Water-tolerant and reusable Lewis acid catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions.

3,4-Dihydropyrimidin-2-(1H)-ones were synthesized in high yields by a one-pot cyclocondensation of an aldehyde, a 1,3-dicarbonyl compound, and urea using copper methanesulfonate (2 mol%) as a recyclable catalyst under solvent-free conditions in short reaction time (1-2 h).