Synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones under microwave irradiation

SnCl2.2H2O efficiently catalyzes the three component coupling of β-keto ester, substituted arylaldehyde and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones/thiones, the new protocol for the Biginelli reaction under microwave irradiation works in the absence of solvent, the yields are high and the reaction goes to completion within 20-40 secs