Nickel/iodine-catalyzed synthesis of 2-arylimidazo[1,2-a]pyridines through Ortoleva-King type protocol

Abstract

A novel Ni-I2 catalytic system was introduced for the synthesis of 2-arylimidazo[1,2-a]pyridines from readily available arylmethyl ketones and 2-aminopyridines as the starting materials. The method uses efficient and cost-effective NiCl2·6H2O catalyst and molecular iodine to provide a range of 2-arylimidazo[1,2-a]pyridines in moderate to good yields through the Ortoleva-King type protocol. The transformation is proposed to follow a sequence of α-iodination/Ortoleva-King type reaction/cyclization. The method was effectively utilized in the synthesis of Zolimidine, a gastroprotective drug.