In-Plane Vinylic SN2 Substitution and Intramolecular β Elimination of β-Alkylvinyl(chloro)-λ3-iodanes
In-Plane Vinylic SN2 Substitution and Intramolecular β Elimination of β-Alkylvinyl(chloro)-λ3-iodanes
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β-烷基乙烯基（氯）-λ3-碘的面内乙烯基 SN2 取代和分子内 β 消除
DOI：
10.1021/ja972267c
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发表时间：
1998
影响因子：
15
通讯作者：
M. Ochiai
中科院分区：
文献类型：
--
作者：
T. Okuyama;T. Takino;Koichiro Sato;M. Ochiai
研究了四种(E)-β-烷基乙烯基（苯）碘盐在乙腈和其他几种溶剂中与氯离子的反应。β-甲基、β-辛基和β-异丙基取代的碘盐经过竞争性的双分子亲核取代形成相应的(Z)-1-氯-1-烯烃，在乙烯基碳上发生构型反转，并消除形成1-炔。β-叔丁基取代碘盐只提供消除反应的产物。反应物的紫外吸收光谱显示氯离子和碘离子快速转化为相应的氯-λ - 3-碘的平衡混合物，其缔合常数为5600 ~ 7600 mol-1 dm3。动力学分析表明，大部分取代产物和消除产物都是由λ3-碘烷反应产生的。有证据表明，取代反应是通过协调的双分子SN2机制进行的，消除反应是通过单分子反应进行的。
The reactions of four (E)-β-alkylvinyl(phenyl)iodonium salts with chloride ion were examined in acetonitrile and in several other solvents at 25 °C. The β-methyl-, β-octyl-, and β-isopropyl-substituted iodonium salts undergo competitive bimolecular nucleophilic substitution to form the corresponding (Z)-1-chloro-1-alkene with inversion of configuration at the vinylic carbon and elimination to form the 1-alkyne. The β-tert-butyl-substituted iodonium salt affords only the products of the elimination reaction. The UV absorption spectra of the reactants show the rapid coversion of chloride and iodonium ions to an equilibrium mixture of the corresponding chloro-λ3-iodane, with an association constant of 5600−7600 mol-1 dm3. A kinetic analysis shows that most of the substitution and elimination products form from reaction of the λ3-iodane. Evidence is presented that the substitution reaction proceeds by a concerted bimolecular SN2 mechanism and that the elimination reaction proceeds by a unimolecular reaction m...