Regioselective synthesis of imidazo[1,5-: A] quinoxalines and methyl N -phenylbenzimidats on an ionic liquid support

An ionic liquid (IL) supported, regioselective synthesis of imidazo[1,5-a]quinoxalines and methyl N-phenylbenzimidats under microwave conditions was reported. The IL-immobilized aromatic amines were reacted with various ketones and aliphatic aldehydes using an unconventional Pictet-Spengler reaction to generate polycyclic imidazo[1,5-a]quinoxalines. Alternatively, aromatic aldehydes afforded auto-oxidized imidazo[1,5-a]quinoxalines first which further converted to novel methyl N-phenylbenzimidats unexpectedly during the cleavage of the IL-support. In the reported strategy, rapidness is achieved through microwave conditions while the IL-support assists purification by simple precipitation.