Novel one step synthesis of imidazo[1,2-a]pyridines and Zolimidine via iron/iodine-catalyzed Ortoleva-King type protocol

Imidazo1,2-a]pyridines form versatile scaffolds in pharmaceutical industry arising from their diverse biological activities. The synthesis of these molecules thus has been of great interest and resulted in the development of a large number of new methodologies. Herein we describe the first iron-catalyzed Ortoleva-King type protocol towards the synthesis of these fused heterocyclic compounds. This methodology employs cheap and easily available FeCl₃·6H₂O and molecular iodine as the catalytic system. The procedure has been well explored by extending the substrate scope with a variety of aromatic ketones and 2-aminopyridines to furnish different imidazo1,2-a]pyridine derivatives in moderate to good yields. A successful application of this protocol was also demonstrated by achieving direct one step synthesis of the gastro protective drug, Zolimidine.