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手性催化剂奎尼丁催化丙二酸乙酯与苯并噻唑亚胺的不对称Mannich反应机理研究,对β-氨基酸酯类衍生物合成具有重要的指导意义.采用密度泛函理论(DFT)的M06-2X方法,通过精确计算:(1)确定了奎尼丁催化剂催化活性位点为9位碳上的羟基和位于1位的叔氮原子;(2)S构型反应过渡态能量比R构型反应过渡态能量低,反应产物以S构型为主;(3)计算进一步表明较低温度有助于提高反应的立体选择性.计算结果与实验数据相符,反应获得S构型的β-氨基酸酯类衍生物,其ee可达到81%-95%.
The asymmetric Mannich reaction mechanism of quinidine catalyzed by ethylbenzene and benzothiazoleimine is of great importance to the synthesis of β-amino acid ester derivatives.Using density functional theory (DFT) M06-2X method, by means of accurate calculation: (1) It is confirmed that the catalytic site of quinidine catalyst is the hydroxyl group on the 9 carbon atom and the tertiary nitrogen atom located at the 1 position; (2) the transition state energy ratio R The energy of the transition state is low, and the reaction product is mainly in the S configuration. (3) Calculations further indicate that the lower temperature is helpful to improve the stereoselectivity of the reaction. The calculated results are in good agreement with the experimental data, - Amino acid ester derivatives, the ee up to 81% -95%.