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B-甲基硼杂噁唑烷在羰基化合物的不对称还原反应中有很高的立体选择性,对B-甲基硼杂噁唑烷在不对称合成反应中的催化机理的研究将对以后不对称合成反应催化剂的选择有较强的理论指导作用。本文利用量子化学的半经验方法,通过对B-甲基硼杂噁唑烷在反应中形成的各种可能的中间过渡态的能量和前线轨道能的计算,进一步对反应的机理进行了分析,发现原来被认为是优势的椅式六元环过渡中间态构像并不象想象中那样稳定,计算结果表明船式的中间过渡态A24形成较为对称的LUMO轨道,活化能较低,所得产物与实际情况相符,被确定为反应中间过渡态的构像,得出了定性的结论,在理论上为以后的不对称合成催化剂的设计和应用提供了一定的指导。
B-Methylboroxazolidine has a high stereoselectivity in the asymmetric reduction of carbonyl compounds. The study on the catalytic mechanism of B-methylboroxazolidine in the asymmetric synthesis of Asymmetric synthesis reaction catalyst has a strong theoretical guidance. In this paper, the semi-empirical methods of quantum chemistry were used to further analyze the reaction mechanism by calculating the energies and frontier orbital energies of various possible intermediate transition states formed by B-methylboroxazolidine. It was found that the six-membered ring-like intermediate transitional structure was not considered as stable as expected. The results show that the ship intermediate transition state A24 forms a symmetric LUMO orbit and the activation energy is low. The results are in good agreement with the actual situation and are confirmed as the conformation of the reaction intermediate transition state. The conclusion is given qualitatively and provide some guidance for the design and application of the later asymmetric synthesis catalyst in theory.