硼氢化钠还原潜手性酮反应机理的量子化学研究韩卫华.pdf

2006 年第 64 卷 化 学 学 报 Vol. 64, 2006 第 16 期, 1723～1729 ACTA CHIMICA SINICA No. 16, 1723～1729 ·研究论文· 硼氢化钠还原潜手性酮反应机理的量子化学研究 韩卫华a 李浩然*,a 邓东顺b 王 勇a a ( 浙江大学化学系 杭州 310027) b ( 浙江工业大学药学院 杭州 310014) 摘要 用从头计算方法对硼氢化钠不对称还原对甲基环己酮的机理进行了研究. 探讨了四元环和六元环机理, 其中每 种机理有三种途径, 主要的途径是经过过渡态的两步反应途径. 计算结果表明, 无溶剂参与反应的四元环过渡态机理 虽然能解释其还原历程, 但计算所得的对映体组成与文献值相差很大. 而对质子性溶剂异丙醇参与的六元环机理的研 究发现反应产物的对映体组成的计算结果与文献实验值吻合较好. 这表明该反应主要经历六元环过渡态的两步反应历 程. 关键词 对甲基环己酮; 硼氢化钠; 还原机理; 过渡态 Quantum Chemistry Study on the Reduction of Prechiral Ketone by Sodium Borohydride HAN, Wei-Huaa LI, Hao-Ran*,a DENG, Dong-Shunb WANG, Yonga a ( Department of Chemistry, Zhejiang University, Hangzhou 310027) (b College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014) Abstract The asymmetric reduction mechanism of p -methylcyclohexanone by sodium borohydride was investigated with ab initio calculations. Four-member ring and six-member ring mechanisms have been studied, both of which have three reaction paths with the main path through two-step transition state. The study shows that though four-member ring transition state mechanism without solvent participation could explain the reduction of p -methylcyclohexanone reasonably, the ca