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

Abstract Described herein is a visible light‐mediated radical addition/SO 2 insertion/anionic cyclization of benzo‐fused homoallylic tosylates, allowing access to a diverse array of otherwise challenging‐to‐access fluoromethylated polycyclic γ ‐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 γ ‐sultone and mercaptoalkanol. Sodium fluoroalkanesulfinates were utilized as bifunctionalization reagents for both fluoromethyl groups and SO 2 . The cyclization proceeds through a stepwise photoinduced radical addition followed by an intramolecular 5‐ exo‐tet anionic substitution cyclization after SO 2 insertion.