2259-14-5Relevant academic research and scientific papers
Identification of the catalytic residues of carboxylesterase from arthrobacter globiformis by diisopropyl fluorophosphate-labeling and site-directed mutagenesis
Nishizawa, Masako,Yabusaki, Yoshiyasu,Kanaoka, Masaharu
, p. 89 - 94 (2011)
The role of amino acid residues in the enzymatic activity of carboxylesterase from Arthrobacter globiformis was analyzed by diisopropyl fluorophosphate (DFP) labeling and site-directed mutagenesis. The electrospray ionization mass spectrometric (ESI-MS) analysis of the esterase, covalently labeled by DFP, showed stoichiometric incorporation of the inhibitor into the enzyme. The further comparison of endopeptidase-digested fragments between native and DFP-labeled esterase by fast atom bombardment mass spectrometric (FAB-MS) analysis as well as site-directed mutagenesis indicated that Ser59 in the consensus sequence Ser-X-X-Lys, which is conserved exclusively in penicillin-binding proteins and some esterases, served as a catalytic nucleophile. In addition, the results obtained from analysis of the mutants at position 62 suggested the importance of the basic amino acid side chain at this position, and suggested the significance of this residue acting directly as a general base rather than its involvement in the maintenance of the optimum hydrogenbonding network at the active site.
Enzyme catalysed kinetic resolution of racemic 2,2-dimethyl-3-(2,2- disubstituted vinyl) cyclopropane carboxylic acids anchored on polymer supports
Nanda,Bhaskar Rao,Yadav
, p. 5905 - 5908 (1999)
Kinetic resolution of trans-substituted cyclopropane carboxylic acids anchored on a solid support by lipase is described.
Total Syntheses of All Six Chiral Natural Pyrethrins: Accurate Determination of the Physical Properties, Their Insecticidal Activities, and Evaluation of Synthetic Methods
Ashida, Yuichiro,Kawamoto, Momoyo,Matsuo, Noritada,Moriyama, Mizuki,Tanabe, Yoo
, p. 2984 - 2999 (2020/03/24)
Chiral total syntheses of all six insecticidal natural pyrethrins (three pyrethrin I and three pyrethrin II compounds) contained in the chrysanthemum (pyrethrum) flower were performed. Three common alcohol components [(S)-cinerolone, (S)-jasmololone, and (S)-pyrethrolone] were synthesized: (i) straightforward Sonogashira-type cross-couplings using available (S)-4-hydroxy-3-methyl-2-(2-propynyl)cyclopent-2-en-1-ones (the prallethrin alcohol) for (S)-cinerolone (overall 52% yield, 98% ee) and (S)-pyrethrolone (overall 54% yield, 98% ee) and (ii) traditional decarboxylative-aldol condensation and lipase-catalyzed optical resolution for (S)-jasmololone (overall 16% yield, 96% ee). Two counter acid segments [(1R,3R)-chrysanthemic acid (A) and (1R,3R)-second chrysanthemic acid precursor (B)] were prepared: (i) C(1) epimerization of ethyl (±)-chrysanthemates and optical resolution using (S)-naphthylethylamine to afford A (96% ee) and (ii) concise derivatization of A to B (96% ee). All six pyrethrin esters (cinerin I/II, jasmolin I/II, and pyrethrin I/II) were successfully synthesized utilizing an accessible esterification reagent (TsCl/N-methylimidazole). To investigate the stereostructure-activity relationship, all four chiral stereoisomers of cinerin I were synthesized. Three alternative syntheses of (±)-jasmololone were investigated (methods utilizing Piancatelli rearrangement, furan transformation, and 1-nitropropene transformation). Insecticidal activity assay (KD50 and IC50) against the common mosquito (Culex pipiens pallens) revealed that (i) pyrethrin I > pyrethrin II, (ii) pyrethrin I (II) > cinerin I (II) ? jasmolin I (II), and (iii) "natural" cinerin I ? three "unnatural" cinerin I compounds (apparent chiral discrimination).
Lewis Acid Catalyzed Enantioselective Photochemical Rearrangements on the Singlet Potential Energy Surface
Leverenz, Malte,Merten, Christian,Dreuw, Andreas,Bach, Thorsten
supporting information, p. 20053 - 20057 (2019/12/30)
The oxadi-methane rearrangement of 2,4-cyclohexadienones to bicyclic ketones was found to proceed with high enantioselectivity (92-97% ee) in the presence of catalytic amounts of a chiral Lewis acid (15 examples, 52-80% yield). A notable feature of the transformation is the fact that it proceeds on the singlet hypersurface and that no triplet intermediates are involved. Rapid racemic background reactions were therefore avoided, and the catalyst loading could be kept low (10 mol %). Computational studies suggest that the enantioselectivity is determined within a Lewis acid bound singlet intermediate via a conical intersection. The utility of the method was demonstrated by a concise synthesis of the natural product trans-chrysanthemic acid.
Cyclopropanation of Terminal Alkenes through Sequential Atom-Transfer Radical Addition/1,3-Elimination
Tappin, Nicholas D. C.,Michalska, Weronika,Rohrbach, Simon,Renaud, Philippe
supporting information, p. 14240 - 14244 (2019/08/26)
An operationally simple method to affect an atom-transfer radical addition of commercially available ICH2Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in a one-pot process into the corresponding cyclopropane upon treatment with a fluoride source. This method is highly selective for the cyclopropanation of unactivated terminal alkenes over non-terminal alkenes and electron-deficient alkenes. Due to the mildness of the procedure, a wide range of functional groups such as esters, amides, alcohols, ketones, and vinylic cyclopropanes are well tolerated.
Syntheses of racemic and scalemic cis-chrysanthemic acid from β,γ-unsaturated cyclohexanol
Krief, Alain,Jeanmart, Stéphane,Gondal, Humaira Y.,Kremer, Adrian
, p. 2123 - 2167 (2013/02/23)
2,2,5,5-Tetramethylcyclohexane-1,3-dione is a valuable starting-material precursor of cis-chrysanthemic acid. The (1S)-stereoisomer is a precursor of pyrethrin I, the most active natural insecticide from Chrysanthemum cinerariifolium, whereas the (1R)-stereoisomer is efficiently transformed to deltamethrin, the most active commercially available pyrethroid insecticide. Several intermediates have been identified and used with variable success for that purpose.
Unprecedented dual reactivity of anhydrous potassium hydroxide in cascade cyclopropannelation/Haller-Bauer-scission/Grob-fragmentation reactions
Krief, Alain,Kremer, Adrian
body text, p. 4306 - 4309 (2010/09/20)
We report an unprecedented type of reactivity of 'anhydrous potassium hydroxide' ('APH') in which it plays, over a large variety of related educts, sequentially the role of base and nucleophile. Some insight into the structure of reactive species as well as comparative reactivity of related reagents prepared by fusion of commercially available potassium hydroxide or by adding stoichiometric amount of water to potassium hydride is provided.
A practical method for O-acylation of N -hydroxythiazole-2(3 H)-thiones
Schur, Christine,Gross, Andreas,Hartung, Jens
experimental part, p. 538 - 542 (2010/06/13)
O-Acylation of 4- and 4,5-substituted N-hydroxythiazole-2(3H)-thiones occurred in solutions of acetone upon treatment with solid K2CO3 and a variety of neat acyl chlorides (primary, secondary, and tertiary alkyl, aryl; 60-87% yield; ～10 g scale).
PROCESS FOR OBTAINING ENANTIOMERS OF CHRYSANTHEMIC ACID
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Page/Page column 15-17, (2008/06/13)
A new process is described, easy to perform on industrial scale, with high yield, for obtaining enantiomers of chrysanthemic acid starting from mixtures containing them. The process involves reacting said mixtures with enantiomers of 2- dimethylamino-1-phenyl-1 ,3-propanediol (DMPP) and 2-dimethylamino-1-[4- (methylthio)phenyl]propane-1 ,3-diol (MTDP) as chiral selectors. The invention includes salts of chrysanthemic acid with the aforesaid chiral selectors as process intermediates. The process allows operation in a single solvent rather than in solvent mixtures difficult to recover and reuse, and the final crystallization product does not incorporate molecules of solvent. The bases used are then recovered and reused in subsequent separations.
Nitrile biotransformation for highly enantioselective synthesis of 3-substituted 2,2-dimethylcyclopropanecarboxylic acids and amides
Wang, Mei-Xiang,Feng, Guo-Qiang
, p. 621 - 624 (2007/10/03)
Biotransformations of differently configured 2,2-dimethyl-3-substitued-cyclopropanecarbonitriles were studied using a nitrile hydratase/amidase-containing Rhodococcus sp. AJ270 whole-cell catalyst under very mild conditions. Although all of the cis-3-aryl-2,2-dimethylcyclopropanecarbonitriles appeared inert toward the biocatalyst, a number of racemic trans-isomers efficiently underwent a highly enantioselective hydrolysis to produce (+)-(1R,3R)-3-aryl-2,2-dimethylcyclopropanecarboxylic acids and (-)-(1S,3S)-3-aryl-2,2-dimethylcyclopropanecarboxamides in high yields with excellent enantiomeric excesses in most cases. The overall enantioselectivity of the biotransformations of nitriles originated from the combined effects of 1R-enantioselective nitrile hydratase and amidase, with the later being a dominant factor. The influence of the substrates on both reaction efficiency and enantioselectivity was discussed in terms of steric and electronic effects. Coupled with chemical transformations, biotransformations of nitriles provided convenient syntheses of optically pure geminally dimethyl-substituted cyclopropanecarboxylic acids and amides, including chrysanthemic acids, in both enantiomeric forms.
