绿色介质在L-丙氨酸催化不对称Aldol反应中的应用及理论研究

L-Alanine catalysed asymmetric aldol reaction in the green medium and theoretical study

以线性氨基酸L-丙氨酸为催化剂,PEG-400∶H2O(3∶2)为反应体系,室温下直接催化环己酮与不同R基取代的芳香醛进行不对称Aldol反应,产物具有良好的对映选择性(68%ee^96%ee)。该方法操作简单,环境友好,催化剂易回收循环利用,利用过渡态理论结合烯胺机理对环己酮与4-溴苯甲醛反应中的过渡态分子构型(TS、SR-anti、TS-RS-anti)进行了理论研究,并在BL3YP/6-311G(2d,2p)理论水平下经IRC计算证明其构型的合理性。

The L-alanine as the simple linear amino acid was used as the catalysts for the direct asymmetric Aldol reaction between aldehydes and ketones in PEG∶H 2O （3∶2） at room temperature. The result showed that the good enantioselectivity enantiomeric excesses were observed （68% ee -96% ee ）. The method is simple, environmentally friendly and easy to recycle the catalyst. The transition state theory and the enamine mechanism were used to study the transition state molecules （TS-SR-anti; TS-RS-anti） in the reaction of cyclohexanone with 4-bromobenzaldehyde. At the same time, the transition state is proved to be reasonable by IRC calculations under the theoretical level of BL3YP / 6 311G （2d, 2p）.