methods that address the selective formation of (Z)-olefins. In such cases, specific catalysts (e. g., cross-metathesis)3 or modified anion stabilizing groups (e. g., Still-Gennari modification of Horner-Wadsworth-Emmonsolefination)4 are utilized. The Peterson olefination,2g, 2h on the other hand, allows for the stereoselective formation of either (E) or (Z)-olefins from the same starting material by a
介绍 碳-碳键形成反应是有机合成化学中的关键连接反应。其中,不饱和键(特别是烯烃)的立体选择性形成具有重要意义,因为它们参与天然产物、生物活性化合物和材料的合成。目前,实现立体选择性连接烯化的两种常用方法是烯烃交叉复分解1和阴离子稳定试剂与醛或酮的偶联2(图 1)。这些方法通常在温和的反应条件下进行,对官能团表现出良好的耐受性,并且主要产生( E )-构型的烯烃。然而,解决( Z )-烯烃的选择性形成的方法有限。在这种情况下,使用特定的催化剂(例如交叉复分解)3或改性阴离子稳定基团(例如Horner-Wadsworth-Emmons烯化的Still-Gennari改性)4 。另一方面,Peterson 烯化(2g,2h)允许通过反应后处理(酸性与碱性)的简单改变,从相同的起始材料立体选择性地形成( E)或(Z )-烯烃。 5然而,即使在这种情况下,原位生成的加合物 (顺/反)的立体选择性也反映在烯化反应的最终立体化学结果中。
Modular Solid-Phase Synthesis of Teroxazoles as a Class of α-Helix Mimetics
作者:Cristiano Pinto Gomes、Alexander Metz、Jan W. Bats、Holger Gohlke、Michael W. Göbel
DOI:10.1002/ejoc.201200339
日期:2012.6
modular solid-phase synthesis of teroxazole derivatives as a new class of α-helixmimetics. The synthesis is compatible with a variety of functional groups and should thus be generally applicable for generating diversely substituted oligo-oxazole scaffolds. The teroxazole scaffold is predicted to be polar and to project peptidomimetic side chains at positions i, i+3, and i+6 of an α-helix, which complements