Iodine Promoted Efficient Synthesis of 2-Arylimidazo[1,2-a]pyridines in Aqueous Media: A Comparative Study between Micellar Catalysis and an On-Water Platform

In a new and environmentally sustainable approach, a series of 2-arylimidazo[1,2-a]pyridine derivatives were synthesized in aqueous media in the presence of iodine as a catalyst. The reaction proceeded by condensation of various aryl methyl ketones with 2-aminopyridines to afford 2-arylimidazo[1,2-a]pyridines in good overall yields. Although several of the reactions were efficiently performed on water, the addition of a surfactant, namely, sodium dodecyl sulphate, was found effective in terms of substrate scope and yield enhancement. Both methods were successfully used for the gram-scale synthesis of a marketed drug, zolimidine. The simple experimental setup, water as green media, and inexpensive catalyst are some of the merits of this protocol.