Fusion of β-enaminones and 2-aminopyridines to 3-oyl-imidazo[1,2-a]pyridines induced by iodine: a mechanochemical approach

Abstract

Metal and additive-free, one-step synthesis of 3-oyl-imidazo[1,2-a]pyridines was accomplished by the solid-state manual grinding of β enaminones, 2-aminopyridines and molecular iodine. The reaction proceeds by the addition of 2-aminopyridine to β-enaminone in a Michael fashion, and the in situ formed adduct undergoes intramolecular endo-cyclization induced by molecular iodine leading to the title product. Simple reaction conditions, short reaction time, no column purification and excellent yields are the advantages of the protocol. Furthermore, this methodology also offers superior yields for previously reported compounds, and this is the first report on the synthesis of the title compounds from β-enaminones, through grindstone chemistry.