表面活性剂和质子酸协同催化合成3,4-二氢嘧啶-2-酮

经典的Biginelli反应用盐酸作催化剂,通常收率较低(20%~50%),而表面活性剂和质子酸协同催化能有效的促进Biginelli反应进行。以苯甲醛、β-酮酸酯和尿素三组分为反应物,再加入表面活性剂(β-环糊精)和盐酸,用乙醇作溶剂,缩合制备3,4-二氢嘧啶-2-酮。考察了反应物摩尔比、反应时间、β-环糊精的物质的量和不同表面活性剂等因素对收率的影响。结果表明,在苯甲醛、β-酮酸酯、尿素的摩尔比为1.0∶1.2∶1.5,β-环糊精的物质的量为2.5 mmol,浓盐酸的体积为0.25 mL,乙醇的体积为25 mL,回流时间为8 h的条件下,3,4-二氢嘧啶-2-酮收率达到92%。

Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones Using Protic Acid Surfactant and Synergistic Catalysis

The yield of the classical Biginelli reaction is low(20%～50%) when hydrochloric acid is used as catalyst,but synergistic catalysis of surfactant combined with proton acid could accelerate the Biginelli reaction effectively.3,4-Dihydropyrimidin-2(1H)-ones was synthesized under the condition of β-cyclodextrin as surfactant combined with hydrochloric acid in ethanol solution,and the condensation substrates were benzaldehyde,β-ketoacid ester and urea.The effects of substrate mole ratio,reaction time,the amount of β-cyclodextrin and other surfactants on the yields were investigated.The results show that the yield of 3,4-dihydropyrimidin-2(1H)-ones is up to 92%,under the conditions of 1.0∶1.2∶1.5 mole ratio of benzaldehyde,β-ketoacid ester and urea,2.5 mmol β-cyclodextrin,0.25 mL hydrochloric acid,25 mL ethanol,and 8 hours refluxing time.