One-pot formal [3 + 2] annulation of 2-pyridinyl-substituted p -quinone methides and arynes for the synthesis of 3-aryl pyrido[1,2- a ]indoles.

An efficient and metal-free method for the synthesis of 3-aryl pyrido[1,2- a ]indoles from aryne intermediates and 2-pyridinyl-substituted p -QMs was successfully developed under ambient conditions. The reaction offered a novel and practical protocol to access some diverse functional molecules in good to excellent yields. The proposed mechanism indicated that the reaction proceeded via a formal [3 + 2] cycloaddition step.