Regioselective Synthesis of Indole-Fused Seven-Membered N-Heterocycles via Photoredox-Catalyzed Intramolecular Cyclization

Herein, we describe the construction of indole-fused seven-membered N-and O-heterocycles from indolyl alpha-diazo-carbonyls via photoredox-catalyzed intramolecular cyclization. The photoredox process features operational simplicity, mild conditions, and as low as 0.1 mol % catalyst loading. The tricyclic heterocycles are obtained in yields of 24 to 67% with excellent regioselectivity. The practicality of this protocol is further demonstrated by gram-scale reactions carried out in both batch and continuous flow.