Palladium-Catalyzed Asymmetric Intramolecular Dearomative Heck Reaction of Pyrrole Derivatives
作者:Ping Yang、Shu-Li You
DOI:10.1021/acs.orglett.8b03425
日期:2018.12.7
The Pd-catalyzed asymmetric intramolecular dearomatization of pyrroles via the Heck reaction in the presence of commercially available Pd(OAc)2 and the Feringa ligand is described. Diverse pyrroline derivatives were obtained in excellent yields (up to 99%) with high enantioselectivity (up to 96% ee). The reaction features a wide substrate scope, relatively mild conditions, and useful transformations
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。
Metallic nickel-mediated synthesis of ketones by the reaction of benzylic, allylic, vinylic, and pentafluorophenyl halides with acid halides
Copper-Catalyzed Chemodivergent Cyclization of N-(<i>ortho</i>-alkynyl)aryl-Pyrrole and Indoles
作者:Tengfei Yao、Tong Xia、Wei Yan、Haofeng Xu、Fang Zhang、Yuanjing Xiao、Junliang Zhang、Lu Liu
DOI:10.1021/acs.orglett.0c01519
日期:2020.6.5
Herein, we described an efficient copper-catalyzed chemo-divergent tandem reaction of N-(ortho-alkynyl)aryl-pyrrole and (iso)indoles, delivering ring-fused N-heterocycles in good yields in an atom-economical manner. N-(ortho-alkynyl)aryl-pyrrole and indoles undergo the tandem cyclization/migration reaction, in which the group at 2-position was migrated to 3-position. In contrast, the dearomative cyclization of N-(ortho-alkynyl)aryl-isoindoles would occur to deliver the N-fused tetracyclic products efficiently.