Homocoupling-free iron-catalysed twofold C-H activation/cross-couplings of aromatics via transient connection of reactants
Homocoupling-free iron-catalysed twofold C-H activation/cross-couplings of aromatics via transient connection of reactants
复制标题
DOI：
10.1038/s41929-019-0245-3
复制
发表时间：
2019-05-01
期刊：
影响因子：
37.8
通讯作者：
Nakamura, Eiichi
中科院分区：
文献类型：
--
作者：
Doba, Takahiro;Matsubara, Tatsuaki;Nakamura, Eiichi
化学计量比的有机分子R-1-H和R-2-H的双重C-H活化/交叉偶联，形成无同偶联产物的R-1-R-2产物是非活性C-H键活化的目标，因为这将极大地简化有机合成。在不使用过量反应物的情况下有效消除同系偶联副产物的可靠策略是已知的。在这里，我们报告了两个反应物通过添加到一个反应物上的阴离子基团的瞬时连接，在温和的氧化铁催化的条件下，通过形成有效的异构体R-1-M-R-2来实现这一目标。我们使用N-(喹啉-8-基)酰胺阴离子进行临时连接，并以高产率交叉偶联化学计量比的芳烃混合物，而没有任何同偶联物的痕迹。几种给体/受体的噻吩类化合物和碳/硫桥连的平面共轭体系的短步合成说明了该方法在有机合成中的应用。
Twofold C-H activation/cross-coupling of stoichiometric amounts of organic molecules, R-1-H and R-2-H, to form an R-1-R-2 product free of homocoupling products is a goal in the activation of unreactive C-H bonds, as it will dramatically simplify organic synthesis. No reliable strategy to eliminate the homocoupling side products effectively without recourse to the use of an excess of one reactant over another is known. We report herein that a transient connection of two reactants by an anionic group appended to one reactant achieves this goal under mildly oxidative iron-catalysed conditions, through the formation of a productive heteroleptic R-1-M-R-2 intermediate. We utilized an N-(quinolin-8-yl)amide anion for the temporary connection and cross-coupled a stoichiometric mixture of aromatics in high yield without any trace of homocoupling products. A short-step synthesis of several donor/acceptor thiophene compounds and carbon/sulfur-bridged flat conjugated systems illustrates the utility of this method to streamline organic synthesis.