Stereoselective Tandem Ring Opening of Imidazoles with Electron-Deficient Acetylenes and Water: Synthesis of Functionalized (<i>Z</i>,<i>Z</i>)-1,4-Diaza-2,5-dienes
作者:Boris A. Trofimov、Ludmila V. Andriyankova、Lina P. Nikitina、Kseniya V. Belyaeva、Anastasia G. Mal’kina、Lubov N. Sobenina、Andrei V. Afonin、Igor A. Ushakov
DOI:10.1021/ol400844x
日期:2013.5.3
1-Substituted imidazoles undergo exceptionally facile stereoselective ring opening under the influence of electron-deficient acetylenes and water (equimolar ratio of the reactants) in MeCN at 45–60 °C without any catalysts to afford functionalized (Z,Z)-1,4-diaza-2,5-dienes, (Z,Z)-propenylaminoethenylformamides, in up to 80% yields. The reaction is rationalized to proceed in a tandem manner via zwitterionic
1-取代的咪唑在45-60°C的MeCN中,在缺电子的乙炔和水(反应物的等摩尔比)的影响下,特别容易发生立体选择性开环,而没有任何催化剂可提供官能化的(Z,Z)-1,4 -重氮-2,5-二烯,(Z,Z)-丙烯基氨基乙烯基甲酰胺,产率高达80%。通过将咪唑亲核加成至三键而形成的两性离子乙烯基碳负离子,使该反应合理地以串联方式进行。然后用水将碳负离子中心淬灭,然后重排中间的2-羟基-3-烯基咪唑啉。