One pot synthesis of 3,​4-​dihydropyrimidin-​2(1H)​-​ones​/-​thiones catalyzed by zinc chloride: An improved procedure for the Biginelli reaction using microwaves under solvent free conditions

摘要

Zn chloride efficiently catalyzes the three-​component coupling of β-​keto ester, substituted aldehyde and urea or thiourea to afford the corresponding 3,​4-​dihydropyrimidin-​2(1H)​-​ones​/thiones, resp., the new protocol for the Biginelli reaction under microwave irradn. works in the absence of solvent, the yields are high and the reaction goes to completion within 20-​35s.