9-氨基奎宁催化剂催化1-溴代硝基甲烷和亚苄基丙酮的共轭加成反应的理论研究

Theoretical Studies on the Conjugate Addition of 1-Bromonitromethane to Benzylidene Acetone Catalyzed by 9-Amino-9-deoxyepiquinine

通过密度泛函理论(DFT)B3LYP,M062X和从头算方法 MP2,给出了9-氨基奎宁作为有机催化剂和苯甲酸作为辅助催化剂催化1-溴代硝基甲烷与亚苄基丙酮的不对称共轭加成反应的详细反应机理.反应过程主要包括3个阶段:(1)亚胺离子中间体的形成;(2)亚胺离子与1-溴代硝基甲烷的亲核加成;(3)水解并伴随催化剂的还原.计算结果不仅解释了苯甲酸加合物在亚胺离子形成过程中所起的重要作用,而且提供了一般反应模型以理解这个共轭加成反应的反应机理和对映选择性.

Asymmetric conjugate addition of 1-bromonitromethane tobenzylidene acetone was catalyzed by 9-amino-9-deoxyepiquinine as organic catalyst and benzoic acid as co-catalyst. We had identified a detailed mechanism of the title reaction with density functional theory（ B3LYP and M062X） and ab initio calculations （MP2）. The reaction process includes three major stages： （ 1 ） the formation of an iminium ion intermediate; （2） the nucleophilic addition between the iminium and 1-bromonitromethane ; （3） hydrolysis and recovery of catalyst. The calculated results not only explain benzoic acid as acidic additive plays an important role in the formation of the key reaction iminium intermediate, but also provide a general model to help explain the mechanism and enantioselectivity of the conjugate addition reaction.