One-Pot Synthesis of Indoles from Alkynes and Anilines through Palladium-Catalyzed Double C-H Activation using O2as the oxidant

A simple and efficient Pd-catalyzed tandem procedure for the synthesis of β-cyanoindoles was achieved. Unactivated anilines and cyanoalkynes were employed as the starting materials to go through nucleophilic additions to form the N-aryl enamine intermediate, and then followed by Pd-catalyzed double C−H activation to yield the product in one pot. Moderate to good yields were achieved for 19 examples. LiBr was used as the additive to promote the process. Oxygen was used as the sole oxidant, thus high atom efficiency could be achieved.