Design and synthesis of 2-phenylimidazo[1,2-a]pyridines as a novel class of melatonin receptor ligands.

Abstract A novel class of imidazo[1,2- a ]pyridines as melatonin receptor ligands is designed and synthesized. The affinities of 3-(6-methoxy-2-phenylimidazo[1,2- a ]pyridine-3-yl)- N -methyl-propionamide 8 , N -[2-(6-methoxy-2-phenylimidazo[1,2- a ]pyridine-3-yl)-ethyl]-acetamide 13 and N -(1-hydroxy-3-(5-methoxy-2-phenyl-1H-indol-3-yl)propan-2-yl)acetamide 18 are evaluated for binding on melatonin receptors. Compound 8 present good selectivity for MT 2 over MT 1 (MT 1 /MT 2  = 19) and compound 13 have good affinities for both MT 1 (Ki :28 nM) and MT 2 (Ki : 8 nM).