Comparison of the Reaction Mechanism of N- and S- ylide rearrangement : A Quantum Theoretical Study

当分子在[2，3] N-或S-酰亚胺的不同基质重新排列时，反应剂有两个不同的活性点（烯基组和苯基组）时，实验结果显示N-酰亚胺的选择性较差，S-酰亚胺只给了一种产品。根据分子轨道理论的研究，化学电子学的差异;[2，3]百合花的几何学和[2，3]的过渡状态的sigmatropic rearrangement被各种计算水平和能量障碍的优化优化。半经验计算失败了，无法分析不同的原因。Ab initio calculations with Density Functional Method （B3L YP/6- 31 G-D1*-D1 level show that the transition states of the N-ylide rearrangement are early transition structures and those of the S-ylide are？transition structures）。这些过渡结构对伊斯兰教的反应有很大的影响。S原子的单对电子稳定器，使S-ylide能够提供后期过渡结构。本研究证实了Evans-Polanyi提案的结果。在本研究程序的过程中，发现了与硫基盐环影响构成的单对电子原子相互作用的π系统。根据B3 LYP/6- 31 G型D1* 型D1.

When a reactant has two different active points (allyl group and benzyl group) in the molecule in [2,3] sigmatropic rearrangement of N- or S- ylides, the experimental results showed that selectivity of the N-ylide was poor and the S-ylide gave only one product. Difference of the chemoselectivity was investigated by molecular orbital theory.Geometries of the ylides and the transition state of the [2,3] sigmatropic rearrangement were optimized by various calculation levels and energy barriers for the reaction were estimated. Semi-empirical calculations failed to analyze the reason of the difference. Ab initio calculations with Density Functional Method (B3L YP/6-31GィイD1*ィエD1 level show that the transition states of the N-ylide rearrangement are early transition structures and those of the S-ylide are late transition structures. These transition structures are much affected by reactivity of the ylides. Lone pair electron of S atom stabilize the S-ylide to give the late transition structure. Result of this study verified the Evans-Polanyi Proposal.In the process of this research program, it was found that interaction of lone pair electron on S atom with π system of phenyl ring influence conformation of the sulfonium salt. The influence was quantitatively analyzed by B3LYP/6-31GィイD1*ィエD1.