Asymmetric Baeyer-Villiger biooxidation of alpha-substituted cyanocyclohexanones: Influence of the substituent length on regio- and enantioselectivity

Cells of Escherichia coli expressing cyclohexanone monooxygenase catalyzed a highly enantioselective Baeyer-Villiger oxidation of a-substituted cyanocyclohexanones, leading to the corresponding enantiopure caprolactones (ees > 97%). Classical kinetic resolution and regiodivergent parallel kinetic resolution patterns were observed, depending on the length of the linear chain at the alpha position. Regioselectivity was compared with that of chemical BV oxidations. Cells revealed an outstanding stability since 50% of the specific BV activity was retained after 42 days of storage, which facilitates their use in biotransformations.