Efficient Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones over Silica Sulfuric Acid as a Reusable Catalyst under Solvent-free Conditions

Abstract

3,4-Dihydropyrimidin-2(1H)-ones and their sulfur analogues are efficiently synthesized by the three-component condensation of β-dicarbonyl compounds, aromatic and aliphatic aldehydes, and urea or thiourea in the presence of catalytic amounts of silica sulfuric acid under solvent-free conditions in high yields.The catalyst is recyclable and can be used several times without any decrease in the products yields.The Biginelli reaction was first reported more than a century ago and recently has been reviewed. 1,2hydropyrimidinones (DHPMs), the products of Biginelli reaction, and their derivatives have attracted