Highly efficient and enantioselective biotransformations of β-lactam carbonitriles and carboxamides and their synthetic applications.

Catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase and amidase containing microbial whole cell catalyst, a number of racemic 1-arylmethyl- and 1-allyl-4-oxoazetidine-2-carbonitriles and carboxamides underwent efficient transformations under very mild conditions to produce enantiopure functionalized S-amide and R-acid products in excellent yields. While the nitrile hydratase showed good enzyme activity but virtually no enantioselectivity, the amidase displayed high R-enantioselectivity against almost all amide substrates tested. The synthetic applications of the resulting functionalized chiral β-lactam derivatives were demonstrated by the facile preparation of β-lactam-fused heterocyclic compounds.

Highly efficient and enantioselective biotransformations of racemic azetidine-2-carbonitriles and their synthetic applications.

Catalyzed by the Rhodococcus erythropolis AJ270 whole cell catalyst in neutral aqueous buffer at 30 degrees C, a number of racemic 1-benzylazetidine-2-carbonitriles, trans-1-benzyl-4-methylazetidine-2-carbonitrile, and 1-benzyl-2-methylazetidine-2-carbonitrile and their amide substrates underwent efficient and enantioselective biotransformations to afford the corresponding azetidine-2-carboxylic acids and their amide derivatives in excellent yields with ee up to >99.5%. The overall excellent enantioselectivity of the biocatalytic reactions stemmed from a combined effect of a very active but virtually nonenantioselective nitrile hydratase and a high R-enantioselective amidase involved in microbial whole cells.