Copper-Catalyzed Dehydrogenative C(sp2)–N Bond Formation via Direct Oxidative Activation of an Anilidic N–H Bond: Synthesis of Benzoimidazo[1,2-a]indoles

A dehydrogenative C(sp2)–N bond-forming strategy via copper-catalyzed intramolecular C–H/N–H coupling has been developed, which systematically unraveled the feasibility and practicality for benzoimdazo[1,2-a]indole formations through oxidative anilidic N–H activation. The merit of this strategy is illustrated by the broad tolerance of functionalities, as well as the utilization of extremely cheap copper catalysis to realize potentially useful indole-fused tetracycles in a step- and atom-economical manner.