radicals, however, do not undergo unimolecular O2*- elimination but rather decay by second-order processes, which lead to subsequent steps of O2*- elimination. PMID:16719115

  4. Response of ethylene propylene diene monomer rubber (EPDM) to simulant Hanford tank waste

    SciTech Connect

    NIGREY,PAUL J.

    2000-02-01

    This report presents the findings of the Chemical Compatibility Program developed to evaluate plastic packaging components that may be incorporated in packaging mixed-waste forms for transportation. Consistent with the methodology outlined in this report, the author performed the second phase of this experimental program to determine the effects of simulant Hanford tank mixed wastes on packaging seal materials. That effort involved the comprehensive testing of five plastic liner materials in an aqueous mixed-waste simulant. The testing protocol involved exposing the materials to {approximately}143, 286, 571, and 3,670 krad of gamma radiation and was followed by 7-, 14-, 28-, 180-day exposures to the waste simulant at 18, 50, and 60 C. Ethylene propylene diene monomer (EPDM) rubber samples subjected to the same protocol were then evaluated by measuring seven material properties: specific gravity, dimensional changes, mass changes, hardness, compression set, vapor transport rates, and tensile properties. The author has determined that EPDM rubber has excellent resistance to radiation, this simulant, and a combination of these factors. These results suggest that EPDM is an excellent seal material to withstand aqueous mixed wastes having similar composition to the one used in this study.

  5. Synthesis of brominated acenaphthylenes and their flame-retardant effects on ethylene-propylene-diene terpolymer

    SciTech Connect

    Morita, Y.; Hagiwara, M.

    1982-09-01

    Bromoacenaphthylenes and their condensates as flame-retardant reagents were synthesized by bromination of acenaphthylene using ZnCl/sub 2/ - CF/sub 3/COOH or FeCl/sub 3/ as catalysts and subsequent dehydrobromination. The chief components were identified as bromoacenaphthylene monomers when ZnCl/sub 2/ - CF/sub 3/COOH were used, and as their condensates (mostly trimers) in the case of FeCl/sub 3/. Their performance as flame-retardant reagents for ethylene-propylene-diene terpolymer (EPDM) was evaluated by measuring the oxygen index of finished compounds, and flammability by a vertical flammability test based on UL-94-VO. Both the monomers and the condensates demonstrated high flame-retardant effectiveness. The high efficiency was attributed to their excellent dispersity in the base polymer and their characteristic thermal decomposition behavior. In thermal gravimetric analysis (TGA), they decomposed in a very wide range of temperature (ca.200-560/sup 0/C), which covers the decomposition range of EPDM. This was attributed to the existence of bromines of different thermal stabilities in one molecule. This paper is a part of a series of studies to develop new flame retardants which can give high flame retardancy as well as stabilty against ionizing radiation to EPDM.

  6. Synthesis of Highly Functionalized Tri- and Tetrasubstituted Alkenes via Pd-Catalyzed 1,2-Hydrovinylation of Terminal 1,3-Dienes

    PubMed Central

    2016-01-01

    An efficient method for the construction of Csp2–Csp3 bond in a regio- and stereoselective fashion involving 1,3-terminal dienes, enol triflates/nonaflates, and sodium formate under Pd(0)-catalysis is described. The three component assembly allows trapping of a π-allyl intermediate, after the initial migratory insertion of the diene, by a hydride source that leads to structurally complex and synthetically challenging tri- and tetrasubstituted alkene building blocks. PMID:25555197

  7. Aza-Morita-Baylis-Hillman reactions and cyclizations of conjugated dienes activated by sulfone, ester, and keto groups.

    PubMed

    Sorbetti, Jovina M; Clary, Kristen N; Rankic, Danica A; Wulff, Jeremy E; Parvez, Masood; Back, Thomas G

    2007-04-27

    The aza-Morita-Baylis-Hillman reactions of aldimines 2 with several activated conjugated dienes were found to proceed smoothly in DMF in the presence of 3-hydroxyquinuclidine (HQD). Imines 2 reacted with 1-(p-toluenesulfonyl)-1,3-butadiene (3), methyl 2,4-pentadienoate (6), hexa-3,5-dien-2-one (7), and 1-phenylpenta-2,4-dien-1-one (8) to afford adducts 4, 13, 14, and 15, respectively. While products 4, 13, and 15 were formed as E,Z mixtures, adducts 14 were obtained as essentially pure E-isomers. Cyclization of the E-isomers of the products derived from the dienyl sulfone 3 and the dienoate ester 6 occurred via intramolecular conjugate addition under base-catalyzed conditions to afford functionalized piperidines 5 and 16, respectively. The aza-Morita-Baylis-Hillman reaction and subsequent cyclization of the imine 2a with 3 were also carried out as a one-pot reaction, while the reaction mixture was simultaneously irradiated at 300 nm to effect the photoisomerization of the unreactive Z-adduct of the corresponding 4 to the more reactive E-isomer. PMID:17381156

  8. In vivo anticancer, anti-inflammatory, and toxicity studies of mixed-ligand Cu(II) complexes of dien and its Schiff dibases with heterocyclic aldehydes and 2-amino-2-thiazoline. Crystal structure of [Cu(dien)(Br)(2a-2tzn)](Br)(H(2)O).

    PubMed

    Chaviara, A Th; Christidis, P C; Papageorgiou, A; Chrysogelou, E; Hadjipavlou-Litina, D J; Bolos, C A

    2005-11-01

    A new series of complexes of the type [Cu(dien)(2a-2tzn)Y(2)] and [Cu(dienXX)(2a-2tzn)Y(2)], where dien=diethylenetriamine and dienXX=Schiff dibase of diethylenetriamine formed with 2-furaldehyde (dienOO), 2-thiophenecarboxaldehyde (dienSS), or pyrrol-2-carboxaldehyde (dienNN); Y=Cl, Br or NO(3); and 2a-2tzn=2-amino-2-thiazoline, were synthesized and their structure established by C, H, N and Cu analysis; IR and electronic spectra; magnetic susceptibility; and molar conductivity. The isolated complexes are monomers, paramagnetic, and electrolytes of types 1:1 or 1:2. In both types of solid state complexes, [Cu(dien)(2a-2tzn)Y(2)] and [Cu(dienXX)(2a-2tzn)Y(2)], dien and its Schiff dibases are bonded to Cu(II) in a tridentate fashion through 3N atoms. The coordination sphere is completed by the endocyclic nitrogen of the thiazoline moiety and by two Cl, Br, or NO(3) groups with distorted octahedral geometry. The proposed structure of these compounds was supported by X-ray analysis of [Cu(dien)(Br)(2a-2tzn)](Br)(H(2)O). The coordination polyhedron around the copper atom can be described as a distorted square pyramid [Cu(dien)(Br)(2a-2tzn)](+). Its basal plane is occupied by the four nitrogen atoms of the dien and thiazoline ligands with Cu-N distances ranging between 1.996(6) and 2.032(3)A, and the axial position is occupied by one of the two bromine atoms (Br1) with a Cu1-Br1 bond distance of 2.782(1)A. The second bromine atom (Br2) is 4.694(2)A from the copper atom, which exists as a discrete anion and is responsible for the cationic nature of the complex. Results regarding toxicity, antitumor, and anti-inflammatory activities of the investigated compounds are promising and allow the selection of a lead compound for further biological studies. PMID:16144711

  9. Triarylphosphine Ligands with Hemilabile Alkoxy Groups. Ligands for Nickel(II)-Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vi-nylarenes, 1,3-Dienes, and Cycloisomerization of 1,6-Dienes

    PubMed Central

    Biswas, Souvagya; Zhang, Aibin; Raya, Balaram

    2014-01-01

    Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl-, 2-benzyloxymethylphenyl-diphenylphosphine (L5 and L6 respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at −55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, leading up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II)-complexes of 2-benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl-(L6) and 2-benzyloxyethyl-diphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II)-complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II)-complexes of N-heterocyclic carbene-ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions. PMID:25395919

  10. Triarylphosphine Ligands with Hemilabile Alkoxy Groups. Ligands for Nickel(II)-Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vi-nylarenes, 1,3-Dienes, and Cycloisomerization of 1,6-Dienes.

    PubMed

    Biswas, Souvagya; Zhang, Aibin; Raya, Balaram; RajanBabu, T V

    2014-07-01

    Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl-, 2-benzyloxymethylphenyl-diphenylphosphine (L5 and L6 respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at -55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, leading up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II)-complexes of 2-benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl-(L6) and 2-benzyloxyethyl-diphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II)-complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II)-complexes of N-heterocyclic carbene-ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions. PMID:25395919

  11. Tricyclo­[6.2.1.02,7]undeca-4,9-diene-3,6-dione

    PubMed Central

    Wang, Chongchen

    2008-01-01

    The title compound, C11H10O2, crystallizes with two independent mol­ecules in the asymmetric unit. In one mol­ecule, the dihedral angle between the mean planes of the C—C=C—C group of the diene unit and essentially planar cyclo­hexene ring is 51.07 (9)°, while in the other mol­ecule it is 54.49 (12)°. In the crystal structure, weak inter­molecular C—H⋯O inter­actions link the mol­ecules into columns along the b axis. PMID:21201200

  12. Soft Propargylic Deprotonation: Designed Ligand Enables Au-Catalyzed Isomerization of Alkynes to 1,3-Dienes

    PubMed Central

    2015-01-01

    By functionalizing the privileged biphenyl-2-ylphosphine with a basic amino group at the rarely explored 3′ position, the derived gold(I) complex possesses orthogonally positioned “push” and “pull” forces, which enable for the first time soft propargylic deprotonation and permit the bridging of a difference of >26 pKa units (in DMSO) between a propargylic hydrogen and a protonated tertiary aniline. The application of this design led to efficient isomerization of alkynes into versatile 1,3-dienes with synthetically useful scope under mild reaction conditions. PMID:24911158

  13. Synthesis and behavior of novel sulfonated water-soluble N-heterocyclic carbene (η(4)-diene) platinum(0) complexes.

    PubMed

    Ruiz-Varilla, Andrea M; Baquero, Edwin A; Silbestri, Gustavo F; Gonzalez-Arellano, Camino; de Jesús, Ernesto; Flores, Juan C

    2015-11-14

    A series of water-soluble (NHC)Pt(0)(dvtms) and (NHC)Pt(0)(AE) complexes containing different sulfonated NHC ligands (dvtms = divinyltetramethyldisiloxane and AE = diallyl ether) are reported. The dvtms compounds have been found to be quite robust and to display some conformational rigidity, whereas their AE counterparts are less stable and more flexible. The catalytic evaluation of these complexes in the hydrosilylation of alkynes in water revealed no benefits in favor of the complexes containing the more labile spectator diene (AE), and a fairly regular catalytic behavior for all complexes that restricts the location of the sulfonate group to the proximity of the metal site. PMID:26346995

  14. Bicyclo[3.2.1]octa-3,6-dien-2-yl cation: a bishomoantiaromate.

    PubMed

    Volz, Heinrich; Shin, Jung-Hyu

    2006-03-17

    Antiaromatic compounds with a closed loop of 4n p-electrons are relatively unstable and often difficult to study. We report in this article the synthesis of alcohols 2-(4'-fluorophenyl)bicyclo[3.2.1]octan-2-ol 11, 2-(4'-fluorophenyl)bicyclo[3.2.1]oct-3-en-2-ol 12, and 2-(4'-fluorophenyl)bicyclo[3.2.1]octa-3,6-dien-2-ol 13 and their transformations into corresponding carbocations 14-16, respectively, in a superacidic medium (FSO3H/SO2ClF) at -120 degrees C. Cations 14-16 are characterized by NMR analysis (1H, 13C, 19F), and 15 and 16 are further characterized by quenching in NaOCH3/H3COH at -120 degrees C. The relative stabilities of 14-16 are determined experimentally by 19F NMR spectroscopy. Cation 16 is found to be experimentally less stable than cation 15 by 3.7 kcal/mol. DFT calculations (structure and energy: B3LYP/6-31G(d); NMR: B3LYP/6-311+G(2d,p)) are performed for alcohols 11-13 and bicyclo[3.2.1]octyl cations 6, 7, 9, 14-16, 26, 28, and 30. In the case of 11-16, data from DFT calculations is in good agreement with experimental data. Because 6,7-dimethylenebicyclo[3.2.1]oct-3-en-2-yl cation 26 is more stable than cation 7 by 1.69 kcal/mol, the inductive effect of sp(2)-hybridized carbon atoms C6 and C7 in carbocations 6 and 16 cannot be the reason for the destabilization of 6 relative to 7 and 16 relative to 15. Destabilization of 6 relative to 7 and 16 relative to 15 and the calculated NICS of 6 (+4.17 ppm) and 16(+3.3 ppm) document that 6 and 16 are bishomoantiaromates. PMID:16526766

  15. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln==Sm, Eu, Gd) and [Ln(dien)2(1κ2-AsS4)] (Ln==Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-01

    Solvothermal reactions of Ln2O3, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien)2(μ-1κ,2κ2-AsS4)]n [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien)2(1κ2-AsS4)] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln2O3 oxides were converted to [Ln(dien)2]3+ complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS4 unit. In 1-3, the AsS4 units interconnect the [Ln(dien)2]3+ cations via Ln-S bonds as tridentate μ-1κ,2κ2-AsS4 bridging ligands, resulting in the neutral coordination polymers [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln1). In 4-6, the AsS4 units coordinate with the Ln3+ ion of [Ln(dien)2]3+ as 1κ2-AsS4 chelating ligands to form neutral coordination compounds [Ln(dien)2(1κ2-AsS4)] (Ln2). The Ln3+ ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln3+ ions. Optical absorption spectra showed that 1-6 have potential use as semiconductors with the band gaps in the range 2.18-3.21 eV.

  16. Ambient temperature ligation of diene functional polymer and peptide strands onto cellulose via photochemical and thermal protocols.

    PubMed

    Tischer, Thomas; Claus, Tanja K; Oehlenschlaeger, Kim K; Trouillet, Vanessa; Bruns, Michael; Welle, Alexander; Linkert, Katharina; Goldmann, Anja S; Börner, Hans G; Barner-Kowollik, Christopher

    2014-06-01

    In the present contribution, two novel ambient temperature avenues are introduced to functionalize solid cellulose substrates in a modular fashion with synthetic polymer strands (poly(trifluoro ethyl methacrylate), PTFEMA, Mn = 4400 g mol(-1) , Đ = 1.18) and an Arg-Gly-Asp (RGD) containing peptide sequence. Both protocols rely on a hetero Diels-Alder reaction between an activated thiocarbonyl functionality and a diene species. In the first-thermally activated-protocol, the cellulose features surface-expressed thiocarbonylthio compounds, which readily react with diene terminal macromolecules at ambient temperature. In the second protocol, the reactive ene species are photochemically generated based on a phenacyl sulfide-decorated cellulose surface, which upon irradiation expresses highly reactive thioaldehyde species. The generated functional hybrid surfaces are characterized in-depth via ToF-SIMS and XPS analysis, revealing the successful covalent attachment of the grafted materials, including the spatially resolved patterning of both synthetic polymers and peptide strands using the photochemical protocol. The study thus provides a versatile platform technology for solid cellulose substrate modification via efficient thermal and photochemical ligation strategies. PMID:24706565

  17. A gold-catalyzed unique cycloisomerization of 1,5-enynes: efficient formation of 1-carboxycyclohexa-1,4-dienes and carboxyarenes.

    PubMed

    Wang, Shaozhong; Zhang, Liming

    2006-11-01

    A novel Au-catalyzed migratory cycloisomerization strategy is advanced. Implementation of this strategy led to the development of a unique Au-catalyzed 1,5-enyne cycloisomerizatioin involving carboxy migration and Au-mediated C-C single bond formation. 1-Carboxycyclohexa-1,4-dienes and carboxyarenes can be prepared with good efficiency and with flexible substitution patterns. PMID:17076498

  18. Development of palladium-carbene catalysts for telomerization and dimerization of 1,3-dienes: from basic research to industrial applications.

    PubMed

    Clement, Nicolas D; Routaboul, Lucie; Grotevendt, Anne; Jackstell, Ralf; Beller, Matthias

    2008-01-01

    The following account summarises recent developments in the area of palladium-catalysed telomerisation and dimerisation reactions of 1,3-dienes. The most active types of catalyst, palladium-carbene complexes, were tested in pilot plant and proved to be industrially viable. PMID:18680130

  19. Computational Examination of (4 + 3) versus (3 + 2) Cycloaddition in the Interception of Nazarov Reactions of Allenyl Vinyl Ketones by Dienes.

    PubMed

    Li, Zhe; Boyd, Russell J; Burnell, D Jean

    2015-12-18

    A computational examination of the tandem Nazarov/cycloaddition process involving an allenyl vinyl ketone with a diene has been carried out using the ωB97X-D/6-311++G(d,p)//ωB97X-D/6-31+G(d,p) method with solvation modeled by SMD-PCM. The barrier for the initial Lewis acid mediated Nazarov reaction, which provided the intermediate cyclic oxylallyl cation, was higher than that for any subsequent cycloaddition. The barrier for the first step of a subsequent stepwise reaction did not vary much with the diene, and the lowest barrier was with the diene in its s-trans conformation. Stepwise formation of a (4 + 3) cycloaddition product was not energetically feasible, but (3 + 2) cycloaddition products could have been produced through low energy pathways. The barrier for a concerted (4 + 3) cycloaddition did depend upon the diene, which was always in an s-cis geometry. The barriers for the compact and the extended geometries for the transition states of (4 + 3) cycloadditions were not much different. PMID:26595587

  20. Cu(I)-catalyzed diamination of conjugated dienes. Complementary regioselectivity from two distinct mechanistic pathways involving Cu(II) and Cu(III) species.

    PubMed

    Zhao, Baoguo; Peng, Xingao; Zhu, Yingguang; Ramirez, Thomas A; Cornwall, Richard G; Shi, Yian

    2011-12-28

    Conjugated dienes can be diaminated at the internal and/or terminal double bonds using Cu(I) as catalyst and N,N-di-t-butyldiaziridinone (1) as nitrogen source. The regioselectivity is highly dependent upon the choice of Cu(I) catalyst and the substituents on diene substrates. The diamination likely proceeds via two mechanistically distinct pathways. The N-N bond of N,N-di-t-butyldiaziridinone (1) is first homolytically cleaved by the Cu(I) catalyst to form four-membered Cu(III) species A and Cu(II) radical species B, which are in rapid equilibrium. The internal diamination likely proceeds in a concerted manner via Cu(III) species A, and the terminal diamination likely involves Cu(II) radical species B. Kinetic studies have shown that the diamination is first-order in N,N-di-t-butyldiaziridinone (1), zero-order in olefin, and first-order in total Cu(I) catalyst, and the cleavage of the N-N bond of 1 by the Cu(I) catalyst is the rate-determining step. The internal diamination is favored by use of CuBr without ligand and electron-rich dienes. The terminal diamination is favored when using CuCl-L and dienes with radical-stabilizing groups. PMID:22081888

  1. Cu(I)-Catalyzed Diamination of Conjugated Dienes. Complementary Regioselectivity from Two Distinct Mechanistic Pathways Involving Cu(II) and Cu(III) Species

    PubMed Central

    Zhao, Baoguo; Peng, Xingao; Zhu, Yingguang; Ramirez, Thomas A.; Cornwall, Richard G.

    2011-01-01

    Conjugated dienes can be diaminated at the internal and/or terminal double bonds using Cu(I) as catalyst and N,N-di-t-butyldiaziridinone (1) as nitrogen source. The regioselectivity is highly dependent upon the choice of Cu(I) catalyst and the substituents on diene substrates. The diamination likely proceeds via two mechanistically distinct pathways. The N-N bond of N,N-di-t-butyldiaziridinone (1) is first homolytically cleaved by the Cu(I) catalyst to form four-membered Cu(III) species A and Cu(II) radical species B, which are in rapid equilibrium. The internal diamination likely proceeds in a concerted manner via Cu(III) species A and the terminal diamination likely involves Cu(II) radical species B. Kinetic studies have shown that the diamination is first-order in N,N-di-t-butyldiaziridinone (1), zero-order in olefin, first-order in total Cu(I) catalyst, and the cleavage of the N-N bond of 1 by the Cu(I) catalyst is the rate-determining step. The internal diamination is favored by use of CuBr without ligand and electron-rich dienes. The terminal diamination is favored when using CuCl-L and dienes with radical-stabilizing groups. PMID:22081888

  2. Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

    NASA Astrophysics Data System (ADS)

    Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

    2011-01-01

    Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

  3. Synthesis, crystal growth and characterization of 1,5-diphenylpenta-1,4-dien-3-one: An organic crystal

    NASA Astrophysics Data System (ADS)

    Vanchinathan, K.; Bhagavannarayana, G.; Muthu, K.; Meenakshisundaram, S. P.

    2011-11-01

    1,5-Diphenylpenta-1,4-dien-3-one ( dibenzalacetone, DBA) was synthesized by a base-catalyzed aldol condensation reaction between benzaldehyde and acetone. High quality single crystals have been grown by the slow evaporation of ethanol solution and the crystal belongs to monoclinic system with centrosymmetric space group C 2/c. The DBA crystals are transparent in the entire visible region and have a lower optical cutoff at ∼440 nm. It is stable up to 119 °C and has a good chemical stability. The high resolution X-ray diffraction curve (DC) indicates that the specimen is free from structural grain boundaries. Molecular packing leads to a centrosymmetric arrangement resulting in zero second harmonic generation (SHG; χ(2)=0) efficiency.

  4. Synthesis, crystal structure and properties of [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} with mixed-valent Ge centers

    SciTech Connect

    Yue, Cheng-Yang; Yuan, Zhuang-Dong; Zhang, Lu-Ge; Wang, Ya-Bai; Liu, Guo-Dong; Gong, Liao-Kuo; Lei, Xiao-Wu

    2013-10-15

    One new manganese thiogermanate, [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} (dien=diethylenetriamine), was prepared under mild solvothermal conditions and structurally and spectroscopically characterized. The title compound crystallizes in the orthorhombic system, chiral space group P2{sub 1}2{sub 1}2{sub 1} (no. 19) with a=9.113(4) Å, b=12.475(5) Å, c=17.077(7) Å, V=1941.5(15) Å{sup 3} and Z=4. Its structure features a three-dimensional (3D) network composed of a one-dimensional (1D) [Ge{sub 2}S{sub 4}]{sup 2−} anionic chain and a [(dien){sub 2}Mn]{sup 2+} complex interconnected via various hydrogen bonds. The most interesting structural feature of the compound is the presence of two different oxidation states of germanium centers in the 1D [Ge{sub 2}S{sub 4}]{sup 2−} chain, which is also supported by the result of X-ray photoelectron spectroscopy measurement. The optical property of the title compound has also been studied by UV–vis spectra. - Graphical abstract: One new thiogermanate, [(dien){sub 2}Mn]Ge{sub 2}S{sub 4}, contains a one-dimensional [Ge{sub 2}S{sub 4}]{sup 2−} anionic chain with two different oxidation states of germanium centers. Display Omitted - Highlights: • One new manganese thiogermanate [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} was prepared. • The compound features 1D [Ge{sub 2}S{sub 4}]{sup 2−} chain composed of [Ge{sup II}S{sub 4}] and [Ge{sup IV}S{sub 4}] tetrahedra. • The first example of inorganic–organic hybrid thiogermanates with mixed valent Ge centers.

  5. Transport and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans at the Bien Hoa Agent Orange hotspot in Vietnam.

    PubMed

    Van Thuong, Nguyen; Hung, Nguyen Xuan; Mo, Nguyen Thi; Thang, Nguyen Manh; Huy, Pham Quang; Van Binh, Hoang; Nam, Vu Duc; Van Thuy, Nguyen; Son, Le Ke; Minh, Nguyen Hung

    2015-10-01

    The Bien Hoa airbase (south of Vietnam) is known as one of the Agent Orange hotspots which have been seriously contaminated by Agent Orange/dioxin during the Vietnam War. Hundreds of samples including soil, sediment and fish were collected at the Bien Hoa Agent Orange hotspot for assessment of the environmental contamination caused by dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The toxicity equivalency quotient (TEQ) concentration of PCDD/Fs in soil and sediment varied from 7.6 to 962,000 and 17 to 4860 pg/g dry wt, respectively, implying very high contamination of PCDD/Fs in several areas. PCDD/F levels in fish ranged between 1.8 and 288 pg/g TEQ wet wt and was generally higher than advisory guidelines for food consumption. 2,3,7,8-Tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) contributed 66-99 % of TEQ for most of the samples, suggesting 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) from Agent Orange as the major source of the contamination. The vertical transport of PCDD/Fs was observed in soil column with high TEQ levels above 1000 pg/g dry wt (Vietnamese limit for necessary remediation activities- TCVN 8183:2009 (2009)) even at a depth of 1.8 m. The vertical transport of PCDD/Fs has probably mainly taken place during the "Ranch Hand" defoliant spray activities due to the leaks and spills of phenoxy herbicides and solvents. The congener patterns suggest that transports of PCDD/Fs by weathering processes have led to their redistribution in the low-land areas. Also, an estimate for the total volume of contaminated soil requiring remediation to meet Vietnamese regulatory limits is provided. PMID:25510612

  6. Direct, redox-neutral prenylation and geranylation of secondary carbinol C-H bonds: C4-regioselectivity in ruthenium-catalyzed C-C couplings of dienes to α-hydroxy esters.

    PubMed

    Leung, Joyce C; Geary, Laina M; Chen, Te-Yu; Zbieg, Jason R; Krische, Michael J

    2012-09-26

    The ruthenium catalyst generated in situ from Ru(3)(CO)(12) and tricyclohexylphosphine, PCy(3), promotes the redox-neutral C-C coupling of aryl-substituted α-hydroxy esters to isoprene and myrcene at the diene C4-position, resulting in direct carbinol C-H prenylation and geranylation, respectively. This process enables direct conversion of secondary to tertiary alcohols in the absence of stoichiometric byproducts or premetalated reagents, and is the first example of C4-regioselectivity in catalytic C-C couplings of 2-substituted dienes to carbonyl partners. Mechanistic studies corroborate a catalytic cycle involving diene-carbonyl oxidative coupling. PMID:22985393

  7. A new C12 alcohol identified as a sex pheromone and a trail-following pheromone in termites: the diene (Z,Z)-dodeca-3,6-dien-1-ol.

    PubMed

    Robert, Alain; Peppuy, Alexis; Sémon, Etienne; Boyer, François D; Lacey, Michael J; Bordereau, Christian

    2004-01-01

    The diunsaturated C12 alcohol (Z,Z)-dodeca-3,6-dien-1-ol (dodecadienol) has been characterized by GC-MS and FTIR as a novel releaser pheromone in termites. This alcohol identified in Ancistrotermes pakistanicus (Termitidae, Macrotermitinae) possesses a double pheromonal function which again illustrates the chemical parsimony of termites compared with other social insects. In workers, dodecadienol elicits trail-following at a very low concentration (activity threshold at 0.1 pg/cm of trail); in male alates it induces trail-following at a low concentration (1-10 pg/cm) and sexual attraction at a higher concentration (about 1 ng). Traces of the monounsaturated C12 alcohol (Z)-dodec-3-en-1-ol (dodecenol), known as a trail pheromone of several Macrotermitinae, were also found in the sternal gland extracts of A. pakistanicus, although only dodecadienol was present at the surface of the sternal gland. Workers of A. pakistanicus are not sensitive to dodecenol, but they are as sensitive to dodecatrienol as to dodecadienol. However, in the study area (Vietnam), A. pakistanicus is living in sympatry only with those Macrotermitinae using dodecenol as a trail pheromone, the foraging populations therefore being well isolated through their respective trail pheromones. The presence of three types of unsaturated C12 alcohols as releaser pheromones in the only Macrotermitinae subfamily is discussed, and a possible biosynthetic pathway from linoleic acid is proposed for dodecadienol. PMID:14740102

  8. Base-catalyzed intramolecular hydroamination of cyclohexa-2,5-dienes: insights into the mechanism through DFT calculations and application to the total synthesis of epi-elwesine.

    PubMed

    Rousseau, Géraldine; Lebeuf, Raphaël; Schenk, Kurt; Castet, Frédéric; Robert, Frédéric; Landais, Yannick

    2014-11-01

    The base-catalyzed intramolecular hydroamination of 1-ethylaminocyclohexa-2,5-dienes is described. The transformation proceeds through isomerization of the cyclohexa-1,4-dienyl fragment into the corresponding conjugated 1,3-diene prior to the hydroamination step. Attaching a chiral glycinol ether auxiliary on the amino group allows the protonation to occur with complete diastereocontrol. The resulting lithium amide then adds onto the 1,3-dienyl moiety, affording the desired fused pyrrolidine ring along with the corresponding lithium allylic anion. Protonation of the latter then proceeds with high regiocontrol to favor the resulting allylic amines. In contrast, when the reaction was performed on primary amines, fused pyrrolidines bearing a homoallylic amino group were obtained. The stereochemical course of the process and determination of the reaction pathways were established based on calculations performed at the DFT level. Finally, application of the methodology to the enantioselective synthesis of (+)-epi-elwesine, a crinane alkaloid, is described. PMID:25223607

  9. Oxidative Cyclization of 1,5-Dienes with Hydrogen Peroxide Catalyzed by an Osmium(III) Complex: Synthesis of cis-Tetrahydrofurans.

    PubMed

    Sugimoto, Hideki; Kanetake, Takayuki; Maeda, Kazuki; Itoh, Shinobu

    2016-03-18

    Stereoselective oxidative cyclization of 1,5-dienes with hydrogen peroxide catalyzed by [Os(III)(OH)(H2O)(L-N4Me2)](PF6)2 (1: L-N4Me2 = N,N'-dimethyl-2,11-diaza-[3,3](2,6)pyridinophane) is explored. 1,5-Dienes involving geraniol derivatives are converted to the corresponding tetrahydrofurans in modest to high yields. The products exclusively have the cis-conformation with respect to the substituents at the 2- and 5-positions of the tetrahydrofuran ring. The products also have a syn-conformation with respect to the furan oxygen atom and the hydroxyl groups. Mechanistic studies including a direct reaction of the oxo-hydroxo-osmium(V) complex, 2, with a dihydroxylated geraniol derivative are performed. PMID:26950609

  10. A simple and efficient approach to the synthesis of endo and exo bicyclo[6.1.0]nona-3,5-diene-9-carboxaldehyde.

    PubMed

    Ghandi, Mehdi; Mashayekhi, Gholamreza

    2007-01-01

    Monobromination of 1,5-cyclooctadiene, followed by cyclopropanation with ethyl diazoacetate, led to the formation of endo and exo ethyl 4,5-dibromobicyclo[6.1.0]nonane-9-carboxylates 3a and 3b. Bis-dehydrobromination of 3a and 3b using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) afforded the endo and exo ethyl bicyclo[6.1.0]nona-3,5-diene-9-carboxylates 4a and 4b. Reduction of these compounds to the corresponding alcohols 5a and 5b and subsequent oxidation with pyridinium chlorochromate (PCC) resulted in the formation of the target compounds endo and exo bicyclo[6.1.0]nona-3,5-diene-9-carboxaldehydes 6a and 6b. PMID:17978767

  11. Highly Chemo- and Regioselective Construction of Spirocarbocycles by a Pd(0)-Catalyzed Dearomatization of Phenol-Based Biaryls with 1,3-Dienes.

    PubMed

    Luo, Lei; Zheng, Huayu; Liu, Jingjing; Wang, Hui; Wang, Yaoyu; Luan, Xinjun

    2016-05-01

    A novel Pd(0)-catalyzed intermolecular carbocyclization of phenol-derived biaryls with 1,3-dienes has been implemented through a sequence of oxidative addition to the C-I bond, regioselective olefin insertion, and allylative dearomatization. This method provides a broad range of attractive spirocyclic compounds bearing two contiguous tertiary/quaternary carbon centers in good yields with excellent chemoselectivity and regioselectivity. Moreover, preliminary results indicate that asymmetric control of this process is feasible with chiral ligands. PMID:27120015

  12. Environmental Health Risk Assessment of Dioxin Exposure through Foods in a Dioxin Hot Spot—Bien Hoa City, Vietnam

    PubMed Central

    Tuyet-Hanh, Tran Thi; Vu-Anh, Le; Ngoc-Bich, Nguyen; Tenkate, Thomas

    2010-01-01

    This study used the Australian Environmental Health Risk Assessment Framework to assess the human health risk of dioxin exposure through foods for local residents in two wards of Bien Hoa City, Vietnam. These wards are known hot-spots for dioxin and a range of stakeholders from central government to local levels were involved in this process. Publications on dioxin characteristics and toxicity were reviewed and dioxin concentrations in local soil, mud, foods, milk and blood samples were used as data for this risk assessment. A food frequency survey of 400 randomly selected households in these wards was conducted to provide data for exposure assessment. Results showed that local residents who had consumed locally cultivated foods, especially fresh water fish and bottom-feeding fish, free-ranging chicken, duck, and beef were at a very high risk, with their daily dioxin intake far exceeding the tolerable daily intake recommended by the WHO. Based on the results of this assessment, a multifaceted risk management program was developed and has been recognized as the first public health program ever to have been implemented in Vietnam to reduce the risks of dioxin exposure at dioxin hot-spots. PMID:20623031

  13. Diene Valepotriates from Valeriana glechomifolia Prevent Lipopolysaccharide-Induced Sickness and Depressive-Like Behavior in Mice.

    PubMed

    Müller, Liz G; Borsoi, Milene; Stolz, Eveline D; Herzfeldt, Vivian; Viana, Alice F; Ravazzolo, Ana Paula; Rates, Stela Maris K

    2015-01-01

    Valeriana glechomifolia, a native species from southern Brazil, presents antidepressant-like activity and diene valepotriates (VAL) contribute to the pharmacological properties of the genus. It is known that depression can develop on an inflammation background in vulnerable patients and antidepressants present anti-inflammatory properties. We investigated the effects of VAL (10 mg/kg, p.o.) on sickness and depressive-like behaviors as well as proinflammatory cytokines (IL-1β and TNF-α) and BDNF expression in the cortex of mice exposed to a 5 min swimming session (as a stressful stimulus) 30 min before the E. coli LPS injection (600 µg/kg, i.p.). The forced swim + LPS induced sickness and depressive-like behaviors, increased the cortical expression of IL-1β and TNF-α, and decreased BDNF expression. VAL was orally administered to mice 1 h before (pretreatment) or 5 h after (posttreatment) E. coli LPS injection. The pretreatment with VAL restored the behavioral alterations and the expression of cortical proinflammatory cytokines in LPS-injected animals but had no effects on BDNF expression, while the posttreatment rescued only behavioral alterations. Our results demonstrate for the first time the positive effects of VAL in an experimental model of depression associated with inflammation, providing new data on the range of action of these molecules. PMID:26170871

  14. Radiation processed polychloroprene-co-ethylene-propene diene terpolymer blends: Effect of radiation vulcanization on solvent transport kinetics

    NASA Astrophysics Data System (ADS)

    Dubey, K. A.; Bhardwaj, Y. K.; Chaudhari, C. V.; Kumar, Virendra; Goel, N. K.; Sabharwal, S.

    2009-03-01

    Blends of polychloroprene rubber (PCR) and ethylene propylene diene terpolymer rubber (EPDM) of different compositions were made and exposed to different gamma radiation doses. The radiation sensitivity and radiation vulcanization efficiency of blends was estimated by gel-content analysis, Charlesby-Pinner parameter determination and crosslinking density measurements. Gamma radiation induced crosslinking was most efficient for EPDM ( p0/ q0 ˜ 0.08), whereas it was the lowest for blends containing 40% PCR ( p0/ q0 ˜ 0.34). The vulcanized blends were characterized for solvent diffusion characteristics by following the swelling dynamics. Blends with higher PCR content showed anomalous swelling. The sorption and permeability of the solvent were not strictly in accordance with each other and the extent of variation in two parameters was found to be a function of blend composition. The Δ G values for solvent diffusion were in the range -2.97 to -9.58 kJ/mol and indicated thermodynamically favorable sorption for all blends. These results were corroborated by dynamic swelling, experimental as well as simulated profiles and have been explained on the basis of correlation between crosslinking density, diffusion kinetics, thermodynamic parameters and polymer-polymer interaction parameter.

  15. Diene Valepotriates from Valeriana glechomifolia Prevent Lipopolysaccharide-Induced Sickness and Depressive-Like Behavior in Mice

    PubMed Central

    Müller, Liz G.; Borsoi, Milene; Stolz, Eveline D.; Herzfeldt, Vivian; Viana, Alice F.; Ravazzolo, Ana Paula; Rates, Stela Maris K.

    2015-01-01

    Valeriana glechomifolia, a native species from southern Brazil, presents antidepressant-like activity and diene valepotriates (VAL) contribute to the pharmacological properties of the genus. It is known that depression can develop on an inflammation background in vulnerable patients and antidepressants present anti-inflammatory properties. We investigated the effects of VAL (10 mg/kg, p.o.) on sickness and depressive-like behaviors as well as proinflammatory cytokines (IL-1β and TNF-α) and BDNF expression in the cortex of mice exposed to a 5 min swimming session (as a stressful stimulus) 30 min before the E. coli LPS injection (600 µg/kg, i.p.). The forced swim + LPS induced sickness and depressive-like behaviors, increased the cortical expression of IL-1β and TNF-α, and decreased BDNF expression. VAL was orally administered to mice 1 h before (pretreatment) or 5 h after (posttreatment) E. coli LPS injection. The pretreatment with VAL restored the behavioral alterations and the expression of cortical proinflammatory cytokines in LPS-injected animals but had no effects on BDNF expression, while the posttreatment rescued only behavioral alterations. Our results demonstrate for the first time the positive effects of VAL in an experimental model of depression associated with inflammation, providing new data on the range of action of these molecules. PMID:26170871

  16. Metal Catalysis in Thiolation and Selenation Reactions of Alkynes Leading to Chalcogen‐Substituted Alkenes and Dienes

    PubMed Central

    2015-01-01

    Abstract This review covers recent achievements in metal‐catalyzed Z−H and Z−Z (Z=S, Se) bond addition to the triple bonds of alkynes—a convenient and atom‐efficient way to carbon‐element bond formation. Various catalytic systems (both homogeneous and heterogeneous) developed to date to obtain mono‐ and bis‐chalcogen‐substituted alkenes or dienes, as well as carbonyl compounds or heterocycles, starting from simple and available alkynes and chalcogenols or dichalcogenides are described. The right choice of metal and ligands allows us to perform these transformations with high selectivities under mild reaction conditions, thus tolerating unprotected functional groups in substrates and broadening ways of further modification of the products. The main aim of the review is to show the potential of the catalytic methods developed in synthetic organic chemistry. Thus, emphasis is made on the scope of reactions, types of products that can be selectively formed, convenience, and scalability of the catalytic procedures. A brief mechanistic description is also given to introduce new readers to the topic. PMID:27308193

  17. Structure Revision of (22E)-Ergosta-7,22-diene-3β,5α,6β,9α,14α- pentol from the Spores of the Medicinal Mushroom Ganoderma lucidum.

    PubMed

    Yaoita, Yasunori; Machida, Koichi

    2016-02-01

    Careful reexamination of the published ¹H and ¹³C NMR spectral data of (22E)-ergosta-7,22-diene-3β,5α,6β,9α,14α-pentol (1), isolated from the spores of the medicinal mushroom Ganoderma lucidum, indicates that, in reality, the compound is (22E)-ergosta-7,22-diene-3β,5α,6β,9α,14β-pentol (5). PMID:27032196

  18. Theoretical investigation of the stereochemistry of the polymerization of. cap alpha. -olefins and dienes with the participation of Ziegler-Natta catalysts

    SciTech Connect

    Minsker, K.S.; Karpasas, M.M.

    1986-09-01

    The processes involved in the formation of the active polymerization sites in heterogeneous Ziegler-Natta catalysts have been investigated with consideration of the real structure of the components by the atom-atom potential method, the Monte-Carlo method, a modified diatomics-in-molecules method, and the CNDO/2 method with the aid of the available experimental facts. It has been shown that three types of bimetallic active sites (AS), which differ with respect to the spatial configuration of the coordination sphere, viz., AS-1, AS-2, and AS-3, form, depending on the electronic structure of the homogeneous component R /SUB n/ M, the ionic radius of M (M is a metal from groups I-III), and the unit-cell parameters of the heterogeneous component MeX /SUB m/ (Me is a transition metal from groups IV-VIII). Only the AS-1 sites are stereospecific in the polymerization of ..cap alpha..-olefins and 1,3-dienes (isotactic polyolefins and 1,4-trans-polydienes form); the AS-2 sites are nonstereospecific in the polymerization of ..cap alpha..-olefins, but they form stereoregular 1,4-cis-polydienes; the AS-3 sites are nonstereospecific in the polymerization of both ..cap alpha..-olefins and 1,3-dienes. The phenomenon of stereoregularization in the polymerization of ..cap alpha..-olefins and 1,3-dienes is determined by the steric and electrostatic factors.

  19. Sulfur monoxide transfer from peri-substituted trisulfide-2-oxides to dienes: substituent effects, mechanistic studies and application in thiophene synthesis.

    PubMed

    Grainger, Richard S; Patel, Bhaven; Kariuki, Benson M; Male, Louise; Spencer, Neil

    2011-04-20

    Three peri-substituted trisulfide-2-oxides are prepared by treatment of 1,8-naphthalene dithiols with thionyl chloride and pyridine. The 1,2,3-trithiane-2-oxide ring adopts a sofa conformation in the solid state, with a pseudoaxial oxygen and evidence of ring strain (peri-interaction). Heating the trisulfide-2-oxides in the presence of a diene results in formal sulfur monoxide (SO) transfer to form unsaturated cyclic sulfoxides, along with a recyclable 1,8-naphthalene disulfide. The presence of o-methoxy or o-tert-butyl substituents on the naphthalene ring lowers the temperature and increases the rate at which SO transfer occurs. Trapping experiments and kinetic studies are consistent with the generation of triplet SO, followed by in situ trapping by diene. Transfer of SO also occurs upon irradiation at room temperature, but yields of sulfoxide are lower. Dehydration of the sulfoxides under Pummerer conditions gives thiophenes, including the naturally occurring thioperillene. Two dienes form thiophenes directly under the SO transfer conditions. The methodology is applied in a formal synthesis of the antiplatelet medication Plavix. PMID:21443185

  20. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

    SciTech Connect

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-15

    Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors

  1. Assessment of the role of in situ generated (E)-2,4-diene-valproic acid in the toxicity of valproic acid and (E)-2-ene-valproic acid in sandwich-cultured rat hepatocytes

    SciTech Connect

    Surendradoss, Jayakumar; Chang, Thomas K.H.; Abbott, Frank S.

    2012-11-01

    Valproic acid (VPA) undergoes cytochrome P450-mediated desaturation to form 4-ene-VPA, which subsequently yields (E)-2,4-diene-VPA by β-oxidation. Another biotransformation pathway involves β-oxidation of VPA to form (E)-2-ene-VPA, which also generates (E)-2,4-diene-VPA by cytochrome P450-mediated desaturation. Although the synthetic form of (E)-2,4-diene-VPA is more hepatotoxic than VPA as shown in various experimental models, there is no conclusive evidence to implicate the in situ generated (E)-2,4-diene-VPA in VPA hepatotoxicity. The present study investigated the effects of modulating the in situ formation of (E)-2,4-diene-VPA on markers of oxidative stress (formation of 2′,7′-dichlorofluorescein; DCF), steatosis (accumulation of BODIPY 558/568 C{sub 12}), necrosis (release of lactate dehydrogenase; LDH), and on cellular total glutathione (GSH) levels in sandwich-cultured rat hepatocytes treated with VPA or (E)-2-ene-VPA. Treatment with either of these chemicals alone increased each of the toxicity endpoints. In VPA-treated hepatocytes, (E)-2,4-diene-VPA was detected only at trace levels, even after phenobarbital (PB) pretreatment and there was no effect on the toxicity of VPA. Furthermore, pretreatment with a cytochrome P450 enzyme inhibitor, 1-aminobenzotriazole (1-ABT), did not influence the extent of VPA toxicity in both PB-pretreated and vehicle-pretreated hepatocytes. However, in (E)-2-ene-VPA-treated hepatocytes, PB pretreatment greatly enhanced the levels of (E)-2,4-diene-VPA and this was accompanied by a further enhancement of the effects of (E)-2-ene-VPA on DCF formation, BODIPY accumulation, LDH release, and GSH depletion. Pretreatment with 1-ABT reduced the concentrations of (E)-2,4-diene-VPA and the extent of (E)-2-ene-VPA toxicity; however, this occurred in PB-pretreated hepatocytes, but not in control hepatocytes. In conclusion, in situ generated (E)-2,4-diene-VPA is not responsible for the hepatocyte toxicity of VPA, whereas it

  2. The Labdane Ent-3-Acetoxy-Labda-8(17), 13-Dien-15-Oic Decreases Blood Pressure In Hypertensive Rats

    PubMed Central

    Simplicio, Janaina A.; Simão, Marilia R.; Ambrosio, Sergio R.; Tirapelli, Carlos R.

    2016-01-01

    Background Labdane-type diterpenes induce lower blood pressure via relaxation of vascular smooth muscle; however, there are no studies describing the effects of labdanes in hypertensive rats. Objective The present study was designed to investigate the cardiovascular actions of the labdane-type diterpene ent-3-acetoxy-labda-8(17), 13-dien-15-oic acid (labda-15-oic acid) in two-kidney 1 clip (2K-1C) renal hypertension. Methods Vascular reactivity experiments were performed in aortic rings isolated from 2K-1C and normotensive (2K) male Wistar rats. Nitrate/nitrite (NOx) measurement was performed in aortas by colorimetric assay. Blood pressure measurements were performed in conscious rats. Results Labda-15-oic acid (0.1-300 µmol/l) and forskolin (0.1 nmol/l - 1 µmol/l) relaxed endothelium-intact and endothelium-denuded aortas from both 2K-1C and 2K rats. Labda-15-oic acid was more effective at inducing relaxation in endothelium-intact aortas from 2K pre-contracted with phenylephrine when compared to the endothelium-denuded ones. Forskolin was more potent than labda-15-oic acid at inducing vascular relaxation in arteries from both 2K and 2K-1C rats. Labda-15-oic acid-induced increase in NOx levels was lower in arteries from 2K-1C rats when compared to 2K rats. Intravenous administration of labda-15-oic acid (0.3-3 mg/kg) or forskolin (0.1-1 mg/kg) induced hypotension in conscious 2K-1C and 2K rats. Conclusion The present findings show that labda-15-oic acid induces vascular relaxation and hypotension in hypertensive rats. PMID:27096521

  3. On the mechanism of the Di-. pi. -methane rearrangement of bicyclo(3. 2. 1)octa-2,6-diene: Deuterium labeling and generation of diradical intermediates via photolysis and thermolysis of appropriate azoalkanes

    SciTech Connect

    Adam, W.; Doerr, M. ); De Lucchi, O. )

    1989-07-05

    The direct (254 nm) and acetone-sensitized (300 nm) photolyses of 2,4,4-trideuteriobicyclo(3.2.1)octa-2,6-diene (D-1) gave exclusively 3,5,5-trideuteriotricyclo(4.2.0.0)oct-3-ene (D-7) and 2,6,6-trideuteriotricyclo(3.2.1.0)oct-3-ene (D-8) but no rearranged diene, namely, 2,8,8-trideuteriobicyclo(3.2.1)octa-2,6-diene (D-1{prime}). Pyrolysis (400{degree}C) and direct (334 nm) and benzophenone-sensitized (364 nm) photolyses of the azoalkane 3,5,5-trideuterio-9,10-diazatricyclo(4.4.0.0)deca-3,9-diene (D-9) afforded a mixture of tricyclooctenes D-7 (major product) and D-8 and bicyclooctadiene D-1, but no rearranged diene D-1{prime}. These three modes of denitrogenation of the azoalkane 2,2,7-trideuterio-4,5-diazatricyclo(4.3.1.0)deca-4,8-diene (D-10) led only to the tricyclooctene D-8 (major product) and equal amounts of the bicyclooctadienes D-1 and D-1{prime}. Distinct temperature profiles were observed in the product fingerprints of the direct photolysis (334 nm) of the azoalkanes 9 and 10. For both azoalkanes 9 and 10 the quantum yields of denitrogenation increased with rising temperature. In none of these transformations could bicyclo(3.3.0)octa-2,7-diene (2) be detected. These results imply that the di-{pi}-methane rearrangement of the bicyclooctadienes 1 (D-1) and the denitrogenations of the azoalkanes 9 (D-9) and 10 (D-10) are disjoint chemical events. The intervention of diazenyl diradicals (one-bond cleavage of the azoalkanes) is postulated to be responsible for this disparity. The intervention of cyclopropyldicarbinyl diradical 3 as bona fide reaction intermediate in the di-{pi}-methane rearrangement of bicyclooctadiene 1 is questioned.

  4. Ultraviolet photochemistry of buta-1,3- and buta-1,2-dienes: Laser spectroscopic absolute hydrogen atom quantum yield and translational energy distribution measurements

    SciTech Connect

    Hanf, A.; Volpp, H.-R.; Sharma, P.; Mittal, J. P.; Vatsa, R. K.

    2010-07-14

    Using pulsed H-atom Lyman-{alpha} laser-induced fluorescence spectroscopy along with a photolytic calibration approach, absolute H-atom product quantum yields of {phi}{sub H-b13d}=(0.32{+-}0.04) and {phi}{sub H-b12d}=(0.36{+-}0.04) were measured under collision-free conditions for the 193 nm gas-phase laser flash photolysis of buta-1,3- and buta-1,2-diene at room temperature, which demonstrate that nascent H-atom formation is of comparable importance for both parent molecules. Comparison of the available energy fraction, f{sub T-b13d}=(0.22{+-}0.03) and f{sub T-b12d}=(0.13{+-}0.01), released as H+C{sub 4}H{sub 5} product translational energy with results of impulsive and statistical energy partitioning modeling calculations indicates that for both, buta-1,3- and buta-1,2-diene, H-atom formation is preceded by internal conversion to the respective electronic ground state (S{sub 0}) potential energy surfaces. In addition, values of {sigma}{sub b-1,3-d-L{alpha}=}(3.5{+-}0.2)x10{sup -17} cm{sup 2} and {sigma}{sub b-1,2-d-L{alpha}=}(4.4{+-}0.2)x10{sup -17} cm{sup 2} for the previously unknown Lyman-{alpha} (121.6 nm) radiation photoabsorption cross sections of buta-1,3- and buta-1,2-diene in the gas-phase were determined.

  5. Theoretical study of free-radical-mediated 5-exo-trig cyclizations of chiral 3-substituted hepta-1,6-dienes.

    PubMed

    d'Antuono, Philippe; Fritsch, Alain; Ducasse, Laurent; Castet, Frédéric; James, Philippe; Landais, Yannick

    2006-03-16

    Free radical-mediated 5-exo-trig cyclizations of hepta-1,6-dienes incorporating allylsilane, alkyl and alkoxy analogues are modeled using correlated ab initio calculations. The structural, electronic and thermochemical properties of reactants, products and transition species involved in the key step of the radical cyclization process are analyzed and compared with those predicted by the Beckwith-Houk transition models. The product ratios are calculated from the Gibbs energy differences between the possible transition structures following the Curtin-Hammet principle and compared to experimental values. PMID:16526655

  6. Silver ion high pressure liquid chromatography provides unprecedented separation of sterols: application to the enzymatic formation of cholesta-5,8-dien-3 beta-ol.

    PubMed Central

    Ruan, B; Shey, J; Gerst, N; Wilson, W K; Schroepfer, G J

    1996-01-01

    We report that silver ion HPLC provides remarkable separations of C27 sterols differing only in the number or location of olefinic double bonds. This technique has been extended to LC-MS, analysis of purified components by GC, GC-MS, and 1H NMR, and to its use on a semipreparative scale. The application of this methodology for the demonstration of the catalysis, by rat liver microsomes, of the conversion of 7-dehydrocholesterol to cholesta-5,8-dien-3 beta-ol is also presented. PMID:8876182

  7. Brønsted Acid-Catalyzed Transfer Hydrogenation of Imines and Alkenes Using Cyclohexa-1,4-dienes as Dihydrogen Surrogates.

    PubMed

    Chatterjee, Indranil; Oestreich, Martin

    2016-05-20

    Cyclohexa-1,4-dienes are introduced to Brønsted acid-catalyzed transfer hydrogenation as an alternative to the widely used Hantzsch dihydropyridines. While these hydrocarbon-based dihydrogen surrogates do offer little advantage over established protocols in imine reduction as well as reductive amination, their use enables the previously unprecedented transfer hydrogenation of structurally and electronically unbiased 1,1-di- and trisubstituted alkenes. The mild procedure requires 5.0 mol % of Tf2NH, but the less acidic sulfonic acids TfOH and TsOH work equally well. PMID:27181437

  8. Bis(μ2-iso-propyl-imido-κ(2) N:N)bis-[(η(5)-cyclo-penta-dien-yl)(ethenolato-κO)titanium(IV)].

    PubMed

    Haehnel, Martin; Spannenberg, Anke; Rosenthal, Uwe

    2014-01-01

    The title dinuclear half-sandwich complex, [CpTi(OCH=CH2)(μ2-N-iPr)]2 (Cp = cyclo-penta-dien-yl; iPr = isopropyl), was ob-tained from the reaction of Cp2TiCl2, n-butyl-lithium and iso-propyl-amine in tetra-hydro-furan. Each Ti(IV) atom is coordinated by one Cp ligand, one vin-yloxy unit and two bridging imido groups in a strongly distorted tetra-hedral geometry. There are two half mol-ecules in the asymmetric unit, such that whole mol-ecules being generated by inversion symmetry. PMID:24526944

  9. Synthesis of 2-Aryl- and 2-Vinylpyrrolidines via Copper-Catalyzed Coupling of Styrenes and Dienes with Potassium β-Aminoethyl Trifluoroborates.

    PubMed

    Um, Chanchamnan; Chemler, Sherry R

    2016-05-20

    2-Arylpyrrolidines occur frequently in bioactive compounds, and thus, methods to access them from readily available reagents are valuable. We report a copper-catalyzed intermolecular carboamination of vinylarenes with potassium N-carbamoyl-β-aminoethyltrifluoroborates. The reaction occurs with terminal, 1,2-disubstituted, and 1,1-disubstituted vinylarenes bearing a number of functional groups. 1,3-Dienes are also good substrates, and their reactions give 2-vinylpyrrolidines. Radical clock mechanistic experiments are consistent with the presence of carbon radical intermediates and do not support participation of carbocations. PMID:27160334

  10. Chemistry of enol ethers. LXXXIV. Condensation of acetals of saturated aldehydes with 2-trimethylsilyloxy-1,3-dienes. Synthesis of /beta/-alkoxy-alkyl vinyl and divinyl ketones

    SciTech Connect

    Makin, S.M.; Nazarova, O.N.; Dymshakova, G.M.; Kundryutskova, L.A.

    1988-11-10

    The addition of the acetals of saturated aldehydes (formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and isobutyraldehyde) to 2-trimethylsilyloxy-4-methyl-1,3-pentadiene in the presence of aprotic acids (ZnCl/sub 2/, ZnBr/sub 2/, FeCl/sub 3/, SnCl/sub 4/, BF/sub 3/ /times/ OEt/sub 2/) takes place at positions 1, 2 of the diene system with the formation of /beta/-alkoxyalkyl vinyl ketones. The most effective catalysts of this reaction were stannic chloride and zinc bromide. The alkyl derivatives of divinyl ketones are formed when the obtained /beta/-alkoxyalkyl vinyl ketones are heated with p-toluenesulfonic acid.

  11. [Overexpressing 3-ketosteroid-Δ1-dehydrogenase for degrading phytosterols into androst-1,4-diene-3,17-dione].

    PubMed

    Zhang, Lele; Zhang, Xian; Shao, Minglong; Chen, Rongrong; Rao, Zhiming; Li, Hu; Xu, Zhenghong

    2015-11-01

    We constructed plasmid pMTac to overexpress 3-ketosteroid-Δ1-dehydrogenase (KSDD) in Mycobacterium neoaurum JC-12 for improving androst-1,4-diene-3,17-dione (ADD) production. To construct pMTac, pACE promoter on pMF41 was replaced by tac promoter, and then four recombinants were constructed, which were M. neoaurum JC-12/pMF41-gfp, M. neoaurum JC-12/pMTac-gfp, M. neoaurum JC-12/pMF41-ksdd and M. neoaurum JC-12/pMTac-ksdd. Fluorescence detection results show that much more green fluorescent protein (GFP) was expressed in M. neoaurum JC-12/pMTac-ksdd than M. neoaurum JC-12/pMF41-ksdd. The activity of KSDD was 2.41 U/mg in M. neoaurum JC-12/pMTac-ksdd, 6.53-fold as that of M. neoaurum JC-12 and 4.36-fold as that of M. neoaurum JC-12/pMF41-ksdd. In shake flask fermentation, ADD production of M. neoaurum JC-12/pMTac-ksdd was 5.94 g/L, increased about 22.2% compared to the original strain M. neoaurum JC-12 and 12.7% to M. neoaurum JC-12/pMF41-ksdd. AD (4-androstene-3,17-dione) production of JC-12/pMTac-ksdd was 0.17 g/L, decreased 81.5% compared to M. neoaurum JC-12 and 71.2% to M neoaurum JC-12/pMF41-ksdd. In the 5 L fermenter, 20 g/L phytosterols was used as substrate, ADD production of M. neoaurum JC-12/pMTac-ksdd was improved to 10.28 g/L. pMTac is favorable for expressing KSDD in M. neoaurum JC-12, and overexpression of KSDD has beneficial effect on ADD producing, and it is the highest level ever reported using fermentation method in M. neoaurum. PMID:26939442

  12. Expression of Delta(12) fatty acid desaturase during the induced accumulation of the antifungal diene in avocado fruits.

    PubMed

    Wang, Xuejun; Beno-Moualem, Delila; Kobiler, Ilana; Leikin-Frenkel, Alicia; Lichter, Amnon; Prusky, Dov

    2004-11-01

    SUMMARY The preformed (Z,Z)-1-acetoxy-2-hydroxy-4-oxo-heneicosa-12,15-diene (AFD) is the most active antifungal compound in avocado; it affects the quiescence of Colletotrichum gloeosporioides in unripe fruit. One of the genes encoding Delta(12) fatty acid desaturase (avfad12) was hypothesized to take part in the biosynthesis of AFD, and its expression pattern and enzymatic activity were determined in relation to the content of AFD. Using avfad12-3 as a probe, high levels of expression were detected in young fruits and leaves, where the level of AFD was highest. In contrast, Northern analysis of RNA from mature leaves and fruits showed no transcripts from the avfad12 gene family and lower AFD content. The transcripts from the avfad12 gene family, the enzymatic activity of Delta(12) fatty acid desaturase, and the level of AFD in unripe-resistant fruits increased transiently when the fruits were inoculated with C. gloeosporioides or exposed to ethylene (40 microL/L), low temperature (4 degrees C) or 1 mm H(2)O(2), but ripe fruits were not affected. The effect of H(2)O(2) on the transcripts from the avfad12 gene family is of specific importance, because reactive oxygen species were produced by unripe-resistant host fruit soon after inoculation of C. gloeosporioides. In addition, the fungus itself produced H(2)O(2) in culture medium at pH 5.0, which is similar to the pH of unripe-resistant fruit, but not at pH 7.0. Treatments that enhanced Delta(12) fatty acid desaturase activity increased the concentration of the AFD precursor, linoleic acid, and its incorporation into AFD; these treatments also caused a delay in decay development. The present results demonstrate temporal relationships among the transcripts from the avfad12 gene family, the synthesis of the precursor of AFD (linoleic acid), the AFD content and quiescence of C. gloeosporioides in unripe fruits. PMID:20565631

  13. Reactivity Study of Pyridyl-Substituted 1-Metalla-2,5-diaza-cyclopenta-2,4-dienes of Group 4 Metallocenes.

    PubMed

    Becker, Lisanne; Reiß, Fabian; Altenburger, Kai; Spannenberg, Anke; Arndt, Perdita; Jiao, Haijun; Rosenthal, Uwe

    2016-07-25

    In this work the reactivity of 1-metalla-2,5-diaza-cyclopenta-2,4-dienes of group 4 metallocenes, especially of the pyridyl-substituted examples, towards small molecules is investigated. The addition of H2 , CO2 , Ph-C≡N, 2-py-C≡N, 1,3-dicyanobenzene or 2,6-dicyanopyridine results in exchange reactions, which are accompanied by the elimination of a nitrile. For CO2 , a coordination to the five-membered cycle occurs in case of Cp*2 Zr(N=C(2-py)-C(2-py)=N). A 1,4-diaza-buta-1,3-diene complex is formed by H-transfer in the conversion of the analogous titanocene compound with CH3 -C≡N, PhCH2 -C≡N or acetone. For CH3 -C≡N a coupling product of three acetonitrile molecules is established additionally. In order to split off the metallocene from the coupled nitriles, we examined reactions with HCl, PhPCl2 , PhPSCl2 and SOCl2 . In the last case, the respective thiadiazole oxides and the metallocene dichlorides were obtained. A subsequent reaction produced thiadiazoles. PMID:27312375

  14. Functional Identification of Valerena-1,10-diene Synthase, a Terpene Synthase Catalyzing a Unique Chemical Cascade in the Biosynthesis of Biologically Active Sesquiterpenes in Valeriana officinalis*

    PubMed Central

    Yeo, Yun-Soo; Nybo, S. Eric; Chittiboyina, Amar G.; Weerasooriya, Aruna D.; Wang, Yan-Hong; Góngora-Castillo, Elsa; Vaillancourt, Brieanne; Buell, C. Robin; DellaPenna, Dean; Celiz, Mary Dawn; Jones, A. Daniel; Wurtele, Eve Syrkin; Ransom, Nick; Dudareva, Natalia; Shaaban, Khaled A.; Tibrewal, Nidhi; Chandra, Suman; Smillie, Troy; Khan, Ikhlas A.; Coates, Robert M.; Watt, David S.; Chappell, Joe

    2013-01-01

    Valerian is an herbal preparation from the roots of Valeriana officinalis used as an anxiolytic and sedative and in the treatment of insomnia. The biological activities of valerian are attributed to valerenic acid and its putative biosynthetic precursor valerenadiene, sesquiterpenes, found in V. officinalis roots. These sesquiterpenes retain an isobutenyl side chain whose origin has been long recognized as enigmatic because a chemical rationalization for their biosynthesis has not been obvious. Using recently developed metabolomic and transcriptomic resources, we identified seven V. officinalis terpene synthase genes (VoTPSs), two that were functionally characterized as monoterpene synthases and three that preferred farnesyl diphosphate, the substrate for sesquiterpene synthases. The reaction products for two of the sesquiterpene synthases exhibiting root-specific expression were characterized by a combination of GC-MS and NMR in comparison to the terpenes accumulating in planta. VoTPS7 encodes for a synthase that biosynthesizes predominately germacrene C, whereas VoTPS1 catalyzes the conversion of farnesyl diphosphate to valerena-1,10-diene. Using a yeast expression system, specific labeled [13C]acetate, and NMR, we investigated the catalytic mechanism for VoTPS1 and provide evidence for the involvement of a caryophyllenyl carbocation, a cyclobutyl intermediate, in the biosynthesis of valerena-1,10-diene. We suggest a similar mechanism for the biosynthesis of several other biologically related isobutenyl-containing sesquiterpenes. PMID:23243312

  15. Functional Analysis of Amorpha-4,11-Diene Synthase (ADS) Homologs from Non-Artemisinin-Producing Artemisia Species: The Discovery of Novel Koidzumiol and (+)-α-Bisabolol Synthases.

    PubMed

    Muangphrom, Paskorn; Seki, Hikaru; Suzuki, Munenori; Komori, Aya; Nishiwaki, Mika; Mikawa, Ryota; Fukushima, Ery Odette; Muranaka, Toshiya

    2016-08-01

    The production of artemisinin, the most effective antimalarial compound, is limited to Artemisia annua. Enzymes involved in artemisinin biosynthesis include amorpha-4,11-diene synthase (ADS), amorpha-4,11-diene 12-monooxygenase (CYP71AV1) and artemisinic aldehyde Δ(11)13 reductase (DBR2). Although artemisinin and its specific intermediates are not detected in other Artemisia species, we reported previously that CYP71AV1 and DBR2 homologs were expressed in some non-artemisinin-producing Artemisia plants. These homologous enzymes showed similar functions to their counterparts in A. annua and can convert fed intermediates into the following products along the artemisinin biosynthesis in planta These findings suggested a partial artemisinin-producing ability in those species. In this study, we examined genes highly homologous to ADS, the first committed gene in the pathway, in 13 Artemisia species. We detected ADS homologs in A. absinthium, A. kurramensis and A. maritima. We analyzed the enzymatic functions of all of the ADS homologs after obtaining their cDNA. We found that the ADS homolog from A. absinthium exhibited novel activity in the cyclization of farnesyl pyrophosphate (FPP) to koidzumiol, a rare natural sesquiterpenoid. Those from A. kurramensis and A. maritima showed similar, but novel, activities in the cyclization of FPP to (+)-α-bisabolol. The unique functions of the novel sesquiterpene synthases highly homologous to ADS found in this study could provide insight into the molecular basis of the exceptional artemisinin-producing ability in A. annua. PMID:27273626

  16. Enantioselective Arylation of N-Tosylimines by Phenylboronic Acid Catalysed by a Rhodium/Diene Complex: Reaction Mechanism from Density Functional Theory.

    PubMed

    Sieffert, Nicolas; Boisson, Julien; Py, Sandrine

    2015-06-26

    A DFT study of the reaction mechanism of the rhodium-catalysed enantioselective arylation of (E)-N-propylidene-4-methyl-benzenesulfonamide by phenylboronic acid [Lin et al J. Am. Chem. Soc. 2011, 133, 12394] is reported. The catalyst ([{Rh(OH)(diene)}2]) includes a chiral diene ligand and the reaction is conducted in 1,4-dioxane in the presence of drying agents (4 Å molecular sieves). Because phenylboronic acid is in equilibrium with phenylboroxin and water under the reaction conditions, three catalytic cycles are proposed that differ in the way the transmetallation and the release of the product are brought about, depending on the availability of phenylboronic acid, water and boroxin in the reaction medium. Based on computations, a new mechanism for the title reaction is proposed, in which phenylboronic acid plays the double role of "aryl source" and proton donor. This path does not require the presence of adventitious water molecules, in keeping with a reaction conducted in a dry medium. Comparisons with the generally accepted mechanism for arylation of enones proposed by Hayashi and co-workers (J. Am. Chem. Soc. 2002, 124, 5052) show that the latter mechanism is less favourable and is not expected to operate in the case of the N-tosylimine substrate considered herein. Finally, the possibility that phenylboroxin is the aryl source has also been investigated, but is not found to be competitive. PMID:26032123

  17. Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

    SciTech Connect

    Zhao Jing; Liang Jingjing; Pan Yingli; Zhang Yong; Jia Dingxian

    2011-06-15

    Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en){sub 2}(dien)({eta}{sup 2}-SbSe{sub 4})] (Ln=Ce(1a), Nd(1b)), [Ln(en){sub 2}(dien)(SbSe{sub 4})] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)({mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4})]{sub {infinity}} (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)({eta}{sup 2}-SbSe{sub 4})] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe{sub 4}]{sup 3-} acts as a monodentate ligand mono-SbSe{sub 4}, a bidentate chelating ligand {eta}{sup 2}-SbSe{sub 4} or a tridentate bridging ligand {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} to the lanthanide(III) center depending on the Ln{sup 3+} ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with E{sub g} between 2.08 and 2.51 eV. - Graphical Abstract: Two structural types of lanthanide(III) selenidoantimonates are formed in both en-dien and en-trien mixed polyamines across lanthanide series, indicating the lanthanide contraction effect on the structures of the lanthanide(III) selenidoantimonates. Highlights: > Two structural types of lanthanide selenidoantimonates are prepared across the lanthanide series in both Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) systems. > The [SbSe{sub 4}]{sup 3-} anion acts as a mono-SbSe{sub 4}, a {eta}{sup 2}-SbSe{sub 4} or a {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} ligand to the Ln{sup 3+} ions. > The soft base ligand [SbSe{sub 4}]{sup 3-} can be controlled to coordinate to the Ln{sup 3+} ions with en+dien and en+trien as co-ligands.

  18. Thermoplastic vulcanizate nanocomposites based on polypropylene/ethylene propylene diene terpolymer (PP/EPDM) prepared by reactive extrusion

    NASA Astrophysics Data System (ADS)

    Mirzadeh, Amin

    using the solvent extraction and gravimetry technique. Additionally, the effect of continuity on rheological behaviour of TPE nanocomposites was investigated. The ultimate goal in this field is to maximize the rubber like behaviour by controlling the blend morphology and the level of crosslinking. Therefore, this study also covers the effects of nanoclay presence and its dispersion level on the crosslinking reaction of thermoplastic vulcanizate nanocomposites prepared by reactive extrusion. Here, the rubber phase was dynamically vulcanized using dimethylol phenolic resin or octylphenol-formaldehyde resin along with stannous chloride dihydrate as the catalyst. In the present study, the dynamic vulcanization of the prepared TPVs and corresponding nanocomposites are characterized using different criteria, such as gel content, viscosity and normalized storage modulus in the time sweep tests, nuclear magnetic resonance (NMR) signal line width, bound curative content and residual diene concentration. The combination of the above parameters appears to be sufficient to provide a clear description of the systems. The last part of the present study is devoted to find how the dispersion level of nanoclay and consequently the extent of crosslinking change the rubber like behaviour and the morphology of the prepared TPVs. Therefore, recently developed method named temperature scanning stress relaxation (TSSR) was used to estimate the rubber indices of TPVs and TPV nanocomposites. The mentioned method also successfully provided information about the extent of crosslinking reaction. It is shown that the rubber like behaviour of the blends containing 50wt% and 60wt% of EPDM in which morphological studies suggest the presence of the rubber droplets in vicinity of irregular shape rubber particles with a low level of interconnectivity, correlates with the rubber droplet size. Therefore, the nanoclay presence affects the rubber index values mainly through its effect on the size of the

  19. Neolignans with a Rare 2-Oxaspiro[4.5]deca-6,9-dien-8-one Motif from the Stem Bark of Cinnamomum subavenium.

    PubMed

    Lai, Yongji; Liu, Tingting; Sa, Rongjian; Wei, Xialan; Xue, Yongbo; Wu, Zhaodi; Luo, Zengwei; Xiang, Ming; Zhang, Yonghui; Yao, Guangmin

    2015-07-24

    Two pairs of racemic spirodienone neolignans with a rare 2-oxaspiro[4.5]deca-6,9-dien-8-one motif, named (±)-subaveniumins A (1) and B (2), were isolated from the bark of Cinnamomum subavenium. The chiral separation of the (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers was accomplished via high-performance liquid chromatography on a chiral column. Their structures were elucidated using single-crystal X-ray diffraction and spectroscopic analyses (UV, IR, HRESIMS, and 1D and 2D NMR). The absolute configurations of the enantiomers were determined by comparing the experimental and calculated electronic circular dichroic spectra. The (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers exhibited moderate inhibitory effects against NO production in RAW264.7 mouse macrophages induced by lipopolysaccharide, with IC50 values of 17.9, 5.6, 15.1, and 4.3 μM, respectively. PMID:26087384

  20. Metalloporphyrin-Based Hypercrosslinked Polymers Catalyze Hetero-Diels-Alder Reactions of Unactivated Aldehydes with Simple Dienes: A Fascinating Strategy for the Construction of Heterogeneous Catalysts.

    PubMed

    Dou, Zhiyu; Xu, Li; Zhi, Yongfeng; Zhang, Yuwei; Xia, Hong; Mu, Ying; Liu, Xiaoming

    2016-07-11

    We describe a novel and intriguing strategy for the construction of efficient heterogeneous catalysts by hypercrosslinking catalyst molecules in a one-pot Friedel-Crafts alkylation reaction. The new hypercrosslinked polymers (HCPs) as porous solid catalysts exhibit the combined advantages of homogeneous and heterogeneous catalysis, owing to their high surface area, good stability, and tailoring of catalytic centers on the frameworks. Indeed, a new class of metalloporphyrin-based HCPs were successfully synthesized using modified iron(III) porphyrin complexes as building blocks, and the resulting networks were found to be excellent recyclable heterogeneous catalysts for the hetero-Diels-Alder reaction of unactivated aldehydes with 1,3-dienes. Moreover, this new strategy showed wide adaptability, and many kinds of homogeneous-like solid-based catalysts with high catalytic performance and excellent recyclability were also constructed. PMID:27147500

  1. Intense Ground-State Charge-Transfer Interactions in Low-Bandgap, Panchromatic Phthalocyanine-Tetracyanobuta-1,3-diene Conjugates.

    PubMed

    Sekita, Michael; Ballesteros, Beatriz; Diederich, François; Guldi, Dirk M; Bottari, Giovanni; Torres, Tomás

    2016-04-25

    A cycloaddition-retroelectrocyclization reaction between tetracyanoethylene and two zinc phthalocyanines (Zn(II) Pcs) bearing one or four anilino-substituted alkynes has been used to install a strong, electron-accepting tetracyanobuta-1,3-diene (TCBD) between the electron-rich Zn(II) Pc and aniline moieties. A combination of photophysical, electrochemical, and spectroelectrochemical investigations with the Zn(II) Pc-TCBD-aniline conjugates, which present panchromatic absorptions in the visible region extending all the way to the near infrared, show that the formal replacement of the triple bond by TCBD has a dramatic effect on their ground- and excited-state features. In particular, the formation of extremely intense, ground-state charge-transfer interactions between Zn(II) Pc and the electron-accepting TCBD were observed, something unprecedented not only in Pc chemistry but also in TCBD-based porphyrinoid systems. PMID:27010677

  2. A New Series of Complexes Possessing Rare “Tertiary” Sulfonamide Nitrogen-to-Metal Bonds of Normal Length: fac-[Re(CO)3(N(SO2R)dien)]PF6 Complexes with Hydrophilic Sulfonamide Ligands

    PubMed Central

    Abhayawardhana, Pramuditha L.; Marzilli, Patricia A.; Fronczek, Frank R.

    2014-01-01

    Tertiary sulfonamide nitrogen-to-metal bonds of normal length are very rare. We recently discovered such a bond in one class of fac-[Re(CO)3(N(SO2R)(CH2Z)2)]n complexes (Z = 2-pyridyl) with N(SO2R)dpa ligands derived from di-(2-picolyl)amine (N(H)dpa). fac-[M(CO)3(N(SO2R)(CH2Z)2)]n agents (M = 186/188Re, 99mTc) could find use as radiopharmaceutical bioconjugates when R is a targeting moiety. However, the planar, electron-withdrawing 2-pyridyl groups of N(SO2R)dpa destabilize the ligand to base and create relatively rigid chelate rings, raising the possibility that the rare M– N(sulfonamide) bond is an artifact of a restricted geometry. Also, the hydrophobic 2-pyridyl groups could cause undesirable accumulation in the liver, limiting future use in radiopharmaceuticals. Our goal is to identify a robust, hydrophilic, and flexible N(CH2Z)2 chelate framework. New C2-symmetric ligands, N(SO2R)(CH2Z)2 with (Z = CH2NH2; R = Me, dmb, or tol), were prepared by treating N(H)dien(Boc)2, a protected diethylenetriamine (N(H)dien) derivative, with methanesulfonyl chloride (MeSO2Cl), 3,5-dimethylbenzenesulfonyl chloride (dmbSO2Cl), and 4-methylbenzenesulfonyl chloride (tolSO2Cl). Treatment of fac-[Re(CO)3(H2O)3]+ with these ligands, designated as N(SO2R)dien, afforded new fac-[Re(CO)3(N(SO2R)dien)]PF6 complexes. Comparing the fac-[Re(CO)3(N(SO2Me)dien)]PF6 and fac-[Re(CO)3(N(SO2Me)dpa)]PF6 complexes, we find that the ReI–N(sulfonamide) bonds are normal in length and statistically identical and that the methyl 13C NMR signal has an unusually upfield shift compared to that in the free ligand. We attribute this unusual upfield shift to the fact that the sulfonamide N undergoes an sp2-to-sp3 rehybridization upon coordination to ReI in both complexes. Thus, the sulfonamide N of N(SO2R)dien ligands is a good donor, even though the chelate rings are conformationally flexible. Addition of the strongly basic and potentially monodentate ligand, 4-dimethylaminopyridine, did not affect

  3. Crystal structure of 4,4-di-bromo-1-(3,4-di-meth-oxy-phen-yl)-2-aza-buta-1,3-diene-1-carbo-nitrile.

    PubMed

    Chaabene, Marwa; Khatyr, Abderrahim; Knorr, Michael; Askri, Moheddine; Rousselin, Yoann; Kubicki, Marek M

    2016-08-01

    The title compound, C12H10Br2N2O2, represents an example of a planar π-con-jugated 2-aza-butadiene mol-ecule, which is both an inter-esting starting material for further organic transformations and a potential ligand in organometallic coordination chemistry. Its metric mol-ecular parameters are typical for the family of 2-aza-buta-1,3-dienes not substituted at the (CH) 3-position. In the crystal, the almost planar (r.m.s. deviation = 0.0658 Å) aza-diene mol-ecules form one-dimensional double-wide ribbons through inter-molecular halogen bonds (C-Br⋯O and C-Br⋯Br-C), which then stack in a slipped manner through weak C-H⋯Br and π-π inter-actions to generate a three-dimensional network. PMID:27536405

  4. In situ reactive compatibilization of polypropylene/ethylene-propylene-diene monomer thermoplastic vulcanizate by zinc dimethacrylate via peroxide-induced dynamic vulcanization.

    PubMed

    Chen, Yukun; Xu, Chuanhui; Liang, Xingquan; Cao, Liming

    2013-09-12

    This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using zinc dimethacrylate (ZDMA) as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With the incorporation of 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength, tear strength, elongation at break, and hardness of PP/EPDM/ZDMA TPV were increased from 5.3 MPa, 31.3 kN/m, 222%, and 78 up to 11.2 MPa, 64.2 kN/m, 396%, and 83, respectively. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacted with EPDM and PP during peroxide-induced dynamic vulcanization. A peculiar phase structure that rubber particles were surrounded and "bonded" by a thick transition zone that contained numerous of nanoparticles with dimensions of about 20-30 nm was observed from transmission electron microscopy. Scanning electron microscopy results confirmed that incorporation of ZDMA reduced the size of the cross-linked EPDM particles. Moreover, we found that the compatibilized TPV showed a higher tan δ peak temperature for EPDM phase and a lower tan δ peak temperature for PP phase. The suggested method for in situ reactive compatibilization of PP and EPDM offers routes to the design of new TPV-based technical products for diversified applications. PMID:23981036

  5. Morphology study of peroxide-induced dynamically vulcanized polypropylene/ethylene-propylene-diene monomer/zinc dimethacrylate blends during tensile deformation.

    PubMed

    Chen, Yukun; Xu, Chuanhui; Cao, Liming; Wang, Yanpeng; Fang, Liming

    2013-06-27

    Polypropylene (PP)/ethylene-propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blend (EPDM/PP ratio of 30/70) with remarkable extensibility was successfully prepared via peroxide dynamic vulcanization. The uniaxial tensile properties, crystallization behavior, structure, and morphology during stretching were investigated. The tensile process study showed that the PP/EPDM/ZDMA blend exhibited the rubbery-like behavior with an elongation beyond 600%. The ZDMA graft-product domain increased the compatibility and interfacial adhesion between rubber and PP phases, while it reduced the crystallinity of the PP phase. On the basis of TEM and SEM analyses, we found that the cross-linked rubber particles could be elongated and oriented along the tensile direction, whereas the ZDMA graft-product domain "encapsulated" rubber phase together, acting as a "bridge" between elongated rubber phases and the PP phase during uniaxial stretching. The stress could be effectively transferred from the PP phase to the numerous elongated rubber phases due to the excellent compatibility and interfacial adhesion between rubber and PP phases, resulting in the rubbery-like behavior. PMID:23742700

  6. Enhanced Production of Androst-1,4-Diene-3,17-Dione by Mycobacterium neoaurum JC-12 Using Three-Stage Fermentation Strategy

    PubMed Central

    Shao, Minglong; Zhang, Xian; Rao, Zhiming; Xu, Meijuan; Yang, Taowei; Li, Hui; Xu, Zhenghong

    2015-01-01

    To improve the androst-1,4-diene-3,17-dione (ADD) production from phytosterol by Mycobacterium neoaurum JC-12, fructose was firstly found favorable as the initial carbon source to increase the biomass and eliminate the lag phase of M. neoaurum JC-12 in the phytosterol transformation process. Based on this phenomenon, two-stage fermentation by using fructose as the initial carbon source and feeding glucose to maintain strain metabolism was designed. By applying this strategy, the fermentation duration was decreased from 168 h to 120 h with the ADD productivity increased from 0.071 g/(L·h) to 0.108 g/(L·h). Further, three-stage fermentation by adding phytosterol to improve ADD production at the end of the two-stage fermentation was carried out and the final ADD production reached 18.6 g/L, which is the highest reported ADD production using phytosterol as substrate. Thus, this strategy provides a possible way in enhancing the ADD production in pharmaceutical industry. PMID:26352898

  7. Growth and characterization of a new organic nonlinear optical crystal: 1-(3-Nitrophenyl)-5-phenylpenta-2,4-dien-1-one

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Kumar, P. Ajay; Venugopal Rao, S.; Bhagavannarayana, G.

    2015-08-01

    Organic nonlinear optical single crystal of 1-(3-Nitrophenyl)-5-phenylpenta-2,4-dien-1-one (Ci3NC) with dimensions 25×15×10 mm3 was successfully grown for the first time by the slow evaporation solution growth technique (SEST). The structural perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements, and it was found that the crystalline perfection is reasonably good having very low angle (tilt angle ≤1‧) internal structural grain boundary. Thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder test with Nd:YAG laser radiation shows second harmonic generation which is about 7 times that of urea. The optical transmittance window and the lower cutoff wavelength of the Ci3NC have been identified by UV-vis-NIR studies. Third-order nonlinear optical (NLO) response of Ci3NC has been examined using Z-scan technique with femtosecond (fs), MHz pulses at wavelengths of 870 nm and 900 nm. Various NLO coefficients such as two-photon absorption (2PA) coefficient (β), three photon absorption (3PA) coefficient (γ), and nonlinear refractive index (η2) were evaluated.

  8. endo/exo stereoselectivity in Diels-Alder reactions of α,β-dialkylated conjugated enals to cyclic 1,3-dienes: intermediates in the synthesis of (-)-β-santalol and its analogs.

    PubMed

    Chapuis, Christian; Skuy, David; de Saint Laumer, Jean-Yves; Brauchli, Robert

    2014-10-01

    Highly exo-selective [4+2] cycloadditions of cyclopenta-1,3-diene 2a to α,β-dialkyl conjugated enals 5 are compared with the analogous endo-favored Diels-Alder reaction of cyclohexa-1,3-diene 7. The exo-stereoselectivity is lower in the homologous case of methylcyclopenta-1,3-diene 9. This diastereoselectivity is discussed either in terms of a retro-homo-Diels-Alder reaction, associated with thermodynamic control, or with respect to either a competing hetero-Diels-Alder/Claisen or Cope domino pathway, or retro-Claisen/retro-hetero-Diels-Alder of the endo-homo-cycloadducts. These hypothetical mechanisms have been examined by DFT calculations at the MPW1K(CH2 Cl2 )/6-31+G** level of theory for the AlCl3 -mediated cycloadditions of 5d to 2a and 7. Application of Corey's methodology to the γ-halogeno-α-methyl-substituted dienophiles 5a and 5b allowed an enantioselective preparation of known and useful intermediates for the synthesis of either the naturally occurring (-)-β-santalol or its potentially olfactive structural analogs. PMID:25329781

  9. Dual Regulation of Cell Death and Cell Survival upon Induction of Cellular Stress by Isopimara-7,15-Dien-19-Oic Acid in Cervical Cancer, HeLa Cells In vitro

    PubMed Central

    Abu, Nadiah; Yeap, Swee K.; Pauzi, Ahmad Z. Mat; Akhtar, M. Nadeem; Zamberi, Nur R.; Ismail, Jamil; Zareen, Seema; Alitheen, Noorjahan B.

    2016-01-01

    The Fritillaria imperialis is an ornamental flower that can be found in various parts of the world including Iraq, Afghanistan, Pakistan, and the Himalayas. The use of this plant as traditional remedy is widely known. This study aims to unveil the anti-cancer potentials of Isopimara-7,15-Dien-19-Oic Acid, extracted from the bulbs of F. imperialis in cervical cancer cell line, HeLa cells. Flow cytometry analysis of cell death, gene expression analysis via cDNA microarray and protein array were performed. Based on the results, Isopimara-7,15-Dien-19-Oic acid simultaneously induced cell death and promoted cell survival. The execution of apoptosis was apparent based on the flow cytometry results and regulation of both pro and anti-apoptotic genes. Additionally, the regulation of anti-oxidant genes were up-regulated especially thioredoxin, glutathione and superoxide dismutase- related genes. Moreover, the treatment also induced the activation of pro-survival heat shock proteins. Collectively, Isopimara-7,15-Dien-19-Oic Acid managed to induce cellular stress in HeLa cells and activate several anti- and pro survival pathways. PMID:27065873

  10. Administration d’anti-inflammatoires non stéroïdiens aux enfants ayant des antécédents de sibilance

    PubMed Central

    Sih, Kendra; Goldman, Ran D.

    2016-01-01

    Résumé Question Un enfant qui fréquente ma clinique s’est récemment fait une entorse à la cheville et il éprouve de la douleur et de la difficulté à supporter son poids sur la jambe affectée. Sa mère lui donne de l’acétaminophène parce qu’on lui a dit de ne jamais utiliser d’anti-inflammatoires non stéroïdiens (AINS) en raison de son asthme contrôlé par pharmacologie. L’asthme chez un enfant est-il une contre-indication à l’administration d’AINS? La maladie respiratoire exacerbée par les AINS existe-t-elle comme entité réelle? Réponse Les AINS sont des médicaments analgésiques et antipyrétiques efficaces. La maladie respiratoire exacerbée par des AINS a été décrite chez des adultes ayant certains facteurs de prédisposition, mais n’a pas été clairement identifiée chez un grand nombre d’enfants. Les AINS peuvent donc être recommandés aux enfants ayant une sibilance connue qui n’ont pas d’antécédents de maladie respiratoire déclenchée par des AINS. PMID:27521406

  11. Phase I Study of the Synthetic Triterpenoid, 2-Cyano-3, 12-Dioxoolean-1, 9-Dien-28-Oic Acid (CDDO), in Advanced Solid Tumors

    PubMed Central

    Speranza, Giovanna; Gutierrez, Martin E.; Kummar, Shivaani; Parker, Robert J.; Collins, Jerry; Yu, Yunkai; Cao, Liang; Murgo, Anthony J.; Doroshow, James H.; Chen, Alice

    2015-01-01

    Background The triterpenoid 2-Cyano-3, 12-Dioxoolean-1, 9-Dien-28-Oic Acid (CDDO, previously RTA-401) is a multifunctional molecule that controls cellular growth and differentiation. It is capable of activating the transcription factor peroxisome proliferator activator receptor-γ (PPARγ) and inducing apoptosis in malignant cells in vitro and in vivo. We conducted a phase I dose-escalation study to determine the toxicity, the maximum tolerated dose, and the pharmacokinetics and pharmacodynamics of CDDO, administered as a 5-day continuous infusion every 28 days in patients with advanced cancers. Methods An accelerated titration design was followed, with one patient per cohort entered, and doses ranging from 0.6 mg/m2/hr to 38.4 mg/m2/hr. Pharmacokinetics of CDDO was assessed and cleaved poly (ADP-ribose) polymerase (c-PARP), as a marker of apoptosis, was measured in peripheral blood mononuclear cells to assess drug effect. Results Seven patients, one patient per dose level up to dose level 7 (38.4 mg/m2/hr), were enrolled and received a total of 11 courses of treatment. Cmax increased proportionally with dose. Preclinically determined efficacious blood level (1 μM) of drug was attained at the highest dose level. One patient, at dose level 6, experienced grade 2 mucositis, nausea, vomiting, and anorexia. Four patients, on different dose levels, developed thromboembolic events subsequently considered as dose-limiting toxicity. No anti-tumor activity was noted. Conclusion A causal relationship of observed thromboembolic events to CDDO was considered possible but could not be established. Because of the adverse events and the development of an orally bioavailable derivative compound, CDDO methyl ester, this trial was terminated. PMID:21805353

  12. Postnatal decline in gonadal secretion of dehydroepiandrosterone and 3 beta-hydroxyandrosta-5,7-dien-17-one in the newborn foal.

    PubMed

    Raeside, J I; Renaud, R L; Christie, H L

    1997-11-01

    Dehydroepiandrosterone (DHEA) and 3 beta-hydroxyandrosta-5,7-dien-17-one (7-dehydro-DHEA) are secreted in large quantities by the remarkably hypertrophied fetal gonads of both sexes in the pregnant mare. Their secretion serves as the fetal component of a feto-placental unit for oestrogen production in equine pregnancies. They are secreted in large amounts but show a decline in late pregnancy when the fetal gonads regress and levels of oestrogens in the mare fall as a consequence. We have examined the levels of these precursor steroids in the newborn foal in the first days after birth. DHEA and 7-dehydro-DHEA were measured in peripheral plasma in a direct RIA with a DHEA antibody which cross-reacts with 7-dehydro DHEA (> 150%). Subsequent studies were performed with solid-phase extraction, separation of unconjugated from conjugated steroids, and HPLC fractionation followed by RIA. Detection on HPLC at 254 and 280 nm was compared with results from RIA. It was concluded that DHEA is the major steroid produced by the gonads at birth. The concentrations are highly variable in the first day of postnatal life (70.45 +/- 63.06 ng/ml, n = 52) and decline rapidly to < 2 ng/ml (n = 6) at 96 h after birth. At this time the sulphate form is also seen, with an increasing ratio of DHEAS/DHEA as the value for total DHEA falls. The mechanism and significance of the apparent abrupt decline in gonadal steroidogenesis in the newborn foal remain unknown. PMID:9415062

  13. Heats of formation of [2.2]paracyclophane-1-ene and [2.2]paracyclophane-1,9-diene - an experimental study.

    PubMed

    de Meijere, Armin; Kozhushkov, Sergei I; Rauch, Karsten; Schill, Heiko; Verevkin, Sergey P; Kümmerlin, Martin; Beckhaus, Hans-Dieter; Rüchardt, Christoph; Yufit, Dmitrii S

    2003-12-10

    The enthalpies of formation [Delta(g)] of tricyclo[8.2.2.2(4,7)]hexadeca-1(13),2,4(16),5,7(15),10(14),11-heptaene (2, 1,2-dehydro[2.2]paracyclophane or [2.2]paracyclophane-1-ene) and tricyclo[8.2.2.2(4,7)]hexadeca-1(13),2,4(16),5,7(15),8,10(14),11-octaene (3, 1,2,9,10-dehydro[2.2]paracyclophane or [2.2]paracyclophane-1,9-diene) have been determined by measuring their heats of combustion in a microcalorimeter and their heats of sublimation by the transpiration method. Values of the strain energies (SE) [SE(2) = 34.7 kcal mol(-)(1), SE(3) = 42.0 kcal mol(-)(1)] have been derived from the gas-phase heats of formation and are compared with those from MM3 and PM3 calculations and with the corresponding value SE(1) = 30.1 kcal mol(-)(1) for the parent tricyclo[8.2.2.2(4,7)]hexadeca-1(13),4(16),5,7(15),10(14),11-hexaene (1, [2.2]paracyclophane). The higher strain energies of 2 and 3 (by 4.6 and 11.9 kcal mol(-)(1)) are in accord with the well-known increased reactivities of their aromatic rings as a consequence of their increased bending. As revealed by an X-ray crystal structure analysis, the bending in the monoene 2 corresponds to that of 1 and 3 at one of two bridging corners. PMID:14653746

  14. Protection of HepG2 cells against acrolein toxicity by 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide via glutathione-mediated mechanism.

    PubMed

    Shah, Halley; Speen, Adam M; Saunders, Christina; Brooke, Elizabeth A S; Nallasamy, Palanisamy; Zhu, Hong; Li, Y Robert; Jia, Zhenquan

    2015-10-01

    Acrolein is an environmental toxicant, mainly found in smoke released from incomplete combustion of organic matter. Several studies showed that exposure to acrolein can lead to liver damage. The mechanisms involved in acrolein-induced hepatocellular toxicity, however, are not completely understood. This study examined the cytotoxic mechanisms of acrolein on HepG2 cells. Acrolein at pathophysiological concentrations was shown to cause apoptotic cell death and an increase in levels of protein carbonyl and thiobarbituric acid reactive acid substances. Acrolein also rapidly depleted intracellular glutathione (GSH), GSH-linked glutathione-S-transferases, and aldose reductase, three critical cellular defenses that detoxify reactive aldehydes. Results further showed that depletion of cellular GSH by acrolein preceded the loss of cell viability. To further determine the role of cellular GSH in acrolein-mediated cytotoxicity, buthionine sulfoximine (BSO) was used to inhibit cellular GSH biosynthesis. It was observed that depletion of cellular GSH by BSO led to a marked potentiation of acrolein-mediated cytotoxicity in HepG2 cells. To further assess the contribution of these events to acrolein-induced cytotoxicity, triterpenoid compound 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide (CDDO-Im) was used for induction of GSH. Induction of GSH by CDDO-Im afforded cytoprotection against acrolein toxicity in HepG2 cells. Furthermore, BSO significantly inhibited CDDO-Im-mediated induction in cellular GSH levels and also reversed cytoprotective effects of CDDO-Im in HepG2 cells. These results suggest that GSH is a predominant mechanism underlying acrolein-induced cytotoxicity as well as CDDO-Im-mediated cytoprotection. This study may provide understanding on the molecular action of acrolein which may be important to develop novel strategies for the prevention of acrolein-mediated toxicity. PMID:25504014

  15. HDL derived from the different phases of conjugated diene formation reduces membrane fluidity and contributes to a decrease in free cholesterol efflux from human THP-1 macrophages.

    PubMed

    Girona, Josefa; LaVille, Agnes E; Solà, Rosa; Motta, Claude; Masana, Lluís

    2003-09-22

    Oxidized HDL (ox-HDL) has been reported to reduce free cholesterol efflux from cells. In this study we investigate the effect of different stages of ox-HDL on macrophage membrane fluidity and its effect on free cholesterol efflux from macrophages as a cell function influenced by ox-HDL. HDL was oxidized by means of conjugated diene production using copper as a prooxidant. Fluidity of HDL and human THP-1 macrophage membranes was evaluated by changes in fluorescence anisotropy (r) by DPH probe where lower (r) values give higher fluidity. We found that ox-HDL derived from the propagation phase (PP-HDL) and the decomposition phase (DP-HDL) became less fluid ((r): 0.263+/-0.001, 0.279+/-0.002, respectively) than HDL from the lag phase (LP-HDL) and native HDL (nat-HDL) ((r): 0.206+/-0.001) (P<0.05). Macrophages incubated with PP-HDL and DP-HDL had less fluid membranes ((r): 0.231+/-0.001, 0.243+/-0.002, respectively) than those incubated with LP-HDL and nat-HDL ((r): 0.223+/-0.001) (P<0.05). Consequently, fluidity was reduced not only in ox-HDL but also in the cell membranes exposed to ox-HDL. A significant negative correlation was observed between macrophage membrane fluorescence anisotropy (r) and free cholesterol efflux from these cells (-0.876; P<0.05). Thus, lower membrane fluidity was associated with lower free cholesterol efflux from cells. In conclusion, the increase in the HDL oxidation process leads to a lost of macrophage membrane fluidity that could contribute to an explanation of the reduction of free cholesterol efflux from cells by ox-HDL. PMID:14499733

  16. An ab initio study of relationships between bond lengths and the harmonic and anharmonic cross-coupling constants involving the double bonds in hetero-atom substituted conjugated dienes

    NASA Astrophysics Data System (ADS)

    Bock, Charles W.; Trachtman, Mendel; George, Philip

    1982-12-01

    The lengths of the terminal double bonds and the central CC single bond, and the cross-coupling constant involving the double bonds, calculated ab initio using the unscaled 4-31G basis set, are reported for 15 planar conformers of conjugated dienes containing the OCC'C″ grouping, 9 planar conformers containing the OCC'N grouping, and 6 planar conformers containing the OCC'O'grouping. The larger values for the CC bond length tend to be associated with the smaller values for the double-bond lengths, and vice versa. A linear relationship holds fairly well between rcc and the sum of the double-bond lengths. The sign of the cross-coupling constant is the same for each type of conjugated diene, negative for foc.c'c″ and foc.c'N' but positive for foc.c'o'. The values of foc.c'c″ and f oc.c'N are larger the smaller rcc' in accord with a linear relationship. For all three types of diene the values for pairs of cis and trans conformers do not differ very much, the ratio fcis/ ftrans being a little greater than 1 in ten cases and a little less than 1 in six cases. This lack of any marked difference between cis and trans conformers suggests that the coupling between the double bonds occurs in the main via the bonded framework of the molecule, and that "through-space" interactions, which would be a special feature of cis conformers, are of relatively little importance.

  17. Theoretical Study of Mechanism and Regioselectivity of 1,3-dipolar Cycloaddition of N-[methyl]-C-[5-nitro-2-furyl] Nitrilimine with Dimethyl 7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate

    NASA Astrophysics Data System (ADS)

    Moeinpour, Farid

    2010-04-01

    The mechanism and regioselectivity of 1,3-dipolar cycloaddition of N-[methyl]-C-[5-nitro-2-furyl] nitrilimine with dimethyl 7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate were investigated using activation energy calculations and density functional theory-based reactivity indexes. The reaction proceeds by an asynchronous concerted mechanism. The calculations are performed at the B3LYP/6-31G(d) level of theory and the obtained results are in agreement with experimental outcome.

  18. Eléments traces dans le sérum des enfants malnutris et bien nourris vivants à Lubumbashi et Kawama dans un contexte d'un environnement de pollution minière

    PubMed Central

    Musimwa, Aimée Mudekereza; Kanteng, Gray Wakamb; Kitoko, Hermann Tamubango; Luboya, Oscar Numbi

    2016-01-01

    Introduction La place des éléments traces métalliques essentiels en nutrition humaine ne peut plus être ignorée. Les déficits d'apports, les carences secondaires souvent sous – estimées, et les carences iatrogènes font le lit de pathologies telles que les infections et autres. D'où leurs dosages ont une importance particulière pour en évaluer la gravité et faciliter une prise en charge précoce ou améliorer le régime alimentaire. Cette étude a eu pour objectif de déterminer le profil sanguin en éléments traces (cuivre, sélénium, zinc, fer, chrome, cobalt, etc) chez les enfants malnutris et biens nourris dans un milieu minier à Lubumbashi. Méthodes Trois cents onze cas ont été colligés, 182 malnutris et 129 biens nourris, dans une étude descriptive transversale, effectuée de juillet 2013 à décembre 2014. Pour lequel un échantillonnage exhaustif a été réalisé. Le dosage des métaux dans le sérum s'est fait à l’ ICP-OES (spectrométrie de masse à plasma gon induit) au laboratoire de l'Office Congolais de Contrôle de Lubumbashi. Résultats Les oligoéléments essentiels (cuivre, zinc, sélénium et fer) se retrouvent à des concentrations très basses chez les enfants malnutris comme chez les biens nourris. L'arsenic, le cadmium, le magnésium et le manganèse se présentent à des concentrations normales par rapport aux valeurs de références chez les enfants biens nourris. L'antimoine, le chrome, le plomb et le cobalt se retrouvent élevés chez les malnutris et biens nourris. Le nickel est normal chez les malnutris et les biens nourris. Le magnésium, manganèse se sont présentés à des taux très bas chez les enfants malnutris. Conclusion Les enfants malnutris et biens nourris présentent une malnutrition aux oligo-éléments essentiels associés aux éléments traces métalliques. Ce qui permet de supposer qu'une carence en micronutriments essentiel favorise l'absorption des métaux lourds. PMID:27583075

  19. Structure of trichloro(diethylenetriamine)gold(II), Au(dien)Cl/sub 3/, determined by single-crystal x-ray diffraction, Raman, and EXAFS spectroscopies: an EXAFS caveat

    SciTech Connect

    Elder, R.C.; Watkins, J.W. II

    1986-01-15

    EXAFS spectroscopy of solid samples suggests that Au(dien)Cl/sub 3/ is a molecular entity with pseudooctahedral coordination. The three nitrogen donors from the dien ligand and one chlorine form an equatorial plane with two axial Au-Cl bonds of uncertain length (2.6 or 3.0 A) completing the coordination sphere. A single-crystal X-ray diffraction study confirms the overall structure but yields axial Au-Cl lengths of 3.121 (4) and 3.183 (3) A. The crystals are orthorhombic, space group Pbca, with cell constants a = 12.442 (5), b = 12.878 (9), and c = 13.177 (3) A and eight molecules per unit cell. These molecules were further characterized by Raman spectroscopy in solution as well as the solid state. Equatorial and axial Au-Cl stretching vibrations are observed for both phases, indicating some stability of the Au-Cl(axial) bonds in solution. 25 references, 3 figures, 4 tables.

  20. Crystal structure of 4,4-di­bromo-1-(3,4-di­meth­oxy­phen­yl)-2-aza­buta-1,3-diene-1-carbo­nitrile

    PubMed Central

    Chaabene, Marwa; Khatyr, Abderrahim; Knorr, Michael; Askri, Moheddine; Rousselin, Yoann; Kubicki, Marek M.

    2016-01-01

    The title compound, C12H10Br2N2O2, represents an example of a planar π-con­jugated 2-aza­butadiene mol­ecule, which is both an inter­esting starting material for further organic transformations and a potential ligand in organometallic coordination chemistry. Its metric mol­ecular parameters are typical for the family of 2-aza­buta-1,3-dienes not substituted at the (CH) 3-position. In the crystal, the almost planar (r.m.s. deviation = 0.0658 Å) aza­diene mol­ecules form one-dimensional double-wide ribbons through inter­molecular halogen bonds (C—Br⋯O and C—Br⋯Br—C), which then stack in a slipped manner through weak C—H⋯Br and π–π inter­actions to generate a three-dimensional network. PMID:27536405

  1. ([2.2.2]Cryptand-κ6 O)potassium (η4-cyclo­octa­diene)bis­(η2-pyrene)cobaltate(1−) pentane hemisolvate

    PubMed Central

    Brennessel, William W.; Ellis, John E.

    2012-01-01

    The cation, anion, and solvent in the title compound, [K(C18H36N2O6)][Co(C8H12)(C16H10)2]·0.5C5H12, are well separated. The pentane solvent mol­ecules are found in channels along [100] and were modeled as disordered over crystallographic inversion centers. Using the mid-points of the coordinated olefins, the angle between the Cpy/Cpy–Co–Cpy/Cpy and the Ccod/Ccod–Co–Ccod/Ccod planes (py is pyrene and cod is cyclo­octa­diene) is 67.6 (2)°. Thus, the overall geometry of the coordination sphere around cobalt is best described as distorted tetra­hedral. PMID:22807709

  2. (18-Crown-6)potassium [(1,2,5,6-η)-cyclo­octa-1,5-diene][(1,2,3,4-η)-naph­tha­lene]­ferrate(−I)

    PubMed Central

    Brennessel, William W.; Ellis, John E.

    2012-01-01

    The title salt, [K(C12H24O6)][Fe(C8H12)(C10H8)], is the only known naphthalene complex containing iron in a formally negative oxidation state. Each (naphthalene)(1,5-cod)ferrate(−I) anion is in contact with one (18-crown-6)potassium cation via K⋯C contacts to the outer four carbon atoms of the naphthalene ligand (cod = 1,5-cyclo­octa­diene, 18-crown-6 = 1,4,7,10,13,16-hexa­oxacyclo­octa­deca­ne). When using the midpoints of the coordinating olefin bonds, the overall geometry of the coordination sphere around iron can be best described as distorted tetra­hedral. The naphthalene fold angle between the plane of the iron-coordinating butadiene unit and the plane containing the exo-benzene moiety is 19.2 (1)°. PMID:23125569

  3. Identification of (3S, 9R)- and (3S, 9S)-megastigma-6,7-dien-3,5,9-triol 9-O-beta-D-glucopyranosides as damascenone progenitors in the flowers of Rosa damascena Mill.

    PubMed

    Suzuki, Masayuki; Matsumoto, Shigetaka; Mizoguchi, Masaya; Hirata, Satoshi; Takagi, Kazuteru; Hashimoto, Ikue; Yamano, Yumiko; Ito, Masayoshi; Fleischmann, Peter; Winterhalter, Peter; Morita, Tetuichiro; Watanabe, Naoharu

    2002-12-01

    The progenitors of damascenone (1), the most intensive C13-norisoprenoid volatile aroma constituent of rose essential oil, were surveyed in the flowers of Rosa damascena Mill. Besides 9-O-beta-D-glucopyranosyl-3-hydroxy-7,8-didehydro-beta-ionol (4b), a stable progenitor already isolated from the residual water after steam distillation of flowers of R. damascena Mill., two labile progenitors were identified to be (3S, 9R)- and (3S, 9S)-megastigma-6,7-dien-3,5,9-triol 9-O-beta-D-glucopyranosides (2b) based on their synthesis and HPLC-MS analytical data. Compound 2b gave damascenone (1), 3-hydroxy-beta-damascone (3) and 4b upon heating under acidic conditions. PMID:12596869

  4. [4+2] cycloaddition reactions between 1,8-disubstituted cyclooctatetraenes and diazo dienophiles: stereoelectronic effects, anticancer properties and application to the synthesis of 7,8-substituted bicyclo[4.2.0]octa-2,4-dienes.

    PubMed

    Grange, Rebecca L; Gallen, Michael J; Schill, Heiko; Johns, Jenny P; Dong, Lin; Parsons, Peter G; Reddell, Paul W; Gordon, Victoria A; Bernhardt, Paul V; Williams, Craig M

    2010-08-01

    A detailed examination of [4+2] cycloaddition reactions between 1,8-disubstituted cyclooctatetraenes and diazo compounds revealed that 4-phenyl-1,2,4-triazole-3,5-dione (PTAD) reacts to form either 2,3- or 3,4-disubstituted adducts. The product distribution can be controlled by modulating the electron density of the cyclooctatetraene. Unprecedented [4+2] cycloadditions between diisopropyl azodicarboxylate (DIAD) and 1,8-disubstituted cyclooctatetraenes are also described and further manipulation of a resulting cycloadduct uncovered a new pathway to the synthetically challenging bicyclo[4.2.0]octa-2,4-diene family. Variation of the substituents resulted in a range of compounds displaying selective action against different human tumour cell types. PMID:20572168

  5. Crystal structure of dimethyl 3,4,5,6-tetra­phenyl­cyclo­hexa-3,5-diene-1,2-di­carboxyl­ate

    PubMed Central

    Greenberg, Fred H.; Nazarenko, Alexander Y.

    2016-01-01

    In the title compound, C34H28O4, the cyclo­hexa­diene ring has a screw-boat conformation with a torsion angle between the double bonds being on average ca 15° [15.2 (3) and −15.3 (3) in the two independent mol­ecules]. All four phenyl rings in both mol­ecules are arranged in a propeller-like conformation. The two mol­ecules exhibit S,R- and R,S- chirality, respectively, and are connected via C—H⋯O inter­molecular inter­actions. In turn, these weakly bound dimers form the mol­ecular crystal. PMID:27555937

  6. High-Pressure Micellar Solutions of Symmetric and Asymmetric Styrene?Diene Diblocks in Compressible Near Critical Solvents: Micellization Pressures and Cloud Pressures Respond but Micellar Cloud Pressures Insensitive to Copolymer Molecular Weight, Concentration, and Block Ratio Changes

    SciTech Connect

    Winoto, Winoto; Tan, Sugata; Shen, Youqin; Radosz, Maciej; Hong, Kunlun; Mays, Jimmy

    2009-01-01

    Micellar solutions of polystyrene-block-polybutadiene and polystyrene-block-polyisoprene in propane are found to exhibit significantly lower cloud pressures than the corresponding hypothetical nonmicellar solutions. Such a cloud-pressure reduction indicates the extent to which micelle formation enhances the apparent diblock solubility in near-critical and hence compressible propane. Concentration-dependent pressure-temperature points beyond which no micelles can be formed, referred to as the micellization end points, are found to depend on the block type, size, and ratio. The cloud-pressure reduction and the micellization end point measured for styrene-diene diblocks in propane should be characteristic of all amphiphilic diblock copolymer solutions that form micelles in compressible solvents.

  7. Reactions of 7,8-dithiabicyclo[4.2.1]nona-2,4-diene 7-exo-oxide with dodecacarbonyl triiron Fe3(CO)12: a novel type of sulfenato thiolato diiron hexacarbonyl complexes.

    PubMed

    Windhager, Jochen; Apfel, Ulf-Peter; Yoshino, Tomoharu; Nakata, Norio; Görls, Helmar; Rudolph, Manfred; Ishii, Akihiko; Weigand, Wolfgang

    2010-07-01

    The reaction of Fe(3)(CO)(12) (13) with 7,8-dithiabicyclo[4.2.1]nona-2,4-diene 7-exo-oxide (12) yields the sulfenato-thiolato complex 14, which is used as starting material for further reactions. The disulfenato complex 17 is obtained by using one equivalent of dimethyldioxirane (DMD), and the monoepoxide 18 is prepared by the oxidation of 14 with an excess of DMD. Complex 14 can be converted to the monophosphine complexes 19a and 19b by subsequent substitution of one CO ligand using trimethylaminoxide Me(3)NO and triphenylphosphine PPh(3). Additional substitution reactions are done with 17 by using acetonitrile as a ligand to form 20a and 20b. In the electrochemical part of the paper, the reactions of the reduced iron species 14, 15, 17, and 19a are studied. PMID:20473980

  8. Analysis of the aliphatic monomer composition of polyesters associated with Arabidopsis epidermis: occurrence of octadeca-cis-6, cis-9-diene-1,18-dioate as the major component.

    PubMed

    Bonaventure, Gustavo; Beisson, Frédéric; Ohlrogge, John; Pollard, Mike

    2004-12-01

    Although the surface waxes from Arabidopsis thaliana leaves and stems have been thoroughly characterized, the monomer composition of the polyesters of the cuticular membrane has not been analyzed. Delipidated Arabidopsis leaves or stems, when depolymerized under conditions to cleave polyesters, produced typical omega-hydroxy fatty acid cutin monomers such as 16-hydroxy-palmitate, 10,16-dihydroxy-palmitate and 18-hydroxy-9,10-epoxy-stearate. However, the major monomer was octadeca-cis-6, cis-9-diene-1,18-dioate, with lesser amounts of octadec-cis-9-ene-1,18-dioate and hexadeca-1,16-dioate. These dicarboxylates were found predominantly in epidermal peels from Arabidopsis stems and are therefore likely to be associated with the cuticular membrane. They were also found in analyses of canola leaves but were absent in tomato and apple fruit cutins. In the fad2-1 mutant line of Arabidopsis, which has reduced levels of linoleate and linolenate and elevated oleate in cytosolic phospholipids, the amount of octadeca-cis-6, cis-9-diene-1,18-dioate was 50% reduced, with a concomitant increase in octadec-cis-9-ene-1,18-dioate. In a fatb-ko line of Arabidopsis, where the availability of cytosolic palmitate is impaired, there was an 80% loss of C16 monomers and a compensating increase in C18 monomers. The presence of substantial amounts of dicarboxylates in cuticular membranes is unexpected. High amounts of aliphatic dicarboxylates are usually considered as an indicator of suberin, and are reported only as very minor components of cutin. The high level of polyunsaturation is also unusual in cuticles; saturated fatty acid monomers usually predominate, with lesser amounts of monounsaturates. These novel findings for Arabidopsis demonstrate that a broad range of monomer compositions are possible for polyesters of the epidermis. PMID:15584957

  9. Crystal structure of μ-fluorido-bis-{(η(4)-cyclo-octa-diene)[hexa-fluorido-anti-monato(V)]platinum(II)} hexa-fluorido-anti-monate(V) hydrogen fluoride 0.75-solvate.

    PubMed

    Seppelt, Konrad; Friedemann, Roland

    2016-01-01

    In the complex cation of the binuclear solvated title salt, [Pt2F(SbF6)2(C8H12)2]SbF6·0.75HF, an F atom bridges the two platinum(II) atoms with a bond angle of 123.3 (2)°. The corresponding Pt-F bond lengths are in the range of other fluorine-bridged binuclear platinum(II) complexes. Two of the three SbF6 (-) anions each coordinate with one F atom to one platinum(II) atom. Including the η(4)-bound cyclo-octa-diene (COD) ligands, the overall coordination sphere of each platinum(II) atom is square-planar. The third SbF6 (-) anion is not bound to the complex. Hydrogen fluoride is present in the crystal structure as a solvent disordered over three positions, each with an occupancy of 0.25. F⋯F distances of 2.5512 (7), 2.6076 (8) and 3.2215 (10) Å to surrounding SbF6 (-) anions are indicative of F-H⋯F hydrogen-bonding inter-actions although no H atoms could be localized for the disordered solvent mol-ecules. The resulting hydrogen-bonded network is three-dimensional. PMID:26870575

  10. The antidiabetic compound 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione, isolated from averrhoa carambola L., demonstrates significant antitumor potential against human breast cancer cells

    PubMed Central

    Gao, Ying; Huang, Renbin; Gong, Yixuan; Park, Hyo Sim; Wen, Qingwei; Almosnid, Nadin Marwan; Chippada-Venkata, Uma D.; Hosain, Najlaa Abdulrhman; Vick, Eric; Farone, Anthony; Altman, Elliot

    2015-01-01

    2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) is a cyclohexanedione found in the roots of Averrhoa carambola L., commonly known as starfruit. Researchers have shown that DMDD has significant therapeutic potential for the treatment of diabetes; however, the effects of DMDD on human cancers have never been reported. We investigated the cytotoxic effects of DMDD against human breast, lung and bone cancer cells in vitro and further examined the molecular mechanisms of DMDD-induced apoptosis in human breast cancer cells. DMDD suppressed the growth of breast carcinoma cells, but not normal mammary epithelial cells, via induction of G1 phase cell cycle arrest, oxidative stress and apoptosis. DMDD increased the level of intracellular reactive oxygen species (ROS) and DMDD-induced ROS generation was found to be associated with the mitochondrial activity. The cytotoxicity that was induced by DMDD was attenuated by co-treatment with the antioxidant N-acetyl-L-cysteine (NAC). DMDD-induced cell apoptosis involved the activation of both the intrinsic mitochondrial pathway and the extrinsic receptor pathway. In addition, DMDD inhibited the canonical NF-κB signaling pathway at all steps, including TNF-α production, phosphorylation of NF-κB p65 and IκBα, as well as TNF-α activated NF-κB p65 nuclear translocation. Collectively, our studies indicate that DMDD has significant potential as a safe and efficient therapeutic agent for the treatment of breast cancer. PMID:26203774

  11. Synthesis of novel 17-(4'-formyl)pyrazolylandrosta-5,16-dienes and their derivatives as potent 17α-hydroxylase/C17,20-lyase inhibitors or antiproliferative agents depending on the substitution pattern of the heteroring.

    PubMed

    Kovács, Dóra; Wölfling, János; Szabó, Nikoletta; Szécsi, Mihály; Schelz, Zsuzsanna; Zupkó, István; Frank, Éva

    2016-09-14

    A series of novel 17-(4'-formyl)pyrazolylandrosta-5,16-dienes were efficiently synthesized in two steps from pregnadienolone acetate with monosubstituted hydrazines via the cyclization/formylation sequence of the primarily formed hydrazones on treatment with the Vilsmeier-Haack reagent. The products were further transformed by deacetylation and subsequent reduction in order to enlarge the compound library available for pharmacological studies. Moreover, 4'-formylpyrazoles containing H or Me on the heteroring-N were subjected to oxime formation and Ac2O-induced dehydration to furnish the corresponding 4'-cyano derivatives in good yields. The antiproliferative activities of the structurally related steroidal 17-exo-pyrazole derivatives were tested in vitro on four human adherent breast cancer cell lines (MCF7, T47D, MDA-MB-231 and MDA-MB-361): the microculture tetrazolium assay revealed that seven compounds exerted better cell growth-inhibitory effects on some or all these cell lines than those of the reference cisplatin. With regard to the well-known structural features that a potent C17,20-lyase inhibitor should possess, some relevant derivatives were tested in vitro from the aspects of their inhibitory effects on rat testicular enzyme, and one of them proved to exert noteworthy enzyme-inhibitory action, with an IC50 (26 nM) of the same order of magnitude as that of abiraterone. PMID:27209562

  12. Therapeutic effects of C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me; bardoxolone methyl) on radiation-induced lung inflammation and fibrosis in mice

    PubMed Central

    Wang, Yan-Yang; Zhang, Cui-Ying; Ma, Ya-Qiong; He, Zhi-Xu; Zhe, Hong; Zhou, Shu-Feng

    2015-01-01

    The C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me), one of the synthetic triterpenoids, has been found to have potent anti-inflammatory and anticancer properties in vitro and in vivo. However, its usefulness in mitigating radiation-induced lung injury (RILI), including radiation-induced lung inflammation and fibrosis, has not been tested. The aim of this study was to explore the therapeutic effect of CDDO-Me on RILI in mice and the underlying mechanisms. Herein, we found that administration of CDDO-Me improved the histopathological score, reduced the number of inflammatory cells and concentrations of total protein in bronchoalveolar lavage fluid, suppressed secretion and expression of proinflammatory cytokines, including transforming growth factor-β and interleukin-6, elevated expression of the anti-inflammatory cytokine interleukin-10, and downregulated the mRNA level of profibrotic genes, including for fibronectin, α-smooth muscle actin, and collagen I. CDDO-Me attenuated radiation-induced lung inflammation. CDDO-Me also decreased the Masson’s trichrome stain score, hydroxyproline content, and mRNA level of profibrotic genes, and blocked radiation-induced collagen accumulation and fibrosis. Collectively, these findings suggest that CDDO-Me ameliorates radiation-induced lung inflammation and fibrosis, and this synthetic triterpenoid is a promising novel therapeutic agent for RILI. Further mechanistic, efficacy, and safety studies are warranted to elucidate the role of CDDO-Me in the management of RILI. PMID:26124639

  13. DNA incision evaluation, binding investigation and biocidal screening of novel metallonucleases of 1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione based Knoevenagel condensate having methionine: Synthesis and structural validation

    NASA Astrophysics Data System (ADS)

    Chandrasekar, Thiravidamani; Pravin, Narayanaperumal; Raman, Natarajan

    2015-02-01

    Four new metallonucleases of the composition [MLCl] (where M = Cu(II), Ni(II), Zn(II) and Co(II); L = Knoevenagel condensate Schiff base, obtained by the condensation reaction of 1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione with p-nitrobenzaldehyde and methionine amino acid) have been synthesised and characterized thoroughly by microanalytical data, magnetic susceptibility, molar conductivity, UV-Vis., IR, 1H NMR, 13C NMR and EPR spectral techniques. Their geometry is investigated and established to have square planar geometry. Electronic absorption spectroscopy, cyclic voltammetry and viscosity measurements reveal that the complexes strongly bind to calf thymus DNA via an intercalation mechanism. DNA cleavage efficiency of these complexes is explored by gel electrophoresis, and they are found to endorse the cleavage of pBR322 DNA in presence of oxidant H2O2. These results reveal that all the complexes show better nuclease activity. Moreover, the biological screening against few pathogens reveals that that the complexes have potent biocidal activity than the free ligand.

  14. A comparison between the effects of gamma radiation and sulfur cure system on the microstructure and crosslink network of (styrene butadiene rubber/ethylene propylene diene monomer) blends in presence of nanoclay

    NASA Astrophysics Data System (ADS)

    Shoushtari Zadeh Naseri, Aida; Jalali-Arani, Azam

    2015-10-01

    Rubber blends based on (styrene-butadiene rubber (SBR)/ethylene-propylene-diene monomer (EPDM)) with and without organoclay (OC) were prepared through a melt mixing process. The concentration ratio of the rubber phases (EPDM/SBR; 50/50 wt%) and the amount of the OC were kept constant. The samples were then vulcanized by means of gamma radiation using a Co-60 gamma source as well as sulfur cure system. The effect of absorbed dose on the formation of the crosslinks was confirmed by the Fourier transform infrared spectroscopy (FTIR). The effects of absorbed dose, sulfur cure system and OC on the gel content, and crosslink density were evaluated by the chemical tests. Applying the Charlesby-Pinner equation to estimate the radiation chemical yield, revealed that the use of OC in the blend caused 20% reduction in the degradation/crosslinking ratio. Employing the swelling test data, some thermodynamic parameters were determined. Using field emission scanning electron microscopy (FE-SEM) to investigate microstructure of the samples revealed a more homogeneous structure and also an increase in compatibility of the blend components in the sample cured by the irradiation in comparison to that cured by the sulfur curing system.

  15. The antidiabetic compound 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione, isolated from Averrhoa carambola L., demonstrates significant antitumor potential against human breast cancer cells.

    PubMed

    Gao, Ying; Huang, Renbin; Gong, Yixuan; Park, Hyo Sim; Wen, Qingwei; Almosnid, Nadin Marwan; Chippada-Venkata, Uma D; Hosain, Najlaa Abdulrhman; Vick, Eric; Farone, Anthony; Altman, Elliot

    2015-09-15

    2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) is a cyclohexanedione found in the roots of Averrhoa carambola L., commonly known as starfruit. Researchers have shown that DMDD has significant therapeutic potential for the treatment of diabetes; however, the effects of DMDD on human cancers have never been reported. We investigated the cytotoxic effects of DMDD against human breast, lung and bone cancer cells in vitro and further examined the molecular mechanisms of DMDD-induced apoptosis in human breast cancer cells. DMDD suppressed the growth of breast carcinoma cells, but not normal mammary epithelial cells, via induction of G1 phase cell cycle arrest, oxidative stress and apoptosis. DMDD increased the level of intracellular reactive oxygen species (ROS) and DMDD-induced ROS generation was found to be associated with the mitochondrial activity. The cytotoxicity that was induced by DMDD was attenuated by co-treatment with the antioxidant N-acetyl-L-cysteine (NAC). DMDD-induced cell apoptosis involved the activation of both the intrinsic mitochondrial pathway and the extrinsic receptor pathway. In addition, DMDD inhibited the canonical NF-κB signaling pathway at all steps, including TNF-α production, phosphorylation of NF-κB p65 and IκBα, as well as TNF-α activated NF-κB p65 nuclear translocation.Collectively, our studies indicate that DMDD has significant potential as a safe and efficient therapeutic agent for the treatment of breast cancer. PMID:26203774

  16. A mutant form of 3-ketosteroid-Δ(1)-dehydrogenase gives altered androst-1,4-diene-3, 17-dione/androst-4-ene-3,17-dione molar ratios in steroid biotransformations by Mycobacterium neoaurum ST-095.

    PubMed

    Shao, Minglong; Zhang, Xian; Rao, Zhiming; Xu, Meijuan; Yang, Taowei; Li, Hui; Xu, Zhenghong; Yang, Shangtian

    2016-05-01

    Mycobacterium neoaurum ST-095 and its mutant M. neoaurum JC-12, capable of transforming phytosterol to androst-1,4-diene-3,17-dione (ADD) and androst-4-ene-3,17-dione (AD), produce very different molar ratios of ADD/AD. The distinct differences were related to the enzyme activity of 3-ketosteroid-Δ(1)-dehydrogenase (KSDD), which catalyzes the C1,2 dehydrogenation of AD to ADD specifically. In this study, by analyzing the primary structure of KSDDI (from M. neoaurum ST-095) and KSDDII (from M. neoaurum JC-12), we found the only difference between KSDDI and KSDDII was the mutation of Val(366) to Ser(366). This mutation directly affected KSDD enzyme activity, and this result was confirmed by heterologous expression of these two enzymes in Bacillus subtilis. Assay of the purified recombinant enzymes showed that KSDDII has a higher C1,2 dehydrogenation activity than KSDDI. The functional difference between KSDDI and KSDDII in phytosterol biotransformation was revealed by gene disruption and complementation. Phytosterol transformation results demonstrated that ksdd I and ksdd II gene disrupted strains showed similar ADD/AD molar ratios, while the ADD/AD molar ratios of the ksdd I and ksdd II complemented strains were restored to their original levels. These results proved that the different ADD/AD molar ratios of these two M. neoaurum strains were due to the differences in KSDD. Finally, KSDD structure analysis revealed that the Val(366)Ser mutation could possibly play an important role in stabilizing the active center and enhancing the interaction of AD and KSDD. This study provides a reliable theoretical basis for understanding the structure and catalytic mechanism of the Mycobacteria KSDD enzyme. PMID:26886757

  17. Methyl 2-Cyano-3,11-dioxo-18-olean-1,12-dien-30-oate (CDODA-Me), a Derivative of Glycyrrhetinic Acid, Functions as a Potent Angiogenesis Inhibitor

    PubMed Central

    Pang, Xiufeng; Zhang, Li; Wu, Yougen; Lin, Lei; Li, Jingjie; Qu, Weijing; Safe, Stephen

    2010-01-01

    Methyl 2-cyano-3,11-dioxo-18-olean-1,12-dien-30-oate (CDODA-Me), a triterpenoid acid derived synthetically from glycyrrhetinic acid, has been characterized as a peroxisome proliferator-activated receptor γ agonist with a broad range of receptor-dependent and -independent anticancer activities. Although CDODA-Me decreases the expression of some angiogenic genes in cancer cells, the direct effects of this compound on angiogenesis have not been defined. In this study, we have extensively investigated the activities of CDODA-Me in multiple angiogenesis assays. Our results showed that this agent inhibited vascular endothelial growth factor (VEGF)-induced proliferation, migration, invasion, and lamellipodium and capillary-like structure formation of human umbilical endothelial cells (HUVECs) in a concentration-dependent manner. Moreover, CDODA-Me abrogated VEGF-induced sprouting of microvessels from rat aortic rings ex vivo and inhibited the generation of new vasculature in the Matrigel plugs in vivo, where CDODA-Me significantly decreased the number of infiltrating von Willebrand factor-positive endothelial cells. To understand the molecular basis of this antiangiogenic activity, we examined the signaling pathways in CDODA-Me-treated HUVECs. Our results showed that CDODA-Me significantly suppressed the activation of VEGF receptor 2 (VEGFR2) and interfered with the mammalian target of rapamycin (mTOR) signaling, including mTOR kinase and its downstream ribosomal S6 kinase (S6K), but had little effect on the activities of extracellular signal-regulated protein kinase and AKT. Taken together, CDODA-Me blocks several key steps of angiogenesis by inhibiting VEGF/VEGFR2 and mTOR/S6K signaling pathways, making the compound a promising agent for the treatment of cancer and angiogenesis-related pathologies. PMID:20631299

  18. Crystal structure of (18-crown-6)potassium(I) [(1,2,3,4,5-η)-cyclo­hepta­dien­yl][(1,2,3-η)-cyclo­hepta­trien­yl]cobalt(I)

    PubMed Central

    Brennessel, William W.; Ellis, John E.

    2015-01-01

    The reaction of bis­(anthracene)cobaltate(−I) with excess cyclo­hepta­triene, C7H8, resulted in a new 18-electron cobaltate containing two different seven-membered ring ligands, based on single-crystal X-ray diffraction. The asymmetric unit of this structure contains two independent cation–anion pairs of the title complex, [K(18-crown-6)][Co(η3-C7H7)(η5-C7H9)], where 18-crown-6 stands for 1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane (C12H24O6), in general positions and well separated. Each (18-crown-6)potassium cation is in contact with the η3-coordinating ligand of one cobaltate complex. Each η3-coordinating ligand behaves as an allylic anion whose exo-diene moiety is bent away from the allylic plane, and thus is not involved directly in the bonding. The metal-coordinating portions of the anionic η5 ligands are planar and one of these ligands is modeled as disordered over two positions, with occupancy ratio 0.699 (5):0.301 (5), such that one orientation is rotated by one carbon atom with respect to the other. The diffraction intensities were integrated according to non-merohedral twin law [-1 0 0/0 -1 0/0.064 0 1], a 180° rotation about reciprocal lattice axis [001], and the masses of the twin domains refined to equal amounts. As both ligands are formally coordinated as anions, the cobalt atom is best considered to be CoI. This compound is of inter­est as the first to possess cyclo­hepta­trienyl and cyclo­hepta­dienyl ligands in an anionic metal complex. PMID:25844191

  19. In Vitro Activity of 2-methoxy-1,4-naphthoquinone and Stigmasta-7,22-diene-3β-ol from Impatiens balsamina L. against Multiple Antibiotic-Resistant Helicobacter pylori

    PubMed Central

    Wang, Yuan-Chuen; Li, Wan-Yu; Wu, Deng-Chyang; Wang, Jeh-Jeng; Wu, Cheng-Hsun; Liao, Jyun-Ji; Lin, Cheng-Kun

    2011-01-01

    Infection with Helicobacter pylori is strongly associated with gastric cancer and gastric adenocarcinoma. WHO classified H. pylori as a group 1 carcinogen in 1994. Impatiens balsamina L. has been used as indigenous medicine in Asia for the treatment of rheumatism, fractures and fingernail inflammation. In this study, we isolated anti-H. pylori compounds from this plant and investigated their anti- and bactericidal activity. Compounds of 2-methoxy-1,4-naphthoquinone (MeONQ) and stigmasta-7,22-diene-3β-ol (spinasterol) were isolated from the pods and roots/stems/leaves of I. balsamina L., respectively. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) for MeONQ were in the ranges of 0.156–0.625 and 0.313–0.625 μg mL−1, respectively, and in the ranges of 20–80 μg mL−1 both of MICs and MBCs for spinasterol against antibiotic (clarithromycin, metronidazole and levofloxacin) resistant H. pylori. Notably, the activity of MeONQ was equivalent to that of amoxicillin (AMX). The bactericidal H. pylori action of MeONQ was dose-dependent. Furthermore, the activity of MeONQ was not influenced by the environmental pH values (4–8) and demonstrated good thermal (121°C for 15 min) stability. MeONQ abounds in the I. balsamina L. pod at the level of 4.39% (w/w db). In conclusion, MeONQ exhibits strong potential to be developed as a candidate agent for the eradication of H. pylori infection. PMID:19773391

  20. A focal adhesion kinase inhibitor 16-hydroxy-cleroda-3,13-dien-16,15-olide incorporated into enteric-coated nanoparticles for controlled anti-glioma drug delivery.

    PubMed

    Thiyagarajan, Varadharajan; Lin, Shi-Xiang; Lee, Chia-Hung; Weng, Ching-Feng

    2016-05-01

    16-Hydroxy-cleroda-3,13-dien-16,15-olide (HCD) which is extracted from a medicinal plant, Polyalthia longifolia, was shown to exhibit anticancer activity through apoptosis and FAK inhibition in our previous study. To improve its solubility and efficacy, a novel HCD delivery system using copper-substituted mesoporous silica nanoparticles (MSNs) was designed as a delivery vehicle, and the outer surfaces of MSNs were further coated with enteric polymers to prevent the drug from leaching in the stomach acid. All the data regarding synthesis and physical characterization, including Zeta potential, FT-IR spectra, N2 adsorption-desorption isotherms (BET), drug loading, powder X-ray diffraction, Thermo gravimetric analysis (TGA), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM) were well characterized. The non-coated MSN-HCD exposed to acidic pH (1.2) showed a rapid degradation of the drug, whereas the enteric-coated samples presented a sustained release profile in the gastrointestinal pHs. Cell cytotoxicity was further confirmed by the MTT-C6 Glioma cell line, in vitro. When compared with the control and pure HCD, the MSN-HCD revealed a potential anti-proliferation effect via the synergistic effect of the drug and the MSN vehicle. Additionally, this MSN-HCD had the effect of increasing the reactive oxygen species (ROS) levels and altered the Mitochondria membrane potential (MMP) in C6 cell line. The in vivo anti-tumor efficacy of enteric-coated MSN-HCD was evaluated by C6 Glioma bearing xenograft nude mice, and enteric-coated MSN-HCD clearly exhibited the greatest anti-glioma activity, as compared to the pure HCD and the untreated control. In terms of the effective treatment of brain glioma, this study provides conclusive evidence of the successful development of the anti-cancer agent HCD conjugated with enteric-coated MSN as a delivery control mechanism with enhanced dissolution characteristics. PMID:26851441

  1. 2-Cyano-3,12-dioxoolean-1,9-dien-28-oic acid and related compounds inhibit growth of colon cancer cells through peroxisome proliferator-activated receptor gamma-dependent and -independent pathways.

    PubMed

    Chintharlapalli, Sudhakar; Papineni, Sabitha; Konopleva, Marina; Andreef, Michael; Samudio, Ismael; Safe, Stephen

    2005-07-01

    2-Cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and the corresponding methyl (CDDO-Me) and imidazole (CDDO-Im) esters induce peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent transactivation in SW-480 colon cancer cells, and these responses were inhibited by small inhibitory RNA for PPARgamma. Moreover, in a mammalian two-hybrid assay using the PPARgamma(2)-VP16 fusion plasmid and GAL4-coactivator/corepressor chimeras and a construct (pGAL4) containing five tandem GAL4 response elements, CDDO, CDDO-Me, and CDDO-IM induce transactivation and PPARgamma interaction with multiple coactivators. A major difference among the three PPARgamma agonists was the higher activity of CDDO-Im to induce PPARgamma interactions with the corepressor SMRT. CDDO, CDDO-Me, and CDDO-Im inhibited SW-480, HCT-116, and HT-29 colon cancer cell proliferation at low concentrations and induced cell death at higher concentrations. Growth inhibition at lower concentrations correlated with induction of the tumor suppressor gene caveolin-1 which is known to inhibit colon cancer cell growth. Induction of caveolin-1 by CDDO, CDDO-Me, and CDDO-Im was inhibited by the PPARgamma antagonist N-(4'-aminopyridyl-2-chloro-5-nitrobenzamide (T007), whereas higher doses induced apoptosis [poly(ADP-ribose) polymerase cleavage], which was not inhibited by T007. These results illustrate that CDDO-, CDDO-Me, and CDDO-Im induce both PPARgamma-dependent and -independent responses in colon cancer cells, and activation of these pathways are separable and concentration-dependent for all three compounds. PMID:15798084

  2. Ultraviolet photochemistry of Co{sup III}L(H{sub 2}O)SO{sub 3}{sup +} [L = Me{sub 6}[14]dieneN{sub 4}, [14]aneN{sub 4}] complexes. Quandaries about the linkage isomerization to O-bonded sulfite and the photogeneration of cobalt(I) in sequential biphotonic photolysis

    SciTech Connect

    Gibney, S.C.; Ferraudi, G.; Shang, M.

    1999-06-14

    The catalyzed and uncatalyzed oxidation of sulfite have been a matter of continued interest. Attention to these processes has a basic science motive as well as the need to resolve a number of long-recognized technical problems, i.e., gas desulfurization, pollution, and health problems. Two new macrocyclic complexes with S-bonded sulfite, Co(Me{sub 6}[14]diene N{sub 4})(H{sub 2}O)SO{sub 3}{sup +} and Co([14]ane N{sub 4})(H{sub 2}O)SO{sub 3}{sup +}, were prepared. The type of the So{sub 3}{sup 2{minus}} linkage in [Co(Me{sub 6}[14]diene N{sub 4})(H{sub 2}O)SO{sub 3}]ClO{sub 4} was established by means of the X-ray structure (crystal system, orthorhombic). In a study of the photochemical properties, transient spectra revealed the photoredox formation of Co(II) macrocycles and the photoisomerization to O-bonded sulfite. Precursors of these products were also observed and tentatively identified as an ion pair and an adduct of the SO{sub 3}{sup {sm_bullet}{minus}} radical and the unsaturated macrocycle Me{sub 6}[14]diene N{sub 4}. The photogeneration of SO{sub 3}{sup {sm_bullet}{minus}} was verified by means of the radical`s ESR spectrum. High power laser irradiations resulted in the secondary photolysis of the intermediates and the formation of Co(I) products. The mechanism of the primary and secondary photolysis is discussed.

  3. (2R*,4R*,7S*,10R*,12R*)-3,11,13,15-Tetra­oxa­penta­cyclo­[5.5.3.01,7.02,4.010,12]penta­deca-5,8-dien-14-one

    PubMed Central

    Mehta, Goverdhan; Sen, Saikat; Kumar, C. S. Ananda

    2013-01-01

    The title compound, C11H8O5, features a ‘skipped’ diene, an anti-bis­(epoxide) and a cyclic carbonate, all embedded in a densely functionalized [4.4.3]propellane scaffold. The crystal packing of this diepoxide is effected primarily by C—H⋯O hydrogen bonds, which link the mol­ecules into tapes along the b axis. Inter-tape connectivity is brought about by centrosymmetrically disposed pairs of C⋯O contacts [3.183 (4) Å] between the Cδ+=Oδ- dipoles of neighbouring carbonate moieties. PMID:24098200

  4. Clinical association of baseline levels of conjugated dienes in low-density lipoprotein and nitric oxide with aggressive B-cell non-Hodgkin lymphoma and their relationship with immunoglobulins and Th1-to-Th2 ratio

    PubMed Central

    Haddouche, Mustapha; Meziane, Warda; Hadjidj, Zeyneb; Mesli, Naima; Aribi, Mourad

    2016-01-01

    Objective The aim of this study was to highlight the clinical association of baseline levels of conjugated dienes in low-density lipoprotein (LDL-BCD) and nitric oxide (NO) with immunoglobulins (Igs) and T helper (Th)1/Th2 ratio in patients with newly diagnosed B-cell non-Hodgkin lymphoma (NHL). Patients and methods Thirty-two newly diagnosed patients with aggressive B-cell NHL and 25 age-, sex-, and body-mass-index-matched healthy controls were randomly selected for a cross-sectional case–control study conducted at the Hematology Department of Tlemcen Medical Centre University (northwest of Algeria). Results Circulating levels of LDL-BCD and NO and those of IgA and IgM were significantly higher in patients than in controls. The levels of Th1/Th2 ratio and plasma total antioxidant capacity were significantly lower in patients compared with controls, while malondialdehyde and protein carbonyl levels were significantly higher in patients. B-cell NHL was significantly associated with high levels of LDL-BCD from 25th to 75th percentile (25th percentile: relative risk [RR] =2.26, 95% confidence interval [CI] 1.42–3.59, P=0.014; 50th percentile: RR =2.84, 95% CI 1.72–4.68, P<0.001; 75th percentile: RR =5.43, 95% CI 2.58–11.42, P<0.001). Similarly, the disease was significantly associated with high levels of NO production from 25th to 75th percentile (25th percentile: RR =2.07, 95% CI 1.25–3.44, P=0.024; 50th percentile: RR =2.78, 95% CI 1.63–4.72, P<0.001; 75th percentile: RR =4.68, 95% CI 2.21–9.91, P<0.001). Moreover, LDL-BCD levels were positively and significantly correlated with interferon (IFN)-γ, whereas NO levels were inversely and significantly correlated with IFN-γ and Th1/Th2 ratio. Conclusion LDL-BCD and NO production seem to be associated with aggressive B-cell NHL and alteration of Th1/Th2 ratio. Our results have to be examined using ex vivo mechanistic studies leading to further investigations of these parameters, with an interest in the

  5. Androgen receptor inactivation contributes to antitumor efficacy of 17{alpha}-hydroxylase/17,20-lyase inhibitor 3beta-hydroxy-17-(1H-benzimidazole-1-yl)androsta-5,16-diene in prostate cancer.

    PubMed

    Vasaitis, Tadas; Belosay, Aashvini; Schayowitz, Adam; Khandelwal, Aakanksha; Chopra, Pankaj; Gediya, Lalji K; Guo, Zhiyong; Fang, Hong-Bin; Njar, Vincent C O; Brodie, Angela M H

    2008-08-01

    We previously reported that our novel compound 3beta-hydroxy-17-(1H-benzimidazole-1-yl)androsta-5,16-diene (VN/124-1) is a potent 17alpha-hydroxylase/17,20-lyase (CYP17) inhibitor/antiandrogen and strongly inhibits the formation and proliferation of human prostate cancer LAPC4 tumor xenografts in severe combined immunodeficient mice. In this study, we report that VN/124-1 and other novel CYP17 inhibitors also cause down-regulation of androgen receptor (AR) protein expression in vitro and in vivo. This mechanism of action seems to contribute to their antitumor efficacy. We compared the in vivo antitumor efficacy of VN/124-1 with that of castration and a clinically used antiandrogen, Casodex, and show that VN/124-1 is more potent than castration in the LAPC4 xenograft model. Treatment with VN/124-1 (0.13 mmol/kg twice daily) was also very effective in preventing the formation of LAPC4 tumors (6.94 versus 2410.28 mm(3) in control group). VN/124-1 (0.13 mmol/kg twice daily) and VN/124-1 (0.13 mmol/kg twice daily) + castration induced regression of LAPC4 tumor xenografts by 26.55% and 60.67%, respectively. Treatments with Casodex (0.13 mmol/kg twice daily) or castration caused significant tumor suppression compared with control. Furthermore, treatment with VN/124-1 caused marked down-regulation of AR protein expression, in contrast to treatments with Casodex or castration that caused significant up-regulation of AR protein expression. The results suggest that VN/124-1 acts by several mechanisms (CYP17 inhibition, competitive inhibition, and down-regulation of the AR). These actions contribute to inhibition of the formation of LAPC4 tumors and cause regression of growth of established tumors. VN/124-1 is more efficacious than castration in the LAPC4 xenograft model, suggesting that the compound has potential for the treatment of prostate cancer. PMID:18723482

  6. Crystal structure of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13SR)-13-benz­yloxy-7-meth­oxy­meth­oxy-11,15,18,18-tetra­methyl-3-oxo-2,4-dioxa­tetra­cyclo­[12.3.1.01,5.06,11]octa­deca-14,16-dien-10-yl benzoate

    PubMed Central

    Oishi, Takeshi; Fukaya, Keisuke; Yamaguchi, Yu; Sugai, Tomoya; Watanabe, Ami; Sato, Takaaki; Chida, Noritaka

    2015-01-01

    In the title compound, C36H42O8, the dioxolane ring adopts a twist conformation; the two adjacent C atoms deviate alternately from the mean plane of other atoms by −0.287 (5) and 0.174 (5) Å. The cyclo­hexane, cyclo­hexa­diene and central cyclo­octane rings show chair, half-chair and boat–chair forms, respectively. As a result of the strained ring system, the tetra­subsituted olefin in the cyclo­hexa­diene is skewed from an ideal planar structure. In the crystal, C—H⋯O hydrogen bonds connect the mol­ecules into a sheet parallel to (100). The sheets are further linked by other weak C—H⋯O and C—H⋯π inter­actions, forming a three-dimensional network. PMID:25995863

  7. Dichlorido-1κCl,3κCl-hexa­kis­[1,1,2,2,3,3(η5)-cyclo­penta­dien­yl]di-μ2-oxido-1:2κ2 O:O;2:3κ2 O:O-trizirconium(IV)

    PubMed Central

    Kraft, Bradley M.; Brennessel, William W.

    2012-01-01

    The title compound, [Zr3(C5H5)6Cl2O2], exists as discrete mol­ecules possessing a series of three Cp2Zr units (Cp is cyclo­penta­dien­yl) bridged by oxide ligands and end-capped by chloride ligands. The Cp planes in the central and terminal zirconocene units form dihedral angles of 53.3 (2) and 53.5 (2)°, respectively. The two Zr—O—Zr bridge angles are nearly linear and form a planar Zr3O2 core. The mol­ecule bears C2 symmetry with the central Zr atom lying on a crystallographic twofold axis. PMID:22807735

  8. catena-Poly[[bis­(ethanol-κO)mangan­ese(II)]-μ-2,5-di­chloro-3,6-di­oxo­cyclo­hexa-1,4-diene-1,4-bis­(olato)-κ4 O 1,O 6:O 3,O 4

    PubMed Central

    Tanaka, Seiya; Himegi, Akiko; Ohishi, Tomomi; Fuyuhiro, Akira; Kawata, Satoshi

    2014-01-01

    In the title coordination polymer, [Mn(C6Cl2O4)(C2H5OH)2]n, the MnII atom and the chloranilate [systematic name: 2,5-di­chloro-3,6-dioxo­cyclo­hexa-1,4-diene-1,4-bis­(olate)] ion lie on crystallographic inversion centers. The geometry around the MnII atom is a distorted octa­hedron involving four O atoms of two chloranilate ions and two O atoms from two ethanol mol­ecules. The chloranilate ion serves as a bridging ligand between the MnII ions, leading to an infinite linear chain along the b-axis direction. The chains are linked by O—H⋯O hydrogen bonds between the apically coordinating ethanol mol­ecule and the chloranilate ion, affording a two-dimensional layer expanding parallel to the ab plane. PMID:24764952

  9. [2,5-Bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene]dichloridomanganese(II): from a mononuclear compound to a three-dimensional supramolecular framework through C-H···Cl hydrogen bonds and π-π stacking interactions.

    PubMed

    Lu, Zhengliang; Zhao, Yuanchao; Chen, Baolian; Huang, Ximing; Fan, Chunhua

    2014-07-01

    The title compound, [MnCl2(C24H20N6)], has been synthesized and characterized based on the multifunctional ligand 2,5-bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene (L). The Mn(II) centre is five-coordinate with an approximately square-pyramidal geometry. The L ligand acts as a tridendate chelating ligand. The mononuclear molecules are bridged into a one-dimensional chain by two C-H···Cl hydrogen bonds. These chains are assembled into a two-dimensional layer through π-π stacking interactions between adjacent uncoordinated bipyridyl groups. Furthermore, a three-dimensional supramolecular framework is attained through π-π stacking interactions between adjacent coordinated bipyridyl groups. PMID:24992119

  10. Synthesis of Pyrazolo[5,1-a]isoindoles and Pyrazolo[5,1-a]isoindole-3-carboxamides through One-Pot Cascade Reactions of 1-(2-Bromophenyl)buta-2,3-dien-1-ones with Isocyanide and Hydrazine or Acetohydrazide.

    PubMed

    Tian, Miaomiao; He, Yan; Zhang, Xinying; Fan, Xuesen

    2015-08-01

    A novel and efficient method for the construction of the pyrazolo[5,1-a]isoindole scaffold via a one-pot three-component cascade reaction of 1-(2-bromophenyl)buta-2,3-dien-1-one with hydrazine and isocyanide promoted by a Pd catalyst is described. This cascade process proceeds through initial condensation of the allenic ketone with hydrazine followed by Pd-catalyzed isocyanide insertion into the C-Br bond and intramolecular C-N bond formation. Interestingly, when acetohydrazide was used in place of hydrazine, a more sophisticated procedure involving condensation, isocyanide insertion into C-H and C-Br bonds, deacetylation, and formation of C-C, C-O, and C-N bonds occurred to afford pyrazolo[5,1-a]isoindole-3-carboxamides with good efficiency. PMID:26153651

  11. Trichlorido{2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1-trimethyl­silyl-1H-imidazole-κN 3}titanium(IV) tetra­hydro­furan hemisolvate

    PubMed Central

    Ge, Fang; Nie, Wanli; Borzov, Maxim V.; Churakov, Andrei V.

    2010-01-01

    The title compound, [Ti(C15H23N2Si)Cl3]·0.5C4H8O, has been prepared from {2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1H-imidazolyl-κN 1}bis­(N,N-diethyl­amido-κN)titanium(IV), (C12H14N2)Ti(NEt2)2, by reaction with excess of Me3SiCl in tetra­hydro­furan (THF) at 353 K. The crystal structure contains THF as adduct solvent, disordered around a center of inversion. The presence of THF and the adduct ratio has been independently supported by 1H NMR spectroscopy. The coordination polyhedron of the Ti atom is distorted square-pyramidal, assuming the cyclo­penta­dienyl (Cp) ring occupies one coordination site. The Ti, Si and CH2 group C atoms only deviate slightly from the imidazole ring plane [by 0.021 (4), 0.133 (4) and 0.094 (4) Å, respectively]. Comparison of the principal geometric parameters with those of the few known structurally characterized analogues reveal small differences in bond lengths and angles at the Ti atom. The title complex is only stable in THF-d 8 in the presence of excess Me3SiCl, otherwise it exists in an equilibrium with equimolar amounts of dichlorido{2-[2-(η5-cyclo­penta­dien­yl)-2-methyl­prop­yl]-1H-imidazolyl-κN 3}titanium(IV) and chloro­trimethyl­silane. PMID:21579034

  12. Synthesis and pharmacological evaluations of new steroidal anti-inflammatory antedrugs: 9alpha-Fluoro-11beta,17alpha,21-trihydroxy-3,20-dioxo-pregna-1,4-diene-16alpha-carboxylate (FP16CM) and its derivatives.

    PubMed

    Park, Kwan-Kyun; Ko, Dong-Hoon; You, Zhengqing; Heiman, Ann S; Lee, Henry Joung

    2006-01-01

    In continuing efforts to develop potent anti-inflammatory steroids without systemic adverse effects, methyl 9alpha-fluoro-11beta,17alpha,21-trihydroxy-3,20-dioxo-pregna-1,4-diene-16alpha-carboxylate (FP16CM) and its 16-alkoxycarbonyl derivatives (FP16CE, FP16CP and FP16CB) were synthesized based on the antedrug concept. The steroids were evaluated for their pharmacological activities and adverse systemic effects. All steroidal antedrugs showed both binding affinity to the glucocorticoid receptor in liver cytosol and inhibitory effect on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophage cell. These compounds also inhibited croton-oil-induced ear edema and showed no systemic effects such as thymus atrophy and suppression of corticosterone level after 5-day treatment. Among those compounds tested, FP16CM showed the highest activities in receptor binding, NO inhibition and ear edema, these activities were comparable to those of prednisolone. Hydrolysis study in plasma showed that FP16CB was hydrolyzed rapidly, with the half-live (T1/2) of 3.2 min and the half-lives of other compounds were between 16.9 and 29.4 min. These results support the antedrug concept, of which the decrease in systemic adverse effects is attributed to fast hydrolysis to inactive metabolite in the systemic circulation. PMID:16280144

  13. "Bien Educado": Measuring the Social Behaviors of Mexican American Children

    ERIC Educational Resources Information Center

    Bridges, Margaret; Cohen, Shana R.; McGuire, Leah Walker; Yamada, Hiro; Fuller, Bruce; Mireles, Laurie; Scott, Lyn

    2012-01-01

    Young children's expected social behaviors develop within particular cultural contexts and contribute to their academic experience in large part through their relationships with their teachers. Commonly used measures focus on children's problem behaviors, developed from psychopathology traditions, and rarely situate normative and positive…

  14. Levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans in breast milk samples from three dioxin-contaminated hotspots of Vietnam.

    PubMed

    Manh, Ho Dung; Kido, Teruhiko; Tai, Pham The; Okamoto, Rie; Honma, Seijiro; Liang, Sun Xian; Anh, Le Thai; Maruzeni, Shoko; Nghi, Tran Ngoc; Nishijo, Muneko; Nakagawa, Hideaki; Nhu, Dang Duc; Van Tung, Dao; Hung, Nguyen Ngoc; Son, Le Ke

    2015-04-01

    We determined polychlorinated dibenzodioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in breast milk of 143 primiparae living around the three most dioxin-contaminated areas of Vietnam. The women sampled lived in the vicinity of former U.S. air bases at Bien Hoa (n=51), Phu Cat (n=23), and Da Nang (n=69), which are known as dioxin hotspots. Breast milk samples from Bien Hoa City, where residents live very close to the air base, showed high levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), with 18% of the samples containing >5 pgTCDD/g lipid. However, Phu Cat residents lived far from the air base and their samples showed lower TCDD levels, with none containing >5 pgTCDD/g lipid. In Da Nang, TCDD levels in mothers from Thanh Khe (close to the air base, n=43) were significantly higher than those in mothers from Son Tra (far from the air base, n=26), but not other PCDD and PCDF (PCDD/F) congeners. Although TCDD levels in Bien Hoa were the highest among these hotspots, levels of other PCDD/F congeners as well as the geometric mean concentration of total PCDD/F level in Bien Hoa (9.3 pg toxic equivalents [TEQ]/g lipid) were significantly lower than the level observed in Phu Cat (14.1 pgTEQ/g lipid), Thanh Khe (14.3 pgTEQ/g lipid), and Son Tra (13.9 pgTEQ/g lipid). Our findings indicated that residents living close to former U.S. air bases were exposed to elevated levels of TCDD, but not of other PCDD/F congeners. PMID:25569577

  15. Numerical Simulation of Petroleum Generation and Migration in the Song Hong Basin, Vietnam

    NASA Astrophysics Data System (ADS)

    Son, Byeong-Kook; Thi Nguyen, Hong; Park, Mee-Sook

    2014-05-01

    The numerical modeling of petroleum systems is an effective tool to understand generation, migration and accumulation of hydrocarbons in a sedimentary basin and hence to determine future targets for the hydrocarbon exploration. The numerical modeling identifies two petroleum systems in the Song Hong Basin, which is a petroliferous Cenozoic basin, offshore eastern Vietnam. These petroleum systems were named DinhCao-PhuCu(.) Petroleum System and SongHuong-BienDong(.) Petroleum System. DinhCao-PhuCu(.) Petroleum System covers northern and central parts of the Song Hong basin with Oligocene shale and coaly shale source rocks of Dinh Cao formation, which are dominated by type II-III kerogens. The hydrocarbon generation starts at 13 Ma within deeply buried Oligocene strata located in the centre of the basin. The hydrocarbon expels from the Oligocene source rock and migrates laterally and then up dip toward marginal areas where Middle Miocene sandstones of Phu Cu formation are present as major reservoirs. The numerical model shows that the critical moment occurs at about 3.5 Ma. The DinhCao-PhuCu(.) petroleum system is confirmed by sparse occurrence of oil and gas along the coast of eastern Vietnam. SongHuong-BienDong(.) Petroleum System is identified in limited areas of the central and southern Song Hong basin. The major source rock of this petroleum system is Lower Miocene dark claystones of Song Huong formation which contain gas prone, type III kerogen. The migration model shows that hydrocarbons are generated from the Miocene source rocks in the center of the basin at about 12 Ma, and migrates updip through sand bodies of Quang Ngai formation to the major boundaries faults, and further moves into highly permeable up-dipping units, the Bien Dong formation. The best depiction of the generation-migration-accumulation of hydrocarbons occurs at about 2 Ma. The presence of the SongHuong-BienDong(.) Petroleum System is indicated by the large gas fields in the central and

  16. New provincial records of skinks (Squamata: Scincidae) from northwestern Vietnam

    PubMed Central

    Pham, Anh Van; Le, Dzung Trung; Nguyen, Son Lan Hung; Ziegler, Thomas

    2015-01-01

    Abstract We report six new records of skinks from northwestern Vietnam: Eutropis macularius, Scincella devorator, S. monticola, S. ochracea, Sphenomorphus cryptotis and S. indicus. Our new findings increase the species number of skinks (Scincidae) to nine in Dien Bien Province and to 14 in Son La Province. We also provide additional natural history data of aforementioned species. PMID:25698899

  17. Silurian and Devonian in Vietnam—Stratigraphy and facies

    NASA Astrophysics Data System (ADS)

    Thanh, Tống Duy; Phương, Tạ Hoàng; Janvier, Philippe; Hùng, Nguyễn Hữu; Cúc, Nguyễn Thị Thu; Dương, Nguyễn Thùy

    2013-09-01

    Silurian and Devonian deposits in Viet Nam are present in several zones and regions, including Quang Ninh, East Bac Bo, and West Bac Bo Zones of the Bac Bo Region, the Dien Bien-Nghe An and Binh Tri Thien Zones of the Viet-Lao Region, and the South Trung Bo, and Western Nam Bo Zones of the South Viet Nam Region (Fig. 1). The main lithological features and faunal composition of the Silurian and Devonian Units in all these zones are briefly described. The Silurian consists of deep-water deposits of the upper parts of the Co To and Tan Mai Formations in the Quang Ninh Zone, the upper parts of the Phu Ngu Formation in the East Bac Bo Zone and the upper parts of the Long Dai and Song Ca Formations in the Viet-Lao Region. Shallow water facies Silurian units containing benthic faunas are more widely distributed, including the upper part of the Sinh Vinh and Bo Hieng Formations in the West Bac Bo Zone, the Kien An Formation in the Quang Ninh Zone, and, in the Viet-Lao Region, the Dai Giang Formation and the upper part of the Tay Trang Formation. No Lower and Middle Devonian deposits indicate deep water facies, but they are characterized by different shallow water facies. Continental to near shore, deltaic facies characterize the Lower Devonian Song Cau Group in the East Bac Bo Zone, the Van Canh Formation in the Quang Ninh Zone, and the A Choc Formation in the Binh Tri Thien Zone. Similar facies also occur in the Givetian Do Son Formation of the Quang Ninh Zone, and the Tan Lap Formation in the East Bac Bo Zone, and consist of coarse terrigenous deposits—cross-bedded conglomerates, sandstone, etc. Most Devonian units are characterized by shallow marine shelf facies. Carbonate and terrigenous-carbonate facies dominate, and terrigenous facies occur in the Lower and Middle Devonian sections in some areas only. The deep-water-like facies is characteriztic for some Upper Devonian formations in the Bac Bo (Bang Ca and Toc Tat Formations) and Viet-Lao Regions (Thien Nhan and

  18. Effect of ultimate pH on postmortem myofibrillar protein degradation and meat quality characteristics of Chinese Yellow crossbreed cattle.

    PubMed

    Li, Peng; Wang, Tiantian; Mao, Yanwei; Zhang, Yimin; Niu, Lebao; Liang, Rongrong; Zhu, Lixian; Luo, Xin

    2014-01-01

    This paper describes the complex effects of postmortem ultimate pH (pHu) on Chinese Yellow crossbreed cattle quality during postmortem ageing and provides an explanation of how pHu affects beef tenderness. High pHu beef had the highest initial tenderness (P < 0.05) compared with other groups at 1 day postmortem. Intermediate and low pHu beef had similar initial WBSF at 1 day postmortem, but intermediate pHu beef had slower tenderization rate than low pHu beef (P < 0.05). Purge loss, cooking loss, L*, a*, and b* values decreased with increasing pHu during ageing (P < 0.05). Myofibril fragmentation index (MFI) was higher in high pHu beef than intermediate and low pHu beef throughout ageing (P < 0.05). Protein degradation studies found that desmin and troponin-T appeared degraded within 0.5 h postmortem for high and low pHu beef, compared to >2 days for intermediate pHu beef. Overall, Chinese Yellow crossbred cattle tenderness is related to pHu, which may be affected by proteolytic enzymatic activity. Therefore, pHu may be used to predict beef tenderness and other quality characteristics during postmortem ageing. To achieve consistent tenderness, different ageing times should be used, depending on pHu. PMID:25197695

  19. Effect of Ultimate pH on Postmortem Myofibrillar Protein Degradation and Meat Quality Characteristics of Chinese Yellow Crossbreed Cattle

    PubMed Central

    Wang, Tiantian; Mao, Yanwei; Zhang, Yimin; Niu, Lebao; Liang, Rongrong; Zhu, Lixian; Luo, Xin

    2014-01-01

    This paper describes the complex effects of postmortem ultimate pH (pHu) on Chinese Yellow crossbreed cattle quality during postmortem ageing and provides an explanation of how pHu affects beef tenderness. High pHu beef had the highest initial tenderness (P < 0.05) compared with other groups at 1 day postmortem. Intermediate and low pHu beef had similar initial WBSF at 1 day postmortem, but intermediate pHu beef had slower tenderization rate than low pHu beef (P < 0.05). Purge loss, cooking loss, L*, a*, and b* values decreased with increasing pHu during ageing (P < 0.05). Myofibril fragmentation index (MFI) was higher in high pHu beef than intermediate and low pHu beef throughout ageing (P < 0.05). Protein degradation studies found that desmin and troponin-T appeared degraded within 0.5 h postmortem for high and low pHu beef, compared to >2 days for intermediate pHu beef. Overall, Chinese Yellow crossbred cattle tenderness is related to pHu, which may be affected by proteolytic enzymatic activity. Therefore, pHu may be used to predict beef tenderness and other quality characteristics during postmortem ageing. To achieve consistent tenderness, different ageing times should be used, depending on pHu. PMID:25197695

  20. An approach to mimicking the sesquiterpene cyclase phase by nickel-promoted diene/alkyne cooligomerization.

    PubMed

    Holte, Dane; Götz, Daniel C G; Baran, Phil S

    2012-01-20

    Artificially mimicking the cyclase phase of terpene biosynthesis inspires the invention of new methodologies, since working with carbogenic frameworks containing minimal functionality limits the chemist's toolbox of synthetic strategies. For example, the construction of terpene skeletons from five-carbon building blocks would be an exciting pathway to mimic in the laboratory. Nature oligomerizes, cyclizes, and then oxidizes γ,γ-dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) to all of the known terpenes. Starting from isoprene, the goal of this work was to mimic Nature's approach for rapidly building molecular complexity. In principle, the controlled oligomerization of isoprene would drastically simplify the synthesis of terpenes used in the medicine, perfumery, flavor, and materials industries. This article delineates our extensive efforts to cooligomerize isoprene or butadiene with alkynes in a controlled fashion by zerovalent nickel catalysis building off the classic studies by Wilke and co-workers. PMID:22229741

  1. EPDM polymers with intermolecular asymmetrical molecular weight, crystallinity and diene distribution

    SciTech Connect

    Datta, S.; Cheremishinoff, N.P.; Kresge, E.N.

    1993-12-31

    Rapid extrusion of EPDM elastomers require low viscosity and thus low molecular weights for the polymer. Efficient vulcanization of these elastomers requires network perfection and thus high molecular weights for the polymer. The benefits of these apparently mutually exclusive goals is important in uses of EPDM elastomers which require extrusion of profiles which are later cured. This paper shows that by introducing simultaneously asymmetry in the distribution of molecular weights, crystallinity and vulcanizable sites these apparently contradictory goals can be resolved. While these polymers cannot be made from a single Ziegler polymerization catalyst, the authors show the synthesis of these model EPDM polymers by blending polymers with very different molecular weights, ethylene and ENB contents. These blends can be rapidly extruded without melt fracture and can be cured to vulcanizates which have excellent tensile properties.

  2. Between ethylene and polyenes--the non-adiabatic dynamics of cis-dienes.

    PubMed

    Kuhlman, Thomas S; Glover, William J; Mori, Toshifumi; Møller, Klaus B; Martínez, Todd J

    2012-01-01

    Using Ab Initio Multiple Spawning (AIMS) with a Multi-State Multi-Reference Perturbation theory (MS-MR-CASPT2) treatment of the electronic structure, we have simulated the non-adiabatic excited state dynamics of cyclopentadiene (CPD) and 1,2,3,4-tetramethyl-cyclopentadiene (Me4-CPD) following excitation to S1. It is observed that torsion around the carbon-carbon double bonds is essential in reaching a conical intersection seam connecting S1 and S0. We identify two timescales; the induction time from excitation to the onset of population transfer back to S0 (CPD: -25 fs, Me4-CPD: -71 fs) and the half-life of the subsequent population transfer (CPD: -28 fs, Me4-CPD: -48 fs). The longer timescales for Me4-CPD are a kinematic consequence of the inertia of the substituents impeding the essential out-of-plane motion that leads to the conical intersection seam. A bifurcation is observed on S1 leading to population transfer being attributable, in a 5 : 2 ratio for CPD and 7 : 2 ratio for Me4-CPD, to two closely related conical intersections. Calculated time-resolved photoelectron spectra are in excellent agreement with experimental spectra validating the simulation results. PMID:23230770

  3. Bis(η(5)-penta-methyl-cyclo-penta-dien-yl)aluminium tetra-bromido-aluminate.

    PubMed

    Purdy, Andrew P; Dugger, Cherrelle; Butcher, Ray J

    2014-03-01

    The title compound, [Al(C10H15)2][AlBr4], was formed during the reduction of a mixture of Cp*AlBr2 and AlBr3. The Al(III) atoms of the two crystallographically independent cations each lie on an inversion center, and the [AlBr4](-) anions are on general positions. At 123 K, the structure exhibits disorder in two of the Br atoms of the [AlBr4](-) ion, with a ratio occupancy of 0.733 (6): 0.267 (3). In the crystal, there is possible weak hydrogen bonding between some methyl groups and Br atoms. The interactions link the moieties in a three-dimensional array. PMID:24764951

  4. An Approach to Mimicking the Sesquiterpene Cyclase Phase by Nickel-Promoted Diene/Alkyne Cooligomerization

    PubMed Central

    Holte, Dane; Götz, Daniel C. G.; Baran, Phil S.

    2012-01-01

    Artificially mimicking the cyclase phase of terpene biosynthesis inspires the invention of new methodologies, since working with carbogenic frameworks containing minimal functionality limits the chemist’s toolbox of synthetic strategies. For example, the construction of terpene skeletons from five-carbon building blocks would be an exciting pathway to mimic in the laboratory. Nature oligomerizes, cyclizes, and then oxidizes γ,γ-dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) to all of the known terpenes. Starting from isoprene, the goal of this work was to mimic Nature’s approach for rapidly building molecular complexity. In principle, the controlled oligomerization of isoprene would drastically simplify the synthesis of terpenes used in the medicine, perfumery, flavor, and materials industries. This article delineates our extensive efforts to cooligomerize isoprene or butadiene with alkynes in a controlled fashion by zero-valent nickel catalysis building off the classic studies by Günther Wilke and coworkers. PMID:22229741

  5. Nazarov reactions intercepted by (4 + 3) cycloadditions with oxygen-substituted dienes.

    PubMed

    LeFort, François M; Mishra, Vinayak; Dexter, Graham D; Morgan, Timothy D R; Burnell, D Jean

    2015-06-01

    The oxyallyl cation intermediate from the Lewis acid mediated Nazarov reaction of an allenyl vinyl ketone was intercepted by acyclic, 2-silyloxy-substituted butadienes by highly regioselective (4 + 3) cycloadditions. Stereoselectivity was often modest, but in some instances steric interactions were responsible for high selectivity. The results are consistent with concerted (4 + 3) cycloadditions. In many instances, the (4 + 3) products were susceptible to fragmentation or rearrangement in the presence of the Lewis acid. PMID:25984922

  6. Macrocyclic polyenynes: a stereoselective route to vinyl-ether-containing skipped diene systems.

    PubMed

    Ronson, Thomas O; Voelkel, Martin H H; Taylor, Richard J K; Fairlamb, Ian J S

    2015-05-11

    The stereoselective synthesis of a challenging macrocyclic polyene scaffold, containing a sensitive vinyl ether motif, has been accomplished using O,C-dilithiation/selective C-alkylation, Pd-catalysed etherification and Wittig reactions as key steps. An end-game macrocyclisation strategy employed a regio- and stereoselective Stille cross-coupling using Pd(Br)(N-Succ)(AsPh3)2 (AsCat) as the precatalyst. PMID:25891970

  7. World heritage site - Bien du Patrimoine Mondial - Kluane/Wrangell-St. Elias/Glacier Bay/Tatshenshini-Alsek

    USGS Publications Warehouse

    Labay, Keith A.; Wilson, Frederic H.

    2004-01-01

    The four parks depicted on this map make up a single World Heritage Site that covers 24.3 million acres. Together, they comprise the largest internationally protected land-based ecosystem on the planet. The United Nations Educational, Scientific and Cultural Organization (UNESCO) established the World Heritage Program in 1972 for the identification and protection of the world?s irreplaceable natural and cultural resources. World Heritage Sites are important as storehouses of memory and evolution, as anchors for sustainable tourism and community, and as laboratories for the study and understanding of the earth and culture. This World Heritage Site protects the prominent mountain ranges of Kluane, Wrangell, Saint Elias, and Chugach. It includes many of the tallest peaks on the continent, the world's largest non-polar icefield, extensive glaciers, vital watersheds, and expanses of dramatic wilderness. [Les quatre parcs figurant sur cette carte ne constituent qu?un seul site du patrimoine mondial recouvrant plus de 99 millions de km2, ce qui en fait le plus grand ecosysteme terrestre protege par loi internationale. En 1972, L?UNESCO (l?organisation des Nations Unies pour les sciences, l'education et la culture) a etabli le programme du patrimoine mondial afin d?identifier et de proteger les ressources naturelles et culturelles irremplacables de notre plan?te. Si les sites du patrimoine mondial sont si importants c'est parce qu'ils representent a la fois des livres ouverts sur l?histoire de la Terre, le point de depart du tourisme durable et du developpement des collectivites, des laboratoires pour etudier et comprendre la nature et la culture. Ce site du patrimoine mondial assure la protection des chaines de montagnes de Kluane, Wrangell, Saint Elias, et Chugach. On y trouve plusieurs des plus hauts sommets du continent, le plus grand champ de glace non-polaire du monde, d?immenses glaciers, des bassins hydrologiques essentiels, et de la nature sauvage a perte de vue.

  8. Canada's Kids: Thriving? Or Just Surviving? = Les enfants du Canada: Se developpent-ils bien ou vivotent-ils simplement?

    ERIC Educational Resources Information Center

    McCloskey, Donna, Ed.

    1997-01-01

    This quarterly journal issue (in English and French versions) includes the following articles: (1) "Canada's Kids: Thriving? Or Just Surviving?" (McCloskey, Donna), an overview of the latest research on the well-being of Canada's children; (2) "The Fence at the Edge of the Cliff: Approaching Family Policy in Canada" (Mirabelli, Alan), which…

  9. A cocrystal of 3α-hy­droxy­tirucalla-8,24-dien-21-oic acid and 3β-fluoro­tirucalla-7,24-dien-21-oic acid (0.897:0.103)

    PubMed Central

    Yousuf, S.; Kamdem, R. S. T.; Wafo, P.; Ngadjui, B. T.; Fun, Hoong-Kun

    2011-01-01

    The title compound, 0.897C30H48O3.0.103C30H47O2F is a co-crystal of two triterpenes isolated from the resin of Canarium schweinfurthiiand Engl. Both triterpenes consists of four trans-fused rings having chair/half-chair/half-chair and envelope conformations. The mol­ecular conformations are stabilized by intra­molecular C—H⋯O hydrogen bonds, forming rings of S(7) graph-set motif. In the crystal, mol­ecules are linked by inter­molecular O—H⋯O and C—H⋯O inter­actions, forming sheets parallel to (001). All atoms. excepting the axially-oriented hydroxyl group in the major component and the equatorially-oriented fluorine atom in the minor component, are overlapping. PMID:21754032

  10. A cocrystal of 3α-hy-droxy-tirucalla-8,24-dien-21-oic acid and 3β-fluoro-tirucalla-7,24-dien-21-oic acid (0.897:0.103).

    PubMed

    Yousuf, S; Kamdem, R S T; Wafo, P; Ngadjui, B T; Fun, Hoong-Kun

    2011-04-01

    The title compound, 0.897C(30)H(48)O(3).0.103C(30)H(47)O(2)F is a co-crystal of two triterpenes isolated from the resin of Canarium schweinfurthiiand Engl. Both triterpenes consists of four trans-fused rings having chair/half-chair/half-chair and envelope conformations. The mol-ecular conformations are stabilized by intra-molecular C-H⋯O hydrogen bonds, forming rings of S(7) graph-set motif. In the crystal, mol-ecules are linked by inter-molecular O-H⋯O and C-H⋯O inter-actions, forming sheets parallel to (001). All atoms. excepting the axially-oriented hydroxyl group in the major component and the equatorially-oriented fluorine atom in the minor component, are overlapping. PMID:21754032

  11. 11,20-Dihy­droxy-3-oxopregna-1,4-dien-21-oic acid monohydrate

    PubMed Central

    Guo, Zhanqiang; Tang, Shengan; Duan, Hongquan

    2011-01-01

    The title compound, C21H28O5·H2O, is the hydrate of a steroid derivative and was obtained by degradation of solid prednisolone sodium phosphate. The six C atoms in ring A are nearly co-planar with a mean deviation of 0.015 Å. Rings B and C are both in chair conformations, while ring D has an envelope form. In the crystal, inter­molecular O—H⋯O hydrogen-bonding inter­actions occur between the hy­droxy groups, carbonyl O atoms and solvent water mol­ecules, resulting in an overall three-dimensional structure. PMID:21754697

  12. From supramolecular polymersomes to stimuli-responsive nano-capsules based on poly(diene-b-peptide) diblock copolymers

    NASA Astrophysics Data System (ADS)

    Chécot, F.; Lecommandoux, S.; Klok, H.-A.; Gnanou, Y.

    2003-01-01

    This paper discusses the self-assembly of block copolymers into vesicular morphology. After a brief state of art of the field, a system based on an amphiphilic poly(butadiene)-b-poly(γ-L-glutamic acid) (PB-b-PGA) diblock copolymer in aqueous solution is discussed in detail. The aggregation behavior of this block copolymer has been investigated by means of fluorescence spectroscopy, dynamic (DLS) and static (SLS) light scattering as well as transmission electron microscopy (TEM). The diblock copolymer was found to form well-defined vesicles in water. The size of these so-called polymersomes or peptosomes could be reversibly manipulated as a function of both pH and ion strength. Depending on the pH of the aqueous solution, the hydrodynamic radii of these vesicles were found to vary from 100 nm to 150 nm. By cross-linking the 1,2-vinyl double bonds present in the polybutadiene block, the ability to transform a transient supramolecular self-organized aggregate into a permanent “shape-persistent stimuli-responsive nanoparticle” has been demonstrated.

  13. Diels-Alder Trapping of Photochemically Generated Dienes with Acrylic Esters: A Novel Approach to Photocured Polymer Film Development

    NASA Technical Reports Server (NTRS)

    Ilhan, Faysal; Tyson, Daniel S.; Smith, Deedee; Meador, Mary Ann; Meador, Michael A.

    2004-01-01

    Diels-Alder cycloadditions have often been utilized in polymer synthesis as an alternative to condensation reactions. In our earlier efforts, we developed a new method for the preparation of linear aromatic polyimides, which employs o-quionodimethanes (o-QDMs), generated by a well-known photochemical reaction: the photoenolization of o-methylphenyl ketones. Photolysis of o-methylbenzophenone 1 produces hydroxy-o-quino- diemthane 2, which can be trapped with dienophiles, such as dimethyl acetylenedicarboxylate, to efficiently yield the corresponding cycloadduct (Scheme 1). Here we extend this approach to a novel photocuring process for development of polymer films. We synthesized a series of molecules with multi o-mehtylphenyl ketone functionalities. We further investigated these molecules as photoreactive monomers to obtain polyester films through Diels-Alder cycloadditions.

  14. Mechanistic interpretation of selective catalytic hydrogenation and isomerization of alkenes and dienes by ligand deactivated Pd nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhu, Jie S.; Shon, Young-Seok

    2015-10-01

    Unsupported thiolate-capped palladium nanoparticle catalysts are found to be highly substrate-selective for alkene hydrogenation and isomerization. Steric and poisoning effects from thiolate ligands on the nanoparticle surface control reactivity and selectivity by influencing alkene adsorption and directing either di-σ or mono-σ bond formation. The presence of overlapping p orbitals and α protons in alkenes greatly influences the catalytic properties of deactivated palladium nanoparticles leading to easily predictable hydrogenation or isomerization products.Unsupported thiolate-capped palladium nanoparticle catalysts are found to be highly substrate-selective for alkene hydrogenation and isomerization. Steric and poisoning effects from thiolate ligands on the nanoparticle surface control reactivity and selectivity by influencing alkene adsorption and directing either di-σ or mono-σ bond formation. The presence of overlapping p orbitals and α protons in alkenes greatly influences the catalytic properties of deactivated palladium nanoparticles leading to easily predictable hydrogenation or isomerization products. Electronic supplementary information (ESI) available: Supplementary figures, methods, materials, and characterization data. See DOI: 10.1039/c5nr05090a

  15. Erratum: Di-μ-nitrosyl-bis-[(η-penta-methyl-cyclo-penta-dien-yl)ruthenium(0)](Ru-Ru). Corrigendum.

    PubMed

    Pearsal, Matthew; Gembicky, Milan; Dominiak, Paulina; Larsen, Anna; Coppens, Philip

    2010-01-01

    The acknowledgement in the paper by Pearsal, Gembicky, Dominiak, Larsen & Coppens [Acta Cryst. (2007), E63, m2596] is extended and an omitted reference is added.[This corrects the article DOI: 10.1107/S1600536807045321.]. PMID:21578980

  16. 17β-Hy­droxy-17α-methyl­androsta-1,4-dien-3-one

    PubMed Central

    Karpinska, Jolanta; Erxleben, Andrea; McArdle, Patrick

    2013-01-01

    The title compound, C20H28O2, is a steroid with strong anabolic properties. The present solvent-free form crystallizes with two mol­ecules per asymmetric unit. In the crystal, both mol­ecules are involved in the formation of O—H⋯O hydrogen-bonded chains which extend along the b-axis direction. PMID:23476441

  17. 3,8-Dimethyl-4,7-diaza-deca-3,7-diene-2,9-dione dioxime.

    PubMed

    Achiwawanich, Supakit; Duangtongyou, Tanwawan; Pakawatchai, Chaveng; Siripaisarnpipat, Sutatip

    2010-01-01

    The complete mol-ecule of the title compound, C(10)H(18)N(4)O(2), is generated by a crystallographic inversion centre at the mid-point of the central C-C bond. The two oxime groups have an E configuration. In the crystal, mol-ecules are linked through inter-molecular O-H⋯N hydrogen bonds. PMID:21522645

  18. 3,8-Dimethyl-4,7-diaza­deca-3,7-diene-2,9-dione dioxime

    PubMed Central

    Achiwawanich, Supakit; Duangtongyou, Tanwawan; Pakawatchai, Chaveng; Siripaisarnpipat, Sutatip

    2011-01-01

    The complete mol­ecule of the title compound, C10H18N4O2, is generated by a crystallographic inversion centre at the mid-point of the central C—C bond. The two oxime groups have an E configuration. In the crystal, mol­ecules are linked through inter­molecular O—H⋯N hydrogen bonds. PMID:21522645

  19. Observing the orbital ordering of Ti(III) ions in catalysts for the polymerization of diene compounds

    NASA Astrophysics Data System (ADS)

    Biktagirov, V. V.; Anufrienko, V. F.; Biktagirova, E. V.

    2016-02-01

    The orbital ordering of Ti(III) ions is observed via EPR spectroscopy for the catalytic system TiCl4 + TIBA in an isopentane solution with an excess of organoaluminum compound. A model of the alternating ground states of 3 d 1 ions ( d xy and d_{z^2 } is proposed for the ordered structures. Ti(III) ions with the d xy ground states are mono- and dialkylated.

  20. 77 FR 64102 - Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Amended Final Results and Partial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-18

    ... FR 55800 (September 11, 2012) (``Final Results''). On September 17, 2012, the Minh Phu Group,\\2\\ Phu... of Vietnam: Preliminary Results of Administrative Review, 77 FR 13547 (March 7, 2012) (``Preliminary....; Versaggi Shrimp Co.; and Craig Wallis. \\8\\ See Preliminary Results, 77 FR at 13548. These amended...

  1. Katimavik Participant's Manual, Book VIII, Nutrition and Well-Being = Katimavik manuel du participant, cahier VIII, l'alimentation et le bien-etre.

    ERIC Educational Resources Information Center

    Crelinsten, Michael, Ed.

    The bilingual student manual focuses on the nutrition and well-being learning activity portion of Katimavik, a nine-month volunteer community service and experiential learning program for 17 to 21 year old Canadians. Providing participants with basic information and tools to assess and improve nutritional states and tie nutrition concerns into a…

  2. Grassroots Action Research and the Greater Good (La investigación acción de base y el bien mayor)

    ERIC Educational Resources Information Center

    Rainey, Isobel

    2011-01-01

    This study examines the action research topics and topic preferences of two groups of grassroots teachers: active researchers, and potential researchers. The analysis of the topics appears to indicate that, over the past decade, action research at the teaching of English at the grassroots level to speakers of other languages has been principally…

  3. Complexation of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-diene dithiocyanate with nickel (II) acetate

    SciTech Connect

    Ishak, Nur Iliyani Mohd; Yamin, Bohari M.

    2013-11-27

    The complexation of nickel acetate with tetraaza involves deprotonation of protonated amine nitrogen to form neutral ligand coordinated to the nickel via the four nitrogen atom. The dication complex is paired with thiocyanate anions. The complex was characterized by elemental analysis, UV-VIS and FTIR spectroscopic method. The crystal structure of nickel complex characterized by X-Ray crystallography and adopts square planar geometry.

  4. Addition polymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and Bis-dienes: Processable resins for high temperature application

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.

    1987-01-01

    1,4,5,8-Tetrahydro-1,4;5,8-diepoxyanthracene reacts with various anthracene endcapped polyimide oligomers to form Diels-Alder cycloaddition copolymers. The polymers are soluble in common organic solvents, and have molecular weights of approximately 21,000 to 32,000. Interestingly, these resins appear to be more stable in air then in nitrogen. This is shown to be due to a unique dehydration (loss of water ranges from 2 to 5 percent) at temperatures of 390 to 400 C to give thermo-oxidatively stable pentiptycene units along the polymer backbone. Because of their high softening points and good thermo-oxidative stability, the polymers have potential as processible, matrix resins for high temperature composite applications.

  5. (1E,3E)-1,4-Bis(4-meth­oxy­phen­yl)buta-1,3-diene

    PubMed Central

    Narayan, Gopinathan; Rath, Nigam P.; Das, Suresh

    2010-01-01

    The title compound, C18H18O2, which exhibits blue emission in the solid state, is an inter­mediate in the preparation of liquid crystals and polymers. The mol­ecule is located on an inversion centre. In the crystal, mol­ecules are arranged in a herringbone motif. PMID:21587646

  6. Diversification of ortho-Fused Cycloocta-2,5-dien-1-one Cores and Eight- to Six-Ring Conversion by σ Bond C-C Cleavage.

    PubMed

    Eccleshare, Lee; Lozada-Rodríguez, Leticia; Cooper, Phillippa; Burroughs, Laurence; Ritchie, John; Lewis, William; Woodward, Simon

    2016-08-22

    Sequential treatment of 2-C6 H4 Br(CHO) with LiC≡CR(1) (R(1) =SiMe3 , tBu), nBuLi, CuBr⋅SMe2 and HC≡CCHClR(2) [R(2) =Ph, 4-CF3 Ph, 3-CNPh, 4-(MeO2 C)Ph] at -50 °C leads to formation of an intermediate carbanion (Z)-1,2-C6 H4 {CA (=O)C≡CB R(1) }{CH=CH(CH(-) )R(2) } (4). Low temperatures (-50 °C) favour attack at CB leading to kinetic formation of 6,8-bicycles containing non-classical C-carbanion enolates (5). Higher temperatures (-10 °C to ambient) and electron-deficient R(2) favour retro σ-bond C-C cleavage regenerating 4, which subsequently closes on CA providing 6,6-bicyclic alkoxides (6). Computational modelling (CBS-QB3) indicated that both pathways are viable and of similar energies. Reaction of 6 with H(+) gave 1,2-dihydronaphthalen-1-ols, or under dehydrating conditions, 2-aryl-1-alkynylnaphthlenes. Enolates 5 react in situ with: H2 O, D2 O, I2 , allylbromide, S2 Me2 , CO2 and lead to the expected C-E derivatives (E=H, D, I, allyl, SMe, CO2 H) in 49-64 % yield directly from intermediate 5. The parents (E=H; R(1) =SiMe3 , tBu; R(2) =Ph) are versatile starting materials for NaBH4 and Grignard C=O additions, desilylation (when R(1) =SiMe) and oxime formation. The latter allows formation of 6,9-bicyclics via Beckmann rearrangement. The 6,8-ring iodides are suitable Suzuki precursors for Pd-catalysed C-C coupling (81-87 %), whereas the carboxylic acids readily form amides under T3P® conditions (71-95 %). PMID:27452351

  7. N′-[(1E,2E)-3,7-Dimethyl­octa-2,6-dien-1-yl­idene]pyridine-4-carbohydrazide

    PubMed Central

    Bhat, Mashooq A.; Abdel-Aziz, Hatem A.; Ghabbour, Hazem A.; Hemamalini, Madhukar; Fun, Hoong-Kun

    2012-01-01

    In the title compound, C16H21N3O, the mol­ecule adopts an E conformation about the central C=N double bond. The 2-methyl­pent-2-ene group is disordered over two sets of sites, with a refined occupancy ratio of 0.785 (8):0.215 (8). The dihedral angle between the essentially planar [the r.m.s. value for the major component is 0.021 (7) and its maximum deviation is 0.025 (4) Å; the r.m.s. value for the minor component is 0.03 (4) and its maximum deviation is 0.05 (3) Å] major and minor components of the 2-methyl­but-2-ene group is 35.9 (13)°. In the crystal, C—H⋯O and N—H⋯O hydrogen bonds link the molecules, with the same O atom acting as the acceptor. This results in C 1 1(4) and C 1 1(5) [001] chains. PMID:22606092

  8. The Isomerization of Δ5-Androstene-3,17-dione by the Human Glutathione Transferase A3-3 Proceeds via a Conjugated Heteroannular Diene Intermediate*

    PubMed Central

    Daka, Jonathan L.; Achilonu, Ikechukwu; Dirr, Heini W.

    2014-01-01

    The seemingly simple proton abstraction reactions underpin many chemical transformations, including isomerization reactions, and are thus of immense biological significance. Despite the energetic cost, enzyme-catalyzed proton abstraction reactions show remarkable rate enhancements. The pathways leading to these accelerated rates are numerous and on occasion partly enigmatic. The isomerization of the steroid Δ5-androstene-3,17-dione by the glutathione transferase A3-3 in mammals was investigated to gain insight into the mechanism. Particular emphasis was placed on the nature of the transition state, the intermediate suspected of aiding this process, and the hydrogen bonds postulated to be the stabilizing forces of these transient species. The UV-visible detection of the intermediate places this species in the catalytic pathway, whereas fluorescence spectroscopy is used to obtain the binding constant of the analog intermediate, equilenin. Solvent isotope exchange reveals that proton abstraction from the substrate to form the intermediate is rate-limiting. Analysis of the data in terms of the Marcus formalism indicates that the human glutathione transferase A3-3 lowers the intrinsic kinetic barrier by 3 kcal/mol. The results lead to the conclusion that this reaction proceeds through an enforced concerted mechanism in which the barrier to product formation is kinetically insignificant. PMID:25248748

  9. Selective hydrogenation of dienes and alkynes to alkenes in the presence of products of the reaction of bis-. pi. -allylpalladium chloride with amines

    SciTech Connect

    Cherkashin, G.M.; Shuikina, L.P.; Parenago, O.P.; Frolov, V.M.

    1987-06-01

    The authors have shown that the interaction of bis-..pi..-allylpalladium chloride with primary or secondary amines containing alkyl groups of substantial size (octyl- or dioctylamine) in toluene medium leads to the formation of palladium complexes active in the homogeneous catalytic hydrogenation of unsaturated hydrocarbons.

  10. Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

    PubMed Central

    Edmunds, Michael; Raheem, Mohammed Abdul; Boutin, Rebecca; Tait, Katrina

    2016-01-01

    Summary Palladium-catalyzed ring-opening reactions of C1 substituted 7-oxanorbornadiene derivatives with aryl iodides were investigated. The optimal conditions for this reaction were found to be PdCl2(PPh3)2, ZnCl2, Et3N and Zn in THF. Both steric and electronic factors played a role in the outcome of the reaction as increasing the steric bulk on the bridgehead carbon decreased the yield. These reactions were found to be highly regioselective, giving only one of the two possible regioisomers in all cases. A diverse collection of novel, highly substituted biphenyl derivatives were obtained. PMID:26977182

  11. Crystal structure of 15,16-ep-oxy-7β,9α-di-hydroxy-labdane-13(16),14-dien-6-one.

    PubMed

    Singh, Vikram Dev; Kamni; Amina, Musarat; Al-Musayeib, Nawal; Anthal, Sumati; Kant, Rajni

    2015-07-01

    In the title mol-ecule, C20H30O4, both cyclo-hexane rings adopt chair conformations. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds forming chains along [100]. In addtion, an intra-molecular O-H⋯O hydrogen bond forms an S(5) ring. PMID:26279920

  12. Complexation of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-diene dithiocyanate with nickel (II) acetate

    NASA Astrophysics Data System (ADS)

    Ishak, Nur Iliyani Mohd; Yamin, Bohari M.

    2013-11-01

    The complexation of nickel acetate with tetraaza involves deprotonation of protonated amine nitrogen to form neutral ligand coordinated to the nickel via the four nitrogen atom. The dication complex is paired with thiocyanate anions. The complex was characterized by elemental analysis, UV-VIS and FTIR spectroscopic method. The crystal structure of nickel complex characterized by X-Ray crystallography and adopts square planar geometry.

  13. CATALYZED CYCLIZATION OF [ALPHA],[OMEGA]-DIENES: A VERSATILE PROTOCOL FOR THE SYNTHESIS OF FUNCTIONALIZED CARBOCYCLIC AND HETEROCYCLIC COMPOUNDS. (R826120)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  14. Processable, high temperature polymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and bis-dienes

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.

    1988-01-01

    1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene reacts with various anthracene end-capped polyimide oligomers to form Diels-Alder cycloaddition copolymers. The polymers are soluble in common organic solvents, and have molecular weights of approximately 21,000 to 32,000. These resins exhibit lower weight loss in air than in nitrogen. This is suggested to be due to dehydration (loss of water ranges from 2 to 5 percent) at temperatures of 390 to 400 C to give thermooxidatively stable pentiptycene units along the polymer backbone. Because of their high softening points and good thermooxidative stability, the polymers have potential as processable, matrix resins for high temperature composite applications.

  15. 40 CFR 721.6900 - Polymer of bisphenol A di-glyc-i-dal ether, substituted al-kenes, and but-a-diene.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymer of bisphenol A di-glyc-i-dal... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6900 Polymer of bisphenol A di-glyc-i... subject to reporting. (1) The chemical substances identified generically as polymer of bisphenol...

  16. 6-(2-Hydroxy­anilinomethyl­ene)-4-nitro­cyclo­hexa-2,4-dien-1-one

    PubMed Central

    Böhme, Uwe; Fels, Sabine

    2008-01-01

    The molecule of the title compound, C13H10N2O4, is nearly planar with a dihedral angle between the two aromatic rings of 2.24 (9)°. The NH group forms an intramolecular hydrogen bond with the carbonyl O atom. The mol­ecules form dimers about inversion centers in the crystal structure via inter­molecular O—H⋯O hydrogen bonds. PMID:21200741

  17. Effect of chronic aluminum exposure on the levels of conjugated dienes and enzymatic antioxidants in hippocampus and whole brain of rat

    SciTech Connect

    Gupta, A.; Shukla, G.S.

    1995-11-01

    The reported association between elevated tissue levels of aluminum (Al) and certain human neurological disorders have evoked increasing attention on the neurotoxic effects of aluminum. High levels of Al have been reported in hippocampal neurons comprising neurofibrillary tangles in senile dementia of Alzheimer`s type, amyotropic lateral sclerosis and Parkinsonian dementia of Guam. Aluminum is considered to be the causal factor for a high incidence of dialysis encephalopathy. It has been shown that the incidence of Alzheimer`s disease was higher in places with a high Al content in drinking water compared to low level areas. Varied uses of Al in pharmaceutical preparations, foods, water purification and many house-hold items have increased the risk of its exposure to general population. The exposure may be as high as 500 mg/kg/day in children with uremia who are treated with Al containing phosphate binding gels. Aluminum ingestion in humans and experimental animals have been reported to produce behavioural dysfunctions. The mechanism of al neurotoxicity is not understood at present. Attempts made in this direction have reported its interaction with blood-brain barrier function, decreased membrane fluidity, glutathione depletion and increased brain lipid peroxidation. These studies indicate the possibility that oxidative stress may be one of the possible mechanisms of Al-induced neurotoxicity. Since Al has been reported to be in high concentrations in hippocampal neurons in certain neurological diseases and there is wealth of evidence implicating hippocampal impairment and memory dysfunction, we attempted to investigate the effect of chronic Al intoxication on the status of enzymatic antioxidants and the extent of peroxidative damage in hippocampus and whole brain of rat. 16 refs., 4 figs., 1 tab.

  18. Diels-Alder Cycloadditions: A MORE Experiment in the Organic Laboratory Including a Diene Identification Exercise Involving NMR Spectroscopy and Molecular Modeling

    ERIC Educational Resources Information Center

    Shaw, Roosevelt; Severin, Ashika; Balfour, Miguel; Nettles, Columbus

    2005-01-01

    Two Diels-Alder reactions are described that are suitable for a MORE (microwave-induced organic reaction enhanced) experiment in the organic chemistry laboratory course. A second experiment in which the splitting patterns of the vinyl protons in the nuclear magnetic resonance (NMR) spectra of two MORE adducts are used in conjunction with molecular…

  19. 40 CFR 721.6900 - Polymer of bisphenol A di-glyc-i-dal ether, substituted al-kenes, and but-a-diene.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymer of bisphenol A di-glyc-i-dal... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6900 Polymer of bisphenol A di-glyc-i... subject to reporting. (1) The chemical substances identified generically as polymer of bisphenol...

  20. 40 CFR 721.6900 - Polymer of bisphenol A di-glyc-i-dal ether, substituted al-kenes, and but-a-diene.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymer of bisphenol A di-glyc-i-dal... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6900 Polymer of bisphenol A di-glyc-i... subject to reporting. (1) The chemical substances identified generically as polymer of bisphenol...

  1. 40 CFR 721.6900 - Polymer of bisphenol A di-glyc-i-dal ether, substituted al-kenes, and but-a-diene.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymer of bisphenol A di-glyc-i-dal... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6900 Polymer of bisphenol A di-glyc-i... subject to reporting. (1) The chemical substances identified generically as polymer of bisphenol...

  2. 40 CFR 721.6900 - Polymer of bisphenol A di-glyc-i-dal ether, substituted al-kenes, and but-a-diene.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymer of bisphenol A di-glyc-i-dal... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6900 Polymer of bisphenol A di-glyc-i... subject to reporting. (1) The chemical substances identified generically as polymer of bisphenol...

  3. A purple odyssey: synthesis and structure of 3-amino-4-hy-droxy-6-oxo-cyclo-hexa-2,4-dien-1-iminium chloride monohydrate.

    PubMed

    Plater, M John; Harrison, William T A

    2016-05-01

    In the cation of the title hydrated mol-ecular salt, C6H7N2O2 (+)·Cl(-)·H2O, the six-membered ring shows unequal bond lengths consistent with delocalization of electrons over two separate 6π systems with single bonds between them. In the crystal, the components are linked by N-H⋯Cl, N-H⋯O, O-H⋯Cl and O-H⋯O hydrogen bonds, generating double layers propagating in (100). PMID:27307999

  4. Characterization of the first-in-class T-cell-engaging bispecific single-chain antibody for targeted immunotherapy of solid tumors expressing the oncofetal protein claudin 6

    PubMed Central

    Stadler, Christiane R.; Bähr-Mahmud, Hayat; Plum, Laura M.; Schmoldt, Kathrin; Kölsch, Anne C.; Türeci, Özlem; Sahin, Ugur

    2016-01-01

    abstract The fetal tight junction molecule claudin 6 (CLDN6) is virtually absent from any normal tissue, whereas it is aberrantly and frequently expressed in various cancers of high medical need. We engineered 6PHU3, a T-cell-engaging bispecific single chain molecule (bi-(scFv)2) with anti-CD3/anti-CLDN6 specificities, and characterized its pharmacodynamic properties. Our data show that upon engagement by 6PHU3, T cells strongly upregulate cytotoxicity and activation markers, proliferate and acquire an effector phenotype. 6PHU3 exerts potent killing of cancer cells in vitro with EC50 values in the pg/mL range. Subcutaneous xenograft tumors in NSG mice engrafted with human PBMCs are eradicated by 6PHU3 treatment and survival of mice is significantly prolonged. Tumors of 6PHU3-treated mice are strongly infiltrated with activated CD4+, CD8+ T cells and TEM type cells but not Tregs and display a general activation of a mostly inflammatory phenotype. These effects are only observed upon bispecific but not monospecific engagement of 6PHU3. Together with the exceptionally cancer cell selective expression of the oncofetal tumor marker CLDN6, this provides a safeguard with regard to toxicity. In summary, our data shows that the concept of T-cell redirection combined with that of highly selective targeting of CLDN6-positive solid tumors is effective. Thus, exploring 6PHU3 for clinical therapy is warranted. PMID:27141353

  5. Impact of divergent selection for ultimate pH of pectoralis major muscle on biochemical, histological, and sensorial attributes of broiler meat.

    PubMed

    Alnahhas, N; Le Bihan-Duval, E; Baéza, E; Chabault, M; Chartrin, P; Bordeau, T; Cailleau-Audouin, E; Meteau, K; Berri, C

    2015-09-01

    The impact of divergent selection based on the ultimate pH (pHu) of pectoralis major (P. major) muscle on the chemical, biochemical, and histological profiles of the muscle and sensorial quality of meat was investigated in broiler chickens. The protein, lipid, DM, glycogen and lactate content, glycolytic potential, proteolysis, lipid and protein oxidation index, muscle fiber cross-sectional area, capillary density, and collagen surface were determined on the breast P. major muscle of 6-wk-old broilers issued from the high-pHu (pHu+) and low-pHu (pHu-) lines. Sensory attributes were also evaluated on the breast (roasted or grilled) and thigh (roasted) meat of the 2 lines. Protein, lipid, and DM content of P. major muscle were not affected by selection ( > 0.05). However, the P. major muscle of the pHu+ line was characterized by lower residual glycogen (-16%; ≤ 0.001) and lactate (-14%; ≤ 0.001) content and lower glycolytic potential (-14%; ≤ 0.001) compared with the pHu- line. Although the average cross-sectional area of muscle fibers and surface occupied by collagen were similar ( > 0.05) in both lines, fewer capillaries per fiber (-15%; ≤ 0.05) were observed in the pHu+ line. The pHu+ line was also characterized by lower lipid oxidation (thiobarbituric acid reactive substance index: -23%; ≤ 0.05) but protein oxidation and proteolysis index were not different ( > 0.05) between the 2 lines. At the sensory level, selection on breast muscle pHu mainly affected the texture of grilled and roast breast meat, which was judged significantly more tender ( ≤ 0.001) in the pHu+ line, and the acid taste, which was less pronounced in the roasted breast meat of the pHu+ line ( ≤ 0.002). This study highlighted that selection based on pHu does not affect the chemical composition and structure of breast meat. However, by modifying muscle blood supply and glycogen turnover, it affects meat acidity and oxidant status, both of which are likely to contribute to the large

  6. Early on-line classification of beef carcasses based on ultimate pH by near infrared spectroscopy.

    PubMed

    Reis, Marlon M; Rosenvold, Katja

    2014-02-01

    Prediction of ultimate pH (measured 48 h post mortem; pH(u)) in beef from Visible-near infrared (VIS-NIR) spectra collected 20 to 40 min post mortem was assessed. Spectra were collected from carcasses (cows: n = 86, bulls: n = 170, steers: n = 363, and heifers: n = 38) in a commercial hot boning abattoir under routine conditions. Partial Least Squares (PLS) models showed limited accuracy with RMSE for validation equal to 0.26, 0.20 and 0.36 for the All-animals, Non-bulls and Bulls models, respectively. The pH(u)-PLS-predicted values were used to segregate carcasses as normal (pH(u)<5.8) or high (pH(u) ≥ 5.8) showing better performance, by correctly classifying at least 90% of high pH(u) carcasses. The Non-bulls model was equivalent to the current technology used in the abattoir to classify carcasses based on pH(u). Thus near infrared spectroscopy (NIRS) could be used for on-line classification of beef carcasses based on pH(u). PMID:24211544

  7. Metabolic engineering of E.coli for the production of a precursor to artemisinin, an anti-malarial drug [Chapter 25 in Manual of Industrial Microbiology and Biotechnology, 3rd edition

    SciTech Connect

    Petzold, Christopher; Keasling, Jay

    2011-07-18

    This document is Chapter 25 in the Manual of Industrial Microbiology and Biotechnology, 3rd edition. Topics covered include: Incorporation of Amorpha-4,11-Diene Biosynthetic Pathway into E. coli; Amorpha-4,11-Diene Pathway Optimization; "-Omics" Analyses for Increased Amorpha-4,11-Diene Production; Biosynthetic Oxidation of Amorpha-4,11-Diene.

  8. The Development of a Taxonomy of the Life Skills Required to Become a Balanced Self-Determined Person = Essaie de Classification des Competences Necessaires pour Devenir une Personne Autonome et Bien Equilibree.

    ERIC Educational Resources Information Center

    Smith, Paul

    Intended for use by life skills coaches and students, program evaluators, and individuals developing lesson plans and other training materials, this taxonomy includes all of the terminal performance behaviors and corresponding sub-skills required to become and function as a balanced, self-determined person who manages the problems of everyday life…

  9. Are the Kids Alright? What's Shaping the Attitudes, Values and Behaviour of our Young People? = Les enfants se portent-ils bien? Qu'est-ce qui faconne les attitudes, les valeurs et le comportement de nos jeunes?

    ERIC Educational Resources Information Center

    Theilheimer, Ish, Ed.

    1992-01-01

    This theme issue explores the behavior of teenagers. "Are the Kids Alright?" (Ish Theilheimer) develops a perspective on the subject of teen behavior, noting that a growing number of young people demonstrate discontent, alienation, aggression, violence, and antisocial behavior, and that a growing underclass of children is likely to fail. The…

  10. Crystal structure of 1,1,2,2-tetra­methyl-1,2-bis­(2,3,4,5-tetra­methyl­cyclo­penta-2,4-dien-1-yl)disilane

    PubMed Central

    Godemann, Christian; Spannenberg, Anke; Beweries, Torsten

    2015-01-01

    The mol­ecular structure of the title compound, C22H38Si2, features a trans arrangement of the cyclo­penta­dienyl rings to avoid steric strain [C—Si—Si—C torsion angle = −179.0 (5)°]. The Si—Si bond length is 2.3444 (4) Å. The most notable inter­molecular inter­actions in the mol­ecular packing are C—H⋯π contacts that lead to the formation of wave-like supra­molecular chains along the b axis. PMID:26594581

  11. Crystal structure of 1,1,2,2-tetra-methyl-1,2-bis-(2,3,4,5-tetra-methyl-cyclo-penta-2,4-dien-1-yl)disilane.

    PubMed

    Godemann, Christian; Spannenberg, Anke; Beweries, Torsten

    2015-11-01

    The mol-ecular structure of the title compound, C22H38Si2, features a trans arrangement of the cyclo-penta-dienyl rings to avoid steric strain [C-Si-Si-C torsion angle = -179.0 (5)°]. The Si-Si bond length is 2.3444 (4) Å. The most notable inter-molecular inter-actions in the mol-ecular packing are C-H⋯π contacts that lead to the formation of wave-like supra-molecular chains along the b axis. PMID:26594581

  12. cyclo-Tri-μ-oxido-tris-{[(η,η)-1,2-bis-(cyclo-penta-dien-yl)-1,1,2,2-tetra-methyl-disilane]zirconium(IV)}: a trimeric disila-bridged oxidozirconocene.

    PubMed

    Arnold, Thomas; Braunschweig, Holger; Gruss, Katrin

    2011-04-01

    The title compound, [Zr(3)(C(14)H(20)Si(2))(3)O(3)], consists of three disila-bridged zirconocene units, which are connected via an oxide ligand, forming a nearly planar six-membered ring with a maximum displacement of 0.0191 (8) Å. The compound was isolated as a by-product from a mixture of [(C(5)H(4)SiMe(2))(2)ZrCl(2)] and Li[AlH(4)] in Et(2)O. PMID:21753927

  13. A purple odyssey: synthesis and structure of 3-amino-4-hy­droxy-6-oxo­cyclo­hexa-2,4-dien-1-iminium chloride monohydrate

    PubMed Central

    Plater, M. John; Harrison, William T. A.

    2016-01-01

    In the cation of the title hydrated mol­ecular salt, C6H7N2O2 +·Cl−·H2O, the six-membered ring shows unequal bond lengths consistent with delocalization of electrons over two separate 6π systems with single bonds between them. In the crystal, the components are linked by N—H⋯Cl, N—H⋯O, O—H⋯Cl and O—H⋯O hydrogen bonds, generating double layers propagating in (100). PMID:27307999

  14. 5,5,7,12,14,14-Hexamethyl-1,8-diaza-4,11-diazo­niacyclo­tetra­deca-4,11-diene dichloride trihydrate

    PubMed Central

    Ismail, Wafiuddin; Yamin, Bohari M.; Daran, Jean-Claude

    2012-01-01

    In the title compound, C16H34N4 2+·2Cl−·3H2O, the two protonated N atoms in the macrocyclic ring of the dication are located at diagonally opposite positions. There are two intramolecular N—H⋯N hydrogen bonds in the cation. The crystal structure features O—H⋯Cl, O—H⋯O, C—H⋯Cl and N—H⋯Cl hydrogen bonds. PMID:22590349

  15. (2Z,4E)-1-(5-Fluoro-2-hy­droxy­phen­yl)-5-(4-fluoro­phen­yl)-3-hy­droxy­penta-2,4-dien-1-one

    PubMed Central

    Chen, Jing-Wei; He, Zhuo; Wu, Zhen; Fang, Mei-Juan; Fang, Hua

    2014-01-01

    In the title mol­ecule, C17H12F2O3, the dihedral angle between the benzene rings is 8.6 (2)°. In the crystal, two pairs of O—H⋯O hydrogen bonds connect the mol­ecules into inversion dimers. In addition, weak C—H⋯F hydrogen bonds link the dimers into a two-dimensional network parallel to (10-4). The carbonyl O atom is an acceptor for two weak intra­molecular hydrogen bonds. PMID:24527017

  16. Ameliorative Effects of Operculina turpethum and its Isolated Stigma-5,22dien-3-o-β-D-glucopyranoside on the Hematological Parameters of Male Mice Exposed to N-Nitrosodimethylamine, a Potent Carcinogen

    PubMed Central

    Sharma, Veena; Singh, Manu

    2014-01-01

    Objectives: Enormous propensity of plants to synthesize a variety of structurally diverse bioactive compounds, has made the plant kingdom a potential source of chemical constituents with various therapeutic values, including antitumor and cytotoxic activities. Blood is a good indicator to determine the physiological and pathological status of man and animal. The objective of the present study is to determine the effect of Operculina turpethum root extract and its isolated glycoside treatment on the hematological parameters in the mice with N-Nitrosodimethylamine (NDMA) induced cancer. Materials and Methods: The body weights of the animals were recorded before and after the experiment. Non-coagulated blood was tested for total erythrocyte count, total leukocyte count, hemoglobin, differential leukocyte count (DLC) and for other blood indices. Results: A significant (P < 0.01), (P < 0.001) recovery of the red blood cell and white blood cell counts, packed cell volume and hemoglobin content in the host after 21 day treatment was shown. Conclusion: These results show that the extract of Operculina turpethum is relatively safe following oral administration and have possible stimulatory effect on red blood cell production and there was dose dependent therapeutic effect. PMID:24748732

  17. Hexamethyl 13,14-dioxapenta­cyclo­[8.2.1.14,7.02,9.03,8]tetra­deca-5,11-diene-1,4,5,6,11,12-hexa­carboxyl­ate

    PubMed Central

    Lough, Alan J.; Jack, Kelsey; Tam, William

    2012-01-01

    In the title compound, C24H24O14, the stereochemistry at the cyclo­butane ring is cis-anti-cis and the –COOMe groups in the bicyclic rings are syn to each other. The mol­ecule lies on a twofold rotation axis. In the crystal, weak C—H⋯O hydrogen bonds connect mol­ecules into chains along [001], forming R 2 2(10) rings. PMID:23125745

  18. Addition polymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and Bis-dienes. 2: Evidence for thermal dehydration occurring in the cure process

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Olshavsky, Michael A.; Meador, Michael A.; Ahn, Myong-Ku

    1988-01-01

    Diels-Alder cycloaddition copolymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and anthracene end-capped polyimide oligomers appear, by thermogravimetric analysis (TGA), to undergo dehydration at elevated temperatures. This would produce thermally stable pentiptycene units along the polymer backbone, and render the polymers incapable of unzipping through a retro-Diels-Alder pathway. High resolution solid 13C nuclear magnetic resonance (NMR) of one formulation of the polymer system before and after heating at elevated temperatures, shows this to indeed be the case. NMR spectra of solid samples of the polymer before and after heating correlated well with those of the parent pentiptycene model compound before and after acid-catalyzed dehydration. Isothermal gravimetric analyses and viscosities of the polymer before and after heat treatment support dehydration as a mechanism for the cure reaction.

  19. {2-[(η5-Cyclo­penta­dien­yl)diphenyl­meth­yl]-1H-imidazolido-κN}bis­(N,N-diethyl­amido)­titanium(IV)

    PubMed Central

    Cai, Xianfeng; Xu, Yingying; Nie, Wanli; Borzov, Maxim V.

    2011-01-01

    The chemically achiral title mol­ecule, [Ti(C4H10N)2(C21H16N2)], crystallizes in the chiral space group P21. All three N atoms coordinating to the TiIV atom adopt planar environments [sums of valence angles = 359.5 (6), 360.0 (7) and 360.0 (6)°], which is indicative of pπ–dπ donation from all of these N atoms to the metal and, thus, of the formal 18 e− nature of the complex. The overall coordination about the TiIV atom is distorted tetra­hedral, assuming the cyclo­penta­dienyl ring occupies one coordination site. The Ti—Nimidazole amide-type bond is longer by approximately 0.16 Å than the other two Ti—Namide bonds. PMID:21754286

  20. (μ3-Hydrido)[μ3-2-(tri-methyl-sil-yl)ethyl-idyne-κ(3) C (1):C (1):C (1)]tetra-kis-[(η(5)-cyclo-penta-dien-yl)cobalt(II)].

    PubMed

    Haehnel, Martin; Spannenberg, Anke; Rosenthal, Uwe

    2013-11-01

    In the title compound, [Co4(C5H5)4(μ3-CCH2SiMe3)(μ3-H)], the Co atoms form a distorted tetra-hedron with the ethyl-idyne moiety bridging three of the Co atoms as well as the hydrido ligand also bridging three of the Co atoms. The Co-Co bond lengths in the Co4 tetrahedron vary from 2.3844 (4) to 2.4608 (4) Å. Each Co atom is additionally η(5)-bonded to a cyclopentadienyl (Cp) anion. PMID:24454164

  1. Practical synthesis of [n]cycloparaphenylenes (n = 5, 7-12) by H2SnCl4-mediated aromatization of 1,4-dihydroxycyclo-2,5-diene precursors.

    PubMed

    Patel, Vijay Kumar; Kayahara, Eiichi; Yamago, Shigeru

    2015-04-01

    Cyclic precursors of cycloparaphenylenes (CPPs) containing 1,4-dihydroxy-2,5-cyclohexadien-1,4-diyl units are prepared by modifying a synthetic method developed by Jasti and co-workers for the synthesis of corresponding 1,4-dimethoxy derivatives. Reductive aromatization of the diyl moieties by SnCl2/2 HCl takes place under mild conditions and affords the CPPs in good yields, incorporating 5 or 7-12 phenylene units. Highly strained [5]CPP is synthesized in greater than 0.3 g scale. (119)Sn NMR spectroscopy clarifies the in situ formation of an ate complex, H2SnCl4, upon mixing a 2:1 ratio of HCl and SnCl2, which serves as a highly active reducing agent under nearly neutral conditions. When more than 2 equivalents of HCl, in relation to SnCl2, are used, acid-catalyzed decomposition of the CPP precursors takes place. The stoichiometry of HCl and SnCl2 is critical in achieving the desired aromatization reaction of highly strained CPP precursors. PMID:25753916

  2. Transmetalation from B to Rh in the course of the catalytic asymmetric 1,4-addition reaction of phenylboronic acid to enones: a computational comparison of diphosphane and diene ligands.

    PubMed

    Li, You-Gui; He, Gang; Qin, Hua-Li; Kantchev, Eric Assen B

    2015-02-14

    Transmetalation is a key elementary reaction of many important catalytic reactions. Among these, 1,4-addition of arylboronic acids to organic acceptors such as α,β-unsaturated ketones has emerged as one of the most important methods for asymmetric C-C bond formation. A key intermediate for the B-to-Rh transfer arising from quaternization on a boronic acid by a Rh-bound hydroxide (the active catalyst) has been proposed. Herein, DFT calculations (IEFPCM/PBE0/DGDZVP level of theory) establish the viability of this proposal, and characterize the associated pathways. The delivery of phenylboronic acid in the orientation suited for the B-to-Rh transfer from the very beginning is energetically preferable, and occurs with expulsion of Rh-coordinated water molecules. For the bulkier binap ligand, the barriers are higher (particularly for the phenylboronic acid activation step) due to a less favourable entropy term to the free energy, in accordance with the experimentally observed slower transmetalation rate. PMID:25422851

  3. Un mode de découverte inhabituel d'hyperparathyroïdie primaire: fractures multiples sur tumeurs brunes secondaires à un adénome parathyroïdien ectopique médiastinal

    PubMed Central

    Yassine, Asmaa; Guerboub, Ahmed Anas; Arsalane, Adil; Biyi, Abdelhamid; Moussaoui, Souad El; Belmejdoub, Ghizlaine

    2015-01-01

    La tumeur brune est une entité clinique bénigne apparaissant comme une manifestation squelettique rare de l'hyperparathyroïdie primaire. Il s'agit d'une cause inhabituelle de fractures pathologiques. Nous rapportons ici le cas clinique d'un patient âgé de 20 ans chez qui l'hyperparathyroïdie primitive a été découverte devant des tumeurs brunes multiples. PMID:26966486

  4. Crystal structure of azido­(η5-cyclo­penta­dien­yl)bis­(tri­phenyl­phosphane-κP)ruthenium(II) di­chloro­methane hemisolvate

    PubMed Central

    Hernández-Calva, Adriana; Meléndez-Balbuena, Lidia; Arroyo, Maribel; Ramírez-Monroy, Armando

    2014-01-01

    The title solvated complex, [Ru(η5-C5H5)(N3){P(C6H5)3}2]·0.5CH2Cl2, displays a typical piano-stool geometry about the RuII atom. The bond lengths and angles of the cyclo­penta­dienyl and phosphane ligands are very similar to that of the unsolvated complex [Taqui Khan et al. (1994 ▶). Acta Cryst. C50, 502–504]. The azide anion displays similar N—N distances of 1.173 (3) and 1.156 (3) Å and has an N—N—Ru angle of 119.20 (15)°, indicating a greater contribution of the canonical form Ru—N=N(+)=N(-) for the bonding situation. An intra­molecular C—H⋯N hydrogen-bonding inter­action between one ortho H atom of a phosphane ligand and the N atom coordinating to the metal is observed. A similar inter­molecular inter­action is observed between a meta H atom of a phosphane ligand and the terminal azide N atom of a neighbouring complex. Finally, two C—H⋯N inter­actions exists between the H atoms of the di­chloro­methane solvent mol­ecule and the terminal N atom of two azide anions. The solvent mol­ecule is located about a twofold rotation axis and shows disorder of the Cl atoms with an occupancy ratio of 0.62 (3):0.38 (3). PMID:25484673

  5. (Glycol-κ2 O,O′)nitros­yl(η5-penta­methyl­cyclo­penta­dien­yl)ruthenium(II) bis­(tri­fluoro­methane­sulfonate)

    PubMed Central

    Munie, Semeret; Larsen, Anna; Gembicky, Milan

    2008-01-01

    The title compound, [Ru(C10H15)(NO)(HOCH2CH2OH)](CF3SO3)2, possesses a three-legged piano-stool geometry around the Ru atom, with an average Ru—O distance of 2.120 (6) Å and an Ru—N—O angle of 159.45 (14)°. The ethyl­eneglycol ligand forms a non-planar metallacyclic ring by chelating the Ru atom via the O atoms. The O⋯O distances of 2.554 (2) and 2.568 (2) Å are indicative of hydrogen bonding between coordinated ethyl­eneglycol and outer-sphere trifluoro­methane­sulfonate fragments. The crystal packing is stabilized by ionic forces and several CH3⋯·F (2.585 and 2.640 Å) and CH3⋯O inter­actions (2.391, 2.678, 2.694 and 2.699 Å) between the penta­methyl­cyclo­penta­dienyl ligand and trifluoro­methane­sulfonate anion. There is noticeable short inter­molecular contact [2.9039 (16) Å], between an O atom of the SO3 group and a C atom of the penta­methyl­cyclo­penta­dienyl ligand. PMID:21201270

  6. (3-Chloro­phen­yl){2-eth­oxy-5-[(Z)-hydroxy(phen­yl)methyl­idene]cyclo­penta-1,3-dien-1-yl}methanone

    PubMed Central

    Tinţaş, Mihaela-Liliana; Varga, Richard A.; Grosu, Ion; Bogdan, Elena

    2012-01-01

    The title compound, C21H17ClO3, which crystallizes as one of two possible oxo/hy­droxy-fulvene prototropic tautomers, possesses a strong intra­molecular O—H⋯O hydrogen bond that closes a seven-membered ring. The dihedral angles between the central five-membered ring and two pendant rings are 55.05 (9) and 44.51 (10)°. The crystal packing is characterized by weak inter­molecular C—H⋯O inter­actions between an H atom of the oxymethyl­ene unit and the carbonyl group of an adjacent mol­ecule, resulting in formation of chains of mol­ecules along the a axis. PMID:22346947

  7. Bis(μ-2-tert-butyl-phenyl-imido-1:2κN:N)chlorido-2κCl-(diethyl ether-1κO)(2η-penta-methyl-cyclo-penta-dien-yl)lithiumtantalum(V).

    PubMed

    Cole, Jacqueline M; Chan, Michael C W; Gibson, Vernon C; Howard, Judith A K

    2011-06-01

    In the title compound, [LiTa(C(10)H(15))(C(10)H(13)N)(2)Cl(C(4)H(10)O)], the Ta(V) atom is coordinated by a η(5)-penta-methyl-cyclo-penta-dienyl (Cp*) ligand, a chloride ion and two N-bonded 2-tert-butyl-phenyl-imide dianions. With respect to the two N atoms, the chloride ion and the centroid of the Cp* ring, the tantalum coordination geometry is approximately tetra-hedral. The lithium cation is bonded to both the 2-tert-butyl-phenyl-imide dianions and also a diethyl ether mol-ecule, in an approximate trigonal planar arrangement. The Ta⋯Li separation is 2.681 (15) Å. In the crystal, a weak C-H⋯Cl inter-action links the mol-ecules. When compared to the 2,6-diisopropyl-phenyl-imide analogue ('the Wigley derivative') of the title compound, the two structures are conformationally matched with an overall r.m.s. difference of 0.461Å. PMID:21754594

  8. The Structure and Assembly Mechanism of a Novel Three-Stranded Tubulin Filament that Centers Phage DNA

    PubMed Central

    Zehr, Elena A.; Kraemer, James A.; Erb, Marcella L.; Coker, Joanna K.C.; Montabana, Elizabeth A.; Pogliano, Joe; Agard, David A.

    2014-01-01

    SUMMARY Tubulins are a universally conserved protein superfamily that carry out diverse biological roles by assembling filaments with very different architectures. The underlying basis of this structural diversity is poorly understood. Here, we determine a 7.1 Å cryo-EM reconstruction of the bacteriophage-encoded PhuZ filament and provide molecular-level insight into its cooperative assembly mechanism. The PhuZ family of tubulins is required to actively center the phage within infected host cells, facilitating efficient phage replication. Our reconstruction and derived model reveal the first example of a three-stranded tubulin filament. We show that the elongated C-terminal tail simultaneously stabilizes both longitudinal and lateral interactions, which in turn define filament architecture. Identified interaction surfaces are conserved within the PhuZ family, and their mutagenesis compromises polymerization in vitro and in vivo. Combining kinetic modeling of PhuZ filament assembly and structural data we suggest a common filament structure and assembly mechanism for the PhuZ family of tubulins. PMID:24631461

  9. Family health consequences of modernisation programmes in Black Thai communities.

    PubMed

    Oosterhoff, Pauline; White, Joanna; Nguyen, Thi Huong

    2011-12-01

    Southeast Asian governments implement ambitious programmes to reduce population growth and maternal mortality in areas with large minority ethnic populations. Although some of these programmes introduce new social and health practices that meet their broader aims, they may pay inadequate attention to the protective and medically beneficial aspects of traditional practices. This study examined the decline of temporary matrilocality (zu kuay) among the Black Thai in Dien Bien, Vietnam, as a response to policies adopted under the government programme of Doi Moi ('modernisation'). The patrilocal, patrilinear cultural norms of the majority ethnic Kinh people were promoted and zu kuay discouraged at a time when heroin availability increased dramatically but harm reduction programmes were not yet in place. This historical coincidence appears to have heightened certain Thai women's vulnerability to marriages with HIV-positive injecting drug users. Policies and guidelines on marriage and reproductive health should take into account the role of minority ethnic traditions, as well as local health-seeking practices, in order not only to improve reproductive programmes but also to reduce HIV vulnerability. PMID:21491273

  10. Trichinella infection in wild boars and synanthropic rats in northwest Vietnam.

    PubMed

    Thi, N Vu; Nguyen, V D; Praet, N; Claes, L; Gabriël, S; Huyen, N T; Dorny, P

    2014-02-24

    Trichinellosis is an emerging parasitic zoonosis in North Vietnam. In this survey, hunted and farm-bred wild boars as well as synanthropic rats were sampled in two provinces of northwest Vietnam where outbreaks of trichinellosis have recently occurred. Evidence of Trichinella infection was studied by parasitological, serological and molecular methods. The results showed relatively low prevalence of Trichinella spiralis in hunted wild boars (2/62 (3.2%; 95% CI: 0.8- 4.8)) and rats (23/820 (2.8%; 95% CI: 13.7-32.3)). Parasite burdens in the muscle tissues were between 0.1 and 0.03 larvae/g, and 0.1 and 7 larvae/g in wild boars and rats, respectively. Seroprevalence in farm-bred wild boars was negative. The findings of Trichinella-infected rats in 7 of the 20 districts of Dien Bien and Son La provinces suggest that the parasite is circulating in these regions. These results indicate that the local population and health centers should be made aware of the risks of eating raw or undercooked meat dishes prepared from wild animals. PMID:24360291