已开发出一种用于将多种简单和杂环芳烃与芳基碘化物、溴化物和氯化物进行分子内直接芳基化的催化剂。这些反应以极好的收率发生并且具有高度选择性。对芳基碘化物底物的研究表明,由于碘化物在反应介质中的积累,会发生催化剂中毒。这可以通过添加银盐来克服,银盐也允许这些反应在较低温度下发生。该方法的效用通过咔唑天然产物的快速合成和通过直接芳基化产物的开环反应合成空间位阻四邻位取代的联芳基来说明。机理研究提供了对催化剂的深入了解 s 作用模式并显示在钯催化的简单芳烃的直接芳基化中存在动力学上显着的 CH 键裂解。从这些研究中获得的知识导致了以前无法获得的芳烃的新分子间芳基化反应的发展,为其他新的直接芳基化过程的发展打开了大门。
Pd-Tetrahydrosalan-Type Complexes as Catalysts for Sonogashira Couplings in Water: Efficient Greening of the Procedure
作者:Krisztina Voronova、Levente Homolya、Antal Udvardy、Attila C. Bényei、Ferenc Joó
DOI:10.1002/cssc.201402147
日期:2014.8
diphenylacetylenes can be isolated in 76–98 % yield. The aqueous catalyst solution can be recycled four times with decreasing activity; however, yields between 93 and 98 % can still be achieved with extended reaction times. Several water‐insoluble products can be isolated in excellent yield by simple filtration and purification by washing with water; this method is used, for the first time, for this type
合成了新的磺化四氢salen型配体及其水溶性钯(II)配合物。钯(II)配合物催化各种芳基卤化物(包括氯代芳烃)与末端炔烃的Sonogashira偶联(23个实例),在温和条件下(80°C,空气,无Cu I助催化剂)在有机水溶液中具有良好至优异的转化率混合物和周转频率高达2790 h -1。在优化的反应条件下,以最小化环境污染,可以分离出76.98%的二苯乙炔。催化剂水溶液可以降低活性地循环使用四次。但是,延长反应时间仍可实现93%至98%的收率。通过简单的过滤和水洗纯化,可以分离出几种不溶于水的产物,收率很高。这种方法首次用于这种CC耦合过程。
Stereodivergent Alkyne Hydrofluorination Using Protic Tetrafluoroborates as Tunable Reagents
作者:Rui Guo、Xiaotian Qi、Hengye Xiang、Paul Geaneotes、Ruihan Wang、Peng Liu、Yi‐Ming Wang
DOI:10.1002/anie.202006278
日期:2020.9.14
available precursors remains a synthetic challenge. The metal‐free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These
Efficient palladium-catalyzed synthesis of substituted indoles employing a new (silanyloxyphenyl)phosphine ligand
作者:Christopher B. Lavery、Robert McDonald、Mark Stradiotto
DOI:10.1039/c2cc33071g
日期:——
The new and easily prepared OTips-DalPhos ligand (L1) offers broad substrate scope at relatively low loadings in the palladium-catalyzed C-N cross-coupling/cyclization of o-alkynylhalo(hetero)arenes with primary amines, affording indoles and related heterocyclic derivatives in high yield.
Visible Light‐Catalyzed Decarboxylative Alkynylation of Arenediazonium Salts with Alkynyl Carboxylic Acids: Direct Access to Aryl Alkynes by Organic Photoredox Catalysis
salts have been utilized as the aryl radical source to couple alkynyl carboxylic acids to feature the decarboxylative arylation. A wide range of substrates are amenable to this protocol with broad functional group tolerance, and diversely‐functionalized aryl alkynes could be synthesized undermild, neutral and transition metal‐free reaction conditions using visiblelight irradiation. Alongside synthetic