The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Günter Helmchen - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Enantiomerically Pure (-)-Wine Lactone Based on a Palladium-Catalyzed Enantioselective Allylic Substitution.
ChemInform, 2010Co-Authors: Eike J. Bergner, Günter HelmchenAbstract:The first enantioselective synthesis of enantiomerically pure (−)-wine lactone, (−)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an Organocopper Compound and by enolate alkylation gave lactone (−)-1a in 43% overall yield from (+)-7.
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Synthesis of Enantiomerically Pure (−)-Wine Lactone Based on a Palladium-Catalyzed Enantioselective Allylic Substitution
European Journal of Organic Chemistry, 2000Co-Authors: Eike J. Bergner, Günter HelmchenAbstract:The first enantioselective synthesis of enantiomerically pure (−)-wine lactone, (−)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an Organocopper Compound and by enolate alkylation gave lactone (−)-1a in 43% overall yield from (+)-7.
Eike J. Bergner - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Enantiomerically Pure (-)-Wine Lactone Based on a Palladium-Catalyzed Enantioselective Allylic Substitution.
ChemInform, 2010Co-Authors: Eike J. Bergner, Günter HelmchenAbstract:The first enantioselective synthesis of enantiomerically pure (−)-wine lactone, (−)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an Organocopper Compound and by enolate alkylation gave lactone (−)-1a in 43% overall yield from (+)-7.
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Synthesis of Enantiomerically Pure (−)-Wine Lactone Based on a Palladium-Catalyzed Enantioselective Allylic Substitution
European Journal of Organic Chemistry, 2000Co-Authors: Eike J. Bergner, Günter HelmchenAbstract:The first enantioselective synthesis of enantiomerically pure (−)-wine lactone, (−)-1a, a fragrance constituent of various white wines, and its epimer (+)-1b, was carried out. The key steps are allylic substitution of (±)-2-cyclohexen-1-yl acetate (2) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)-7 in 47% overall yield. The diastereoselective introduction of methyl groups by SN2′-type substitution with an Organocopper Compound and by enolate alkylation gave lactone (−)-1a in 43% overall yield from (+)-7.
Shinji Toyota - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and reactivity of 2-(ethylthio) phenylcopper: A stable Organocopper Compound carrying an intramolecular sulfane ligand
Journal of Organometallic Chemistry, 1997Co-Authors: Shinji Toyota, Michinori ŌkiAbstract:Abstract An unusually stable Organocopper Compound carrying an intramolecular sulfane ligand, 2-(ethylthio)phenylcopper, was synthesized via the reaction of the corresponding organolithium with a copper(I) halide (CuX). This Compound was obtained in two forms: one is a salt-free Compound which is insoluble in ordinary solvents, the other is a soluble complex of [2-(ethylthio)phenylcopper] 2 · CuX composition. These Compounds were either hydrolyzed or underwent a coupling reaction to produce a biphenyl when heated. While these Organocoppers are less reactive towards various electrophiles than other known arylcoppers, the soluble complex gives ketones with acyl halides in low yields. The properties as well as the reactivities of the stable Organocopper Compounds are reported.
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Reaction of 2-(Alkylthiomethyl)phenyllithium with Copper(I) Halides and Structure and Properties of One of the Products—Copper(I) Complexes of 2,2′-Bis(alkylthiomethyl)biphenyl
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Shinji Toyota, Yohei Matsuda, Satoshi Nagaoka, Michinori Oki, Haruo AkashiAbstract:The title reactions did not afford the corresponding Organocopper Compound as a stable entity, but rather a dimerized biphenyl Compound (2,2′-bis(alkylthiomethyl)biphenyl), its copper(I) halide complex, and alkyl benzyl sulfide. Their yields were influenced by the kind of halides in the copper reagent. The stability and reactivity of the intermediate Organocopper Compound is discussed on the basis of the ligand-metal interactions. The copper(I) halide complex with the biphenyl which carries two sulfane ligands has a unique polymeric structure in crystals, as evidenced by X-ray analysis, whereas it dissociates into a monomeric form on dissolution in organic solvents. The properties of the complexes were examined by NMR and XPS as well.
Haruo Akashi - One of the best experts on this subject based on the ideXlab platform.
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Reaction of 2-(Alkylthiomethyl)phenyllithium with Copper(I) Halides and Structure and Properties of One of the Products—Copper(I) Complexes of 2,2′-Bis(alkylthiomethyl)biphenyl
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Shinji Toyota, Yohei Matsuda, Satoshi Nagaoka, Michinori Oki, Haruo AkashiAbstract:The title reactions did not afford the corresponding Organocopper Compound as a stable entity, but rather a dimerized biphenyl Compound (2,2′-bis(alkylthiomethyl)biphenyl), its copper(I) halide complex, and alkyl benzyl sulfide. Their yields were influenced by the kind of halides in the copper reagent. The stability and reactivity of the intermediate Organocopper Compound is discussed on the basis of the ligand-metal interactions. The copper(I) halide complex with the biphenyl which carries two sulfane ligands has a unique polymeric structure in crystals, as evidenced by X-ray analysis, whereas it dissociates into a monomeric form on dissolution in organic solvents. The properties of the complexes were examined by NMR and XPS as well.
Célia Guadalupe Tardeli De Jesus Andrade - One of the best experts on this subject based on the ideXlab platform.
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bioactive Organocopper Compound from pseudomonas aeruginosa inhibits the growth of xanthomonas citri subsp citri
Frontiers in Microbiology, 2016Co-Authors: Admilton Gonçalves De Oliveira, Caroline Santos Da Silva, Miguel Octavio Pérez Navarro, Ane Stefano Simionato, Flavia Regina Spago, Andre Riedi Barazetti, Martha Viviana Torres Cely, Cesar A Tischer, Juca Abramo Barrera San Martin, Célia Guadalupe Tardeli De Jesus AndradeAbstract:Citrus canker is a lot destructive disease of citrus species. The challenge is to find new Compounds that show strong antibiotic activity, low toxicity to plants and the environment. The objectives of the present study are (1) produce, purify and evaluate the antibiotic activity of secondary metabolites produced by induction by P. aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) study the potential for semi-purified secondary metabolites on foliar application to control citrus canker under greenhouse conditions, (3) identify the antibiotic activity in orange leaf mesophyll infected with strain 306 by electron microscopy. Two pure bioactive Compounds were isolated, Organocopper antibiotic Compound and phenazine-1-carboxamide. The phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The Organocopper antibiotic Compound showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 µg mL-1. In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d, reduced lesion formation about 97%. The concentration used was five hundred times lower than recommended commercial product of metallic copper-based. Electron microscopy showed that F3d altered the exopolysaccharide matrix and causing cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by induction by P. aeruginosa LV strain has a high potential to be used as a bioproduct to control citrus canker.