Visible-Light Photoredox-Catalyzed Synthesis of Phosphorylated γ-Sultines via Radical-Polar Crossover Cyclization.

A three-component cascade radical addition/SO2 incorporation/5-exo-tet cyclization of alkenes with secondary phosphine oxides and DABCO·(SO2)2 has been developed via visible-light-induced photoredox catalysis. Under mild and operationally simple conditions, a diverse range of phosphorylated γ-sultines were afforded in moderate to good yields. Furthermore, this reaction features high diastereoselectivity, a broad substrate scope, and good functional group tolerance. Further transformations of phosphorylated γ-sultine products demonstrate the potential applications of this approach. Preliminary mechanism studies indicate that this reaction likely proceeds through a radical-polar crossover cyclization.