An efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones via a three-component Biginelli
condensation of aldehyde, ethyl acetoacetate, and urea or thiourea in the presence of a catalytic amount of ascorbic acid (5
mol %) is described. The reaction proceeded efficiently under solvent-free conditions at 80 °C to afford the desired products
in moderate to good yields.