Visible-Light-Induced Acyl Radical Cascade Cyclization of Dienes with Acyl Chlorides to Synthesize Benzo[b]azepin-2-one Derivatives

A visible light-induced radical-cascade acylation/cyclization involving 1,7-dienes and acyl chlorides has been developed. This protocol presents a practical and environmentally benign method for the preparation of diverse acyl benzo[b]azepine derivatives in high yields. The gram-scale synthesis and late-stage modification show the applicability of the reaction. Further radical trapping experiments and luminescence quenching studies elucidate the reaction mechanism.