Enzymatic Synthesis of Novel Chiral Sulfoxides Employing Baeyer-Villiger Monooxygenases

Optically active sulfoxides are compounds of high interest in organic chemistry. Herein, we report the preparation of a set of chiral heteroaryl alkyl, cyclohexyl alkyl, and alkyl alkyl sulfoxides by using enantioselective sulfoxidation reactions employing three Baeyer-Villiger monooxygenases (BVMOs). Careful selection of the reaction conditions, starting sulfide, and biocatalyst can be used to achieve good to excellent enantiomeric excess values. Thus, valuable chiral synthons can be obtained by performing the reactions under mild and environmentally friendly conditions. The most promising bio-transformations that employ a BVMO cell-free extract preparation have been developed on a 250-mg scale to give the chiral sulfoxides in high yields in most of the reactions.