Catalytic Asymmetric Synthesis and Reactions of Enolates

烯醇化物在合成有机化学中起着核心作用。研究了通过手性螯合的氨基锂或其相应的胺使烯醇化锂的合成和反应具有对映选择性的可能性。基于对这些反应的分析，还尝试将它们转化为所用手性碱的催化剂。催化不对称去质子化：三齿氨基锂对羰基化合物的去质子化速率比二齿氨基锂慢。基于这一新发现，首次实现了手性双齿胺和非手性三齿酰胺锂的组合催化羰基化合物的不对称去质子化反应.催化不对称烷基化：烯醇化锂在四齿胺存在下的烷基化速率比在二齿胺存在下的烷基化速率合理地更快。基于这一新发现，首次实现了手性四齿胺和非手性双齿胺的组合催化烯醇化锂的不对称烷基化反应.催化不对称质子化：在甲苯中存在少于化学计量量的手性四齿胺的情况下，通过不溶性非手性质子源如琥珀酰亚胺实现前手性烯醇化锂的催化不对称质子化。机械细节仍在调查中。

Enolates play a central role insynthetic organic chemistry. Studies have been carried out on the possibility of making the synthesis and reactions of lithium enolates enantioselective through the agency of chiral chelated lithium amides or their corresponding amines. Based on the analysis of these reactions, attempts have also been made to convert them catalytic as to the chiral bases used.1. Catalytic Asymmetric Deprotonation :The rate of deprotonation of carbonyl compounds by a tridentate lithium amide is reasonably slower than that by a bidentate lithium amide. Based on this new finding, catalytic asymmetric deprotonation of carbonyl compounds was realized for the first time by using a combination of a chiral bidentate amine and an achiral tridentate lithium amide.2. Catalytic Asymmetric Alkylation :The rate of alkylation of lithium enolate in the presence of a tetradentate amine is reasonably faster that that in the presence of a bidentate amine. Basedon this new finding, catalytic asymmetric alkylation of lithium enolates was realized for the first time by using a combination of a chiral tetradentate amine and an achiral bidentate amine.3. Catalytic Asymmetric Protonation :Catalytic asymmetric protonation of prochiral lithium enolates was realized in the presence of less than a stoichiometric amount of a chiral tetradentate amine in toluene by insoluble achiral proton sources such as succinimide. Mechanistic details are still under investigation.