标题：Calix[8]arene Sulfonic Acid Catalyzed Three-Component Reaction for Convenient Synthesis of 3,4-Dihydropyrimidin-2(1 H )-ones/thiones under Ultrasonic Irradiation
摘要：In this work, the catalytic activity of calix[8]arene sulfonic acid was successfully investigated for the famous Biginelli reaction. Under ultrasonic irradiation, calix[8]arene sulfonic acid could efficiently catalyzed the three-component reaction of aldehydes with ethyl acetoacetate and urea or thiourea in ethanol to afford the corresponding 3,4-dihydropyrimidin-2(1 H )-ones/thiones in 46–93%. The advantages of this method are the easy isolated procedure, short reaction time and low cost of the catalyst.
