Knoevenagel and Wittig-Horner reactions in solid-liquid systems, with magnesium oxide or zinc oxide as catalyst. When Wittig-Horner reaction is competitive with Knoevenagel reaction, the catalyst can be modified to give a highly selective reaction ; the addition of dimethylsulfoxide on MgO or heiamethylphosphoric triamide on ZnO gives more efficient catalysts for the Wittig-Homer reaction. The addition of a small
Alumina-supported potassium fluoride is an effective reagent for Michael addition of nitroalkanes on the electrophilic alkenes. followed by cycloalkylation reaction to give cyclopropanes.
A highly chemo- and stereoselectivesynthesis of diethyl (E)-2-(alkylidene)-2-phosphonoacetonitriles via the Knoevenagel condensation reaction of carbonyl compounds with diethyl cyanomethylphosphonate in the presence of zinc chloride has been achieved. By the presented method, various E-isomers of arylmethylidene phosphonates rather than Horner–Wadsworth–Emmons olefination products were obtained in
在氯化锌存在下,通过羰基化合物与氰基甲基膦酸二乙酯的 Knoevenagel 缩合反应,实现了二乙基 ( E )-2-(亚烷基)-2-膦酰基乙腈的高度化学和立体选择性合成。通过所提出的方法,芳基亚甲基膦酸酯的各种E异构体而不是 Horner-Wadsworth-Emmons 烯化产物以良好至优异的产率获得。它们的E构型由 X 射线衍射和 NMR 分析确定。此外,DFT 计算提供了对反应的化学和立体选择性的见解。
Sequential Double Olefination of 2-(Arylmethylidene)-2-phosphonoacetonitrile with Dimsyl Lithium and Aldehydes: A Domino Route to Densely Substituted 1,3-Butadienes
作者:Raghunath Chowdhury、Sunil K. Ghosh
DOI:10.1002/ejoc.200800385
日期:2008.8
stereoselective synthesis of densely substituted 1,3-dienes has been achieved which entails a sequential double olefination of 2-(arylmethylidene)-2-phosphonoacetonitriles by a one-pot domino process involving Michaeladdition of dimsyllithium to 2-(arylmethylidene)-2-phosphonoacetonitrile, Horner–Wadsworth–Emmons reaction of the resulting phosphonate ylide with the added aldehyde followed by base induced
Synthesis of cyclopent-1-enecarbonitriles <i>via</i> a tandem Giese/HWE reaction initiated by visible light
作者:Marek Moczulski、Dariusz Deredas、Elżbieta Kuśmierek、Łukasz Albrecht、Anna Albrecht
DOI:10.1039/d2cc06543f
日期:——
In the manuscript, a novel method for the preparation of cyclopent-1-enecarbonitriles viatandem Giese/HWE reactioninitiated by visible light in the presence of fac-Ir(ppy)3 as a photocatyst has been described. The cascade reactivity combining radical and polar processes has proven applicable for a wide range of N-(acyloxy)phthalimides (which serve as precursors of the corresponding radicals) as well