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Biotransformations of various functionalized racemic nitriles catalyzed by
Rhodococcus erythropolis AJ270,a nitrile hydratase/amidase-containing microbial whole-cell catalyst, were studied. While the nitrilehydratase exhibits high catalytic efficiency but very low enantioselectivity against almost all nitrilesubstrates examined, the amidase is very sensitive toward the structure of the amides. The release of thesteric crowdedness around the stereocenter of the substrates and the introduction of an unsaturated carbon-carbon bond into the substrates led to the significant acceleration of the reaction rate and the dramaticenhancement of the enantioselectivity. Nitrile biotransformations provide a unique and high-yieldingsynthetic route to highly enantiopure carboxylic acids and amides functionalized with an allyl, propargyl,allenyl, or vinyl group. The synthetic applications have been demonstrated by the synthesis of enantiopureheterocyclic compounds including iodoenol
-lactone,
-lactam, and 3-allyl-1-phenyl-3,4-dihydro-1
H-quinolin-2-one derivatives.
