Manganese-Catalyzed Cross-Coupling of Aryl Halides and Grignard Reagents by a Radical Mechanism
作者:Giuseppe Antonacci、Andreas Ahlburg、Peter Fristrup、Per-Ola Norrby、Robert Madsen
DOI:10.1002/ejoc.201700981
日期:2017.9.1
of side products. A broader scope was observed for the Grignard reagents where a variety of alkyl- and arylmagnesium chlorides participated in the coupling. Two radical clock experiments were performed which in both cases succeeded in trapping an intermediate aryl radical. The cross coupling is therefore believed to proceed by a SRN1 mechanism, where a triorganomanganate complex serves as the most
研究了MnCl2催化芳基卤化物与格氏试剂交叉偶联反应的底物范围和机理。当芳基卤化物是在对位含有氰基或酯基或在邻位含有氰基的氯化物时,转化进行迅速且产率良好。一系列其他取代基没有产生芳基卤化物的转化或导致副产物的形成。对于格氏试剂,观察到更广泛的范围,其中各种烷基氯化镁和芳基氯化镁参与了偶联。进行了两个自由基时钟实验,在这两种情况下都成功地捕获了中间芳基自由基。因此,交叉耦合被认为是通过 SRN1 机制进行的,其中三有机锰酸盐配合物最有可能是亲核试剂和单电子供体。根据芳基卤化物的底物范围,排除了其他机械方案。