I sub(2)-DMSO-PTSA: a simple and metal free oxidative cross coupling of imidazo[1,2-a]pyridines and methylketones

A simple, highly efficient and selective oxidative cross coupling of imidazo[1,2-a]pyridine (IP) compounds (1) and methylketones (2), promoted by molecular iodine in DMSO in the presence of a catalytic amount of PTSA has been realized in a one pot reaction. This strategy has provided a general route for the synthesis of 1-aryl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethan e-1,2-diones (3) with a new C-C bond formation through Kornblum oxidation followed by nucleophilic attack of IP compounds (1) on the in situ formed phenylglyoxal. Simple reaction conditions, no metal catalysts and selective product formation are the advantages of this protocol.