Sulfonyl Radical-Induced Regioselective Cyclization of Enamide-Olefin To Form Sulfonylated 6-7-Membered Cyclic Enamines.

Remarkable progress has been made in the radical cascade cyclization of heteroaryl- or aryl-tethered alkenes to construct benzene-fused frameworks via the cracking of aryl C-H bonds. In contrast, the radical cascade cyclization of linear dienes through the cracking of vinyl C-H bonds to construct nonbenzene-fused ring frameworks with endocyclic double bonds has significantly lagged behind, and major advances have largely been restricted to the generation of 5-membered heterocycles, such as pyrrolinones. Herein, we report the silver-mediated regioselective sulfonylation-cyclization of linear dienes with sodium sulfinates to form sulfonylated 6- and 7-membered cyclic enamines.