One pot synthesis of 3,4-dihydropyrimidin-2(lH)-ones/-thiones catalysed by zinc chloride:An improved procedure for the Biginelli reaction using microwaves under solvent free condition

摘要

Zinc chloride efficiently catalyzes the three-component coupling of p-keto ester,substituted aldehyde and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(lH)-ones/thiones respectively,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 20-35 sec.