Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Using Ce(SO4)2-SiO2 as a Heterogeneous and Recyclable Catalyst

A simple and efficient synthesis of 3,4-dihydropyrimidinones or thiones is described, using silica-supported ceric sulfate [Ce(SO4)2-SiO2] as a heterogeneous catalyst from an aldehyde, 1,3-dicarbonyl compound, and urea or thiourea at 110 degrees C under solvent-free conditions. Compared with the classical Biginelli reaction, this new method consistently has better yields, short reaction time, easy separation, and tolerance toward various functional groups.