Ruthenium(III) chloride efficiently catalyzes the three-component Biginelli reaction of an aldehyde, a β-keto ester, and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidine-2-(1H)-ones in excellent yields.
pyrimidinones - ruthenium - aldehyde - Biginelli reaction - solvent-free conditions - heterocycles