P2O5/SiO2 as an Efficient, Green and Heterogeneous Catalytic System for the Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2-(1H)-ones (and -Thiones)

A simple, green and efficient solventless procedure for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones (and -thiones) from aldehydes, beta-ketoesters and urea or thiourea in the presence of catalytic amount of silica-supported P2O5 (P2O5/SiO2) at 85 degrees C is described. Using this method, the title compounds were produced in high yields.