双官能团离子液体[Promim]^＋[CF3CO2]^-支撑不对称Aldol反应的密度泛函理论研究

用密度泛函理论B3LYP方法对双官能团离子液体[Promim]+[CF3CO2]-支撑丙酮与邻-硝基苯甲醛不对称aldol反应进行了研究.结果表明,该离子液体的脯胺酸和咪唑基团一起对反应产生催化作用.整个反应包括:丙酮的羰基与脯胺酸基团的胺基间的亲核加成反应,咪唑2-位氢参与的脱水反应生成亚胺IM1-2,丙酮甲基脱氢反应生成烯胺I M1-3,苯甲醛与烯胺的亲核加成反应,水加成反应和催化剂再生反应.第一步骤是速率控制步骤,产物羟基位碳原子的手性在苯甲醛与烯胺的亲核加成反应中产生.另外,在咪唑环2-位氢参与的脱水反应中生成的水分子辅助丙酮甲基脱去α-氢生成烯胺.苯甲醛邻位吸电子基团能降低醛基碳原子的电子密度,增强醛基碳原子的亲电性,从而增强反应物活性.离子液体[Promi m]+[CF3CO2]-产生的溶剂化效应使反应势垒降低(除开催化剂再生步骤).

DFT Study on the Bifunctional Ionic Liquid [Promim]~+ [CF_3CO_2]~--Supported Asymmetric Aldol Reaction

By using the B3LYP method of the density functional theory(DFT),the bifunctional ionic liquid(IL) [Promim]+ [CF3CO2]--supported asymmetric aldol reaction between ketone and o-nitrobenzaldehyde is theoretically studied.The results demonstrate that bifunctional proline and imidazole fragments of the IL coordinate to catalyze the reactions.The overall reactions are initiated by a nucleophilic addition reaction of the proline fragment with the carbonyl group of ketone,and subsequently go through a dehydration r...