A simple and efficient one-pot synthesis of novel benzimidazo[1,2- a ]- chromeno[4,3- d ] pyrimidinones catalyzed by [Et 3 NH][HSO 4 ]

A simple and efficient one-pot synthesis of novel polyheterocyclic benzimidazo[1,2- a ]- chromeno[4,3- d ]pyrimidinones 4 via a three-component condensation of 2-aminobenzimidazole 1 , aromatic aldehydes 2 and 4-hydroxy coumarin 3 catalyzed by Bronsted acid ionic liquid triethyl ammonium hydrogen sulphate [Et 3 NH][HSO 4 ] under solvent-free conditions is reported. The main advantages of this protocol are short reaction time, easy work-up, operational simplicity, and excellent yields with high purity, without intervention of chromatography.