Monooxygenase-catalyzed Baeyer–Villiger oxidations: CHMO versus CPMO

Cyclopentanone monooxygenase (CPMO) from Comamonas sp. NCIMB 9872 expressed in E. coli was evaluated as a potential new bioreagent for Baeyer–Villiger oxidations of 4-alkoxy- and halo-substituted cyclohexanones (10 examples). The results were compared with those obtained in oxidations catalyzed by an engineered E. coli strain expressing cyclohexanone monooxygenase (CHMO) from Acinetobacter sp. CPMO was found to have modest to good stereoselectivity and broader substrate acceptability than CHMO. The stereoselectivities of the two enzymes were generally opposite. It appears, therefore, that the two engineered strains can be useful and complementary reagents for enantioselective Baeyer–Villiger oxidations of certain prochiral ketones.