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

N-和S-叶立德重排反应机理的比较：量子理论研究

基本信息

批准号：
10671992
负责人：
SHIRAI Naohiro
金额：
$ 0.7万
依托单位：
Nagoya City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671992/
关键词：
ylide sigmatropic rearrangement allyl rearrangement benzyl rearrangement early transition state ab initio (p-d) pai ineraction interaction of lone pair electron with pai electron (p-d)π相互作用 allyl転位 benzyl転位 MOPAC ab intio B3LYP /

项目摘要

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.

当反应物在N-叶立德或S-叶立德的[2,3]σ向重排反应中分子中具有两个不同的活性点（烯丙基和苄基）时，实验结果表明N-叶立德的选择性较差，S内立德仅产生一种产物，通过分子轨道理论研究了化学选择性的差异。内立德的几何形状和[2,3] sigmatropic 的过渡态。通过不同的计算水平对重排进行了优化，并估计了反应的能垒。使用密度泛函方法从头计算的半经验计算未能分析差异的原因（B3L YP/6-31G水平显示了过渡态）。 N-叶立德重排是早期过渡结构，S-叶立德重排是晚期过渡结构。这些过渡结构受孤叶立德反应性的影响很大。 S原子上的孤对电子稳定了S-叶立德，得到了后期跃迁结构。本研究结果验证了Evans-Polanyi提案。在本研究过程中，发现S原子上的孤对电子与π相互作用。苯环体系对锍盐构象的影响通过B3LYP/6-31GiD1*IeD1进行定量分析。