Clean and one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thione derivatives using maleic acid as an efficient and environmentally benign natural di-functional Bronsted acid catalyst under solvent-free conditions

An efficient synthesis of Biginelli-type compounds using maleic acid as an economical di-functional Bronsted acid catalyst in a one-pot, three-component reaction of beta-ketoesters (methyl or ethyl acetoacetate), aromatic aldehyde (benzaldehye derivatives) and urea or thiourea is reported. The present methodology is an environmental friendly approach to access 3,4-dihydropyrimiclin-2-(1H)-ones/tiones derivatives. It offers several merits such as good yields, short reaction times, efficient, eco-friendly, solvent-free conditions, materials available, and simple operational procedure with no column chromatographic separation. The products have been characterized by melting points and H-1 NMR spectroscopy.