| Abstract
| - 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 numberof racemic trans-isomers efficiently underwent a highlyenantioselective hydrolysis to produce (+)-(1R,3R)-3-aryl-2,2-dimethylcyclopropanecarboxylic acids and (−)-(1S,3S)-3-aryl-2,2-dimethylcyclopropanecarboxamides in high yieldswith excellent enantiomeric excesses in most cases. Theoverall enantioselectivity of the biotransformations of nitrilesoriginated from the combined effects of 1R-enantioselectivenitrile hydratase and amidase, with the later being adominant factor. The influence of the substrates on bothreaction efficiency and enantioselectivity was discussed interms of steric and electronic effects. Coupled with chemicaltransformations, biotransformations of nitriles providedconvenient syntheses of optically pure geminally dimethyl-substituted cyclopropanecarboxylic acids and amides, including chrysanthemic acids, in both enantiomeric forms.
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