Photoinduced Synthesis of Polycyclic γ‐Sultines by a Radical‐Polar Crossover Cyclization

Described herein is a visible light-mediated radical addition/SO2 insertion/anionic cyclization of benzo-fused homoallylic tosylates, allowing access to a diverse array of otherwise challenging-to-access fluoromethylated polycyclic ?-sultines with two adjacent tetrasubstituted carbon stereocenters in 49-95% yields, which can be further readily functionalized towards bulky two adjacent tetrasubstituted carbon-containing benzo-fused ?-sultone and mercaptoalkanol. Sodium fluoroalkanesulfinates were utilized as bifunctionalization reagents for both fluoromethyl groups and SO2. The cyclization proceeds through a stepwise photoinduced radical addition followed by an intramolecular 5-exo-tet anionic substitution cyclization after SO2 insertion.