$$\hbox {I}_{2}$$-medi ated amin ation/cycliz ation of ketones with 2- aminopyridines under high-speed b all milling: solvent- and met al-free synthesis of 2,3-substituted imid azo[1,2- a]pyridines and zolimidine

Under solvent-free high-speed ball milling, an I\(_{2}\)-promoted condensation/cyclization of easily available methyl ketones or 1,3-dicarbonyl compounds with 2-aminopyridines has been developed, which allows the quick assembly of 2,3-substituted imidazo1,2-a]pyridines (IPs) with broad molecular diversity, including the antiulcer drug zolimidine. The advantages of high yields, good functional group compatibility, short reaction time (within 90 min), free use of heating, solvent and metal, employment of cheap starting materials, and simple work-up procedure make this protocol a very efficient alternative to traditional synthesis of IPs.