Enantioselective Trifluoromethylazidation of Styrenyl Olefins Catalyzed by an Engineered Nonheme Iron Enzyme

Abstract

Organofluorines, particularly those containing trifluoromethyl (CF₃) groups, play a critical role in medicinal chemistry. While trifluoromethylation of alkenes provides a powerful synthetic route to construct CF₃-containing compounds with broad structural and functional diversity, achieving enantioselective control in these reactions remains a formidable challenge. In this study, we engineered a nonheme iron enzyme, quercetin 2,3-dioxygenase from Bacillus subtilis (BsQueD), for the enantioselective trifluoromethylazidation of alkenes. Through directed evolution, the final variant BsQueD-CF₃ exhibited excellent enantioselectivity, with an enantiomeric ratio (e.r.) of up to 98 : 2. Preliminary mechanistic studies suggest the involvement of radical intermediates. This work expands biocatalytic organofluorine chemistry by reprogramming metalloenzymes for innovative trifluoromethylation reactions.