Ultrasonic-mediated catalyst-free rapid protocol for the multicomponent synthesis of dihydroquinoline derivatives in aqueous media

Abstract

Catalyst-free multicomponent protocol for the condensation of malononitrile, 2-naphthol/resorcinol, aldehydes, and ammonium acetate in aqueous medium under ultrasound irradiation at 60oC afforded a wide range of valuable dihydroquinolines in high yields (90–97%) with short reaction times (60–90 min). This approach offers vital improvements for the synthesis of target compounds with regard to yield of products, simplicity in operation, utilization of water as solvent, and green aspects by avoiding the catalysts or solvents.