PPh3催化Mannich反应机理的密度泛函研究  

A DFT mechanistic study on the PPh3-catalyzed Mannich reaction

作　　者：王万辉 杨亚静 李阳 包明[1,2] WANG Wan-hui;YANG Ya-jing;LI Yang;BAO Ming(State Key Laboratory of Fine Chemicels,Dalian University of Technology,Dalian 116023,China;School of Petroleum and Chemical Engineering,Dalian University of Technology,Panjin 124221,China)

机构地区：[1]大连理工大学精细化工国家重点实验室,辽宁大连116023 [2]大连理工大学石油与化学工程学院,辽宁盘锦124221

出　　处：《分子科学学报》2020年第2期153-159,I0005,共8页Journal of Molecular Science

基　　金：辽宁省自然科学基金资助项目(20170540170);中央高校基本科研业务费专项资金资助项目(DUT18LK14)。

摘　　要：通过密度泛函理论研究了PPh3催化苯胺、苯甲醛和乙酰乙酸乙酯三组分Mannich反应的机理.计算结果表明该机理主要分3个步骤进行:PPh3催化乙酰乙酸乙酯发生酮式-烯醇式互变异构得到烯醇;烯醇辅助苯胺和苯甲醛缩合并脱水生成亚胺;亚胺和烯醇通过加成反应生成β-氨基羰基化合物.通过详细的机理研究,发现烯醇从亚胺的背面进攻其亲电C原子的过渡态的相对能量更低,容易得到反式的产物,对实验观察到的非对映选择性进行了合理的解释.Density functional theory calculations were carried out to study the mechanisms of PPh3-catalyzed three-component Mannich reaction of aniline,benzaldehyde,and ethyl acetoacetate.Our calculation results supported that the reaction proceeds in three distinct steps:PPh3-catalyzed keto-enol tautomerism of ethyl acetoacetate to give enol,enol-assisted condensation of aniline and benzaldehyde followed by dehydration to give imine,and the nucleophilic enol attack on the electrophilic carbon of imine to finally give theβ-amino carbonyl products.The detailed mechanistic study also sugguested that the transition state of the enol re-face attack on the electrophilic carbon of imine showed a lower energy barrier and consequently anti-product was formed preferably.This calculation rationalized the observed diastereoselectivity in experiments.

关 键 词：DFT研究 反应机理 MANNICH反应 非对映选择性 

分 类 号：O641[理学—物理化学]