Synthesis of imidazo[1,2-a]pyridines a ]pyridines via cobalt/iodine-catalyzed Ortoleva-King type approach

Ortoleva-King type reaction of 2-aminopyridines with easily available aromatic ketones by dual catalytic system of cobalt and iodine in chlorobenzene was proposed. The reaction made use of the in situ formation of alpha-halo ketones from aromatic ketones and molecular iodine. An array of functional groups were tolerated in this strategy to allow the synthesis of variously substituted imidazo[1,2-a]pyridines a ]pyridines in moderate to good yields. Furthermore, this procedure was effectively used for the synthesis of zolimidine, a medicine that is sold as an anti-ulcer agent.