- Nitrile biotransformation for highly enantioselective synthesis of 3-substituted 2,2-dimethylcyclopropanecarboxylic acids and amides
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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.
- Wang, Mei-Xiang,Feng, Guo-Qiang
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p. 621 - 624
(2007/10/03)
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- Search for Routes of Synthesis of Permethrin and Chloropermethrin Starting from Halogen-containing Alkenoic Acids
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Promising procedures were developed for the synthesis of permethrin and I-chloropermethrin starting from acid chloride, nitrile, and esters of 3,3-dimethyl-2,2,4,6,6-pentachloro-5-alkenoic acid and 3,3-dimethyl-2,2,6,6-tetrachloro-5-alken-4-olide, which were prepared by adding derivatives of trichloroacetic acid to 1,1-dichloro-4-methyl-1,3-pentadiene in the presence of catalytic amounts of monovalent copper ions and amine.
- Badanyan,Stepanyan,Mikaelyan,Ovivyan,Panosyan
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- Synthesis of ethyl (+/-)-cis-3-(2,2-dihalogenovinyl)-2,2-dimethylcyclopropanecarboxylate
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The two (+/-) cis pyrethroid ethyl esters 2a,b have been synthesized.These esters are obtained via stereoselective ScN' cyclization of 3b to 5b.Desulfonylation of 5b with retention of configuration at low temperature (Na/Hg, -30 deg C) affords (+/-)-cis-chrysanthemonitrile 6.This nitrile is converted into cis aldehyde 7 which by Wittig reaction provides pyrethroid nitriles 8a and 8b, respectively.Finally hydrolysis of the nitrile group gives the esters 2a and 2b in 30percent overall yield from 3b.
- Genet, J. P.,Denis, A.,Charbonnier, F.
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p. 793 - 796
(2007/10/02)
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- Process for the preparation of 1,1-dichloroalkenes
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A process for the preparation of a 1,1-dichloroalkene of the formula STR1 in which R1 is hydrogen or an optionally substituted alkyl, alkenyl, alkynyl, aralkyl or aryl radical, and R2 is an optionally substituted alkyl, alkenyl, alkynyl, aralkyl, aralkenyl or aryl radical, or cycloalkyl which is optionally substituted by halogen, alkyl, alkanoyl, carbamoyl, cyano or phenyl, or R1 and R2 together form a hydrocarbon chain which is optionally branched and/or optionally contains a fused benzene ring, comprising reacting an aldehyde or ketone of the formula STR2 with a dichloromethane-phosphonic acid ester of the formula STR3 in which R3 each independently is alkyl or phenyl or the two radicals R3 together are alkanediyl, in the presence of a base at a temperature between about -50° and +50° C. Preferably either the base is metered into a mixture of the aldehyde or ketone and phosphonic acid ester or the ester is added to a mixture of the base and aldehyde or ketone.
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- Preparation of cyano-substituted cyclopropane derivatives
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A novel process is disclosed for the preparation of cyano-substituted cyclopropane derivatives of the following general formula: STR1 wherein R1, R2 and Hal have the meanings given in the description. The process comprises the steps of cyclizing and dehydrohalogenating, in the presence of a base, a 4,6,6,6-tetrahalo-2-cyano-3,3-dialkylhexanoic acid or an alkyl ester thereof, followed by thermal decarboxylation of the resulting cyclized and dehydrohalogenated product. Under selected conditions cyclization, dehydrohalogenation and decarboxylation occur simultaneously in one reaction zone. The resulting cyano-substituted cyclopropane derivatives are useful as intermediates in the production of insecticidally active compounds.
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- 1-Acetyl or 1-cyano-2(2,2-dichlorovinyl)-3,3-dimethyl cyclopropane
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1-acetyl or 1-cyano-2(2,2-dichlorovinyl)-3,3-dimethylcyclopropane. These compounds are useful intermediates.
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