Tangstophosphoric acid (H3PW12O40): An efficient and eco-friendly catalyst for the one-pot synthesis of dihydropyrimidin-2(1H)-ones

Tangstophosphoric acid both in bulk form or supported on silica gel efficiently catalyzed the three-component condensation reaction of aldehyde, 1,3-dicarbonyl compound and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in high yields under solvent-free conditions at 80 °C. This catalyst is efficient not only for open chained β-dicarbonyl compounds, but for the cyclic β-diketones, β-diester or β-diamide derivatives such as dimedone, Meldrum’s acid or barbituric acid derivatives.