硼氢化钠还原潜手性酮反应机理的量子化学研究

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.

Quantum Chemistry Study on the Reduction of Prechiral Ketone by Sodium Borohydride

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 calculated ratio of enantiomers could not match the experimental result. The further study of the six-member ring mechanism with the participation of iso-propanol demonstrates that the calculated ratio of enantiomers agrees with the experimental results es- sentially. All above results show that the reaction experiences the six-member ring transition state with two-step path.