Synthesis of Chiral Sulfoxides by A Cyclic Oxidation?Reduction Multi?Enzymatic Cascade Biocatalysis
Optically pure sulfoxides are valuable organosulfur compounds extensively employed in medicinal and organic synthesis. In this study, we present a biocatalytic oxidation?reduction cascade system designed for the preparation of enantiopure sulfoxides. The system involves the cooperation of a low?enantioselective chimeric oxidase SMO (styrene monooxygenase) with a high?enantioselective reductase MsrA (methionine sulfoxide reductase A), facilitating “non?selective oxidation and selective reduction” cycles for prochiral sulfide oxidation. The regeneration of requisite cofactors for MsrA and SMO was achieved via a cascade catalysis process involving three auxiliary enzymes, sustained by cost?effective D?glucose. Under the optimal reaction conditions, a series of heteroaryl alkyl, aryl alkyl and dialkyl sulfoxides in R configuration were synthesized through this “one?pot, one step” cascade reaction. The obtained compounds exhibited high yields of >90% and demonstrated enantiomeric excess (ee) values exceeding 90%. This study represents an unconventional and efficient biocatalytic way in utilizing the low?enantioselective oxidase for the synthesis of enantiopure sulfoxides.