A simple and efficient one-pot synthesis of novel benzimidazo[1,2-a]- chromeno[4,3-d] pyrimidinones catalyzed by [Et3NH][HSO4]

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 [Et3NH][HSO4] 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