Modular Assembly of Cyclic Sulfones via Radical Annulation with Unactivated Olefins

Cyclic sulfones have been recognized as valuable motifs in drug discovery, serving as conformational constraints, hydrogen‐bonding acceptors and electron‐withdrawing functionalities. Synthetic routes such as sulfide oxidation and intramolecular cyclization involving SO 2 typically require preconstructed starting materials, limiting structural diversity. Moreover, intermolecular cyclizations toward cyclic sulfones using readily available reagents such as olefins remain scarce, and divergent and modular approaches have yet to be established. Here we report direct and tunable synthesis of cyclic sulfones from radical annulation with a broad range of unactivated olefins and sulfonylmethyl bromides via photoredox catalysis. Mechanistic studies indicate that the transformation proceeds through a radical relay cyclization process initiated by addition of highly electrophilic sulfonylmethyl radical to olefins. The utility of this method is further demonstrated through concise synthesis of three bioactive molecules bearing essential cyclic sulfone architectures.