Photoredox-Catalyzed Allylic C-H Fluorosulfonylation of Alkenes: Accessing Allyl Sulfonyl Fluorides

Recently, the radical fluorosulfonylation of alkenes is emerging as an appealing strategy for the rapid construction of diverse sulfonyl fluorides, which are in high demand across various scientific disciplines, particularly in chemical biology and drug discovery. However, most existing methodologies have primarily focused on the vicinal difunctionalization of C=C bonds, while the selective allylic C-H fluorosulfonylation of alkenes remains an underexplored and challenging transformation. This study reported a novel and unprecedented photoredox-catalyzed protocol for direct allylic C-H fluorosulfonylation of alkenes with FABI (1-fluorosulfonyl 2-aryl benzoimidazolium triflate salts). This mild protocol exhibited excellent compatibility with various functional groups, broad substrate scope, and promising scalability, enabling convenient access to a wide range of allyl sulfonyl fluorides with exceptional regioselectivity. The synthetic robustness of this strategy was further demonstrated by the late-stage functionalization of natural products and their further ligation with other drugs via SuFEx chemistry. Experimental and theoretical analyses indicated that this transformation proceeds through a photoredox mechanism, where the selective formation of allylic sulfonyl fluorides was governed by both the dynamics and thermodynamic processes.