1983年W.C.Still 和 C. Gennari第一次应用HWE反应的改进法通过醛制备(Z)-构型烯烃。膦酸二(三氟乙基)酯和醛在强碱条件下制备(Z)-α,β-不饱和酮或酯的反应。
反应机理
强碱拔氢,得到膦酸酯碳负离子,然后对醛进行加成得到的螯合物迅速重排生成氧磷杂环氧丁烷中间体,消除得到烯烃。消除得到速度比开始加成的速度快,导致整个反应过程不可逆(而常规的HWE反应过程可逆,是热力学控制),而此反应是动力学控制。
赤式异构体是动力学控制产物。
反应实例
参考文献
1. Still, W. C.; Gennari, C. Tetrahedron Lett. 1983, 24, 4405-4408. W. Clark Still
(1946) was born in Augusta, Georgia. He was a professor at Columbia University.
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10. Rong, F. Horner–Wadsworth–Emmons reaction. In Name Reactions for Homologations-Part I; Li, J. J., Ed.; Wiley: Hoboken, NJ, 2009, pp 420-466. (Review).
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编译自:Name Reactions (A Collection of Detailed Reaction Mechanisms), Jie Jack Li, Still–Gennari phosphonate reaction,page 582-583.