Amaya Toru, Hata Dai, Moriuchi Toshiyuki, Hirao Toshikazu
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871 (Japan).
Chemistry. 2015 Nov 9;21(46):16427-33. doi: 10.1002/chem.201501969. Epub 2015 Oct 6.
A reduced form of polyaniline has been shown to induce direct arylation of an arenediazonium salt with an arene (Gomberg-Bachmann reaction) to give the cross-coupling product in moderate to good yields under mild conditions. Various arenediazonium salts and arenes, including heteroarenes such as furans, thiophenes, and pyrroles, are employed for the reaction. The most favorable combination of substrates is an electron-poor arenediazonium salt with an electron-rich heteroarene. Investigation of the mechanism by reactions with radical scavengers and experiments on kinetic isotope effects indicated the occurrence of a radical chain reaction initiated by one-electron reduction of an arenediazonium salt by the polyaniline. Only 1 mol % (based on aniline tetramer) of the polyaniline is required for the cross-coupling reaction to occur. This reaction proceeds under metal-free conditions and with no need for photonic activation.
已表明一种还原形式的聚苯胺能在温和条件下诱导芳基重氮盐与芳烃发生直接芳基化反应（贡伯格 - 巴赫曼反应），以中等至良好的产率得到交叉偶联产物。各种芳基重氮盐和芳烃，包括呋喃、噻吩和吡咯等杂芳烃，都可用于该反应。最有利的底物组合是缺电子的芳基重氮盐与富电子的杂芳烃。通过与自由基清除剂反应对反应机理进行研究以及动力学同位素效应实验表明，该反应是由聚苯胺对芳基重氮盐进行单电子还原引发的自由基链反应。交叉偶联反应发生仅需1 mol%（基于苯胺四聚体）的聚苯胺。该反应在无金属条件下进行，无需光活化。
