Gallium (III) chloride-catalyzed synthesis of 3,4-dihydropyrimidinones for Biginelli reaction under solvent-free conditions

Abstract We describe the syntheses of 3,4-dihydropyrimidinones or analogous thioketones by a one-pot cyclocondensation of acetoacetates, aldehydes and urea or thiourea using gallium (III) chloride as catalyst under solvent-free conditions. The improved Biginelli reaction not only features a simple procedure, high yields and easy purification of production, but also the recycled catalyst could be directly reused for many times while the yields of reaction would not decrease.