Palladium-Catalyzed Electro-oxidative C-H Amination toward the Synthesis of Pyrido[1,2- a]benzimidazoles with Hydrogen Evolution

Transition-metal-catalyzed oxidative C-H/N-H coupling reaction is an important method to construct C-N bonds. However, stoichiometric oxidants were usually necessary. Here, we report a palladium-catalyzed electro-oxidative intramolecular C-H/N-H annulation reaction without an external oxidant or additive. A variety of pyrido[1,2-a]benzimidazoles were constructed by a simple, green, and mild path. Experimental results suggested that Pd(0) could be oxidized on the anode to be recycled.