Room Temperature Benzofused Lactam Synthesis Enabled by Cobalt(III)‐Catalyzed C(sp2)−H Amidation

Benzofused lactams, especially indolin‐2‐one and dihydroquinolin‐2‐one are popular structural motives in durgs and natural products. Herein, we developed a room temperature and robust synthesis of benzofused lactams through cobalt(III)‐catalyzed C(sp2)−H amidation. In this protocol, in‐situ formation of Cp*Co(III)(ligand) catalyst from Cp*Co(CO)I2 and ligand simplify the synthetic effort of cobalt complexes. Simple and readily synthesized 1,4,2‐dioxazol‐5‐ones underwent room temperature intramolecular C−H amidation and afforded a wide variety of functionalized benzofused lactams in up to 86% yield. The scalability of the reaction is also be demonstrated.