Rovira Mireia, Jašíková Lucie, Andris Erik, Acuña-Parés Ferran, Soler Marta, Güell Imma, Wang Ming-Zheng, Gómez Laura, Luis Josep M, Roithová Jana, Ribas Xavi
Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, E-17003 Girona, Catalonia, Spain.
Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43 Prague 2, Czech Republic.
Chem Commun (Camb). 2017 Aug 11;53(62):8786-8789. doi: 10.1039/c7cc04491g. Epub 2017 Jul 21.
Unraveling the mechanistic details of copper-catalyzed arylation of nucleophiles (Ullmann-type couplings) is a very challenging task. It is a matter of intense debate whether it is a radical-based process or an organometallic redox-based process. The ancillary ligand choice in Ullmann-type couplings plays a key role in such transformations and can strongly influence the catalytic efficiency as well as the mechanism. Here, we show how a predesigned tridentate pincer-like catalyst undergoes a deactivation pathway through a Cu/Cu prototypical mechanism as demonstrated by helium-tagging infrared photodissociation (IRPD) spectroscopy and DFT studies, lending a strong support to the existence of an aryl-Cu species in the Ullmann couplings using this tridentate ligand.
阐明铜催化亲核试剂芳基化反应（乌尔曼型偶联反应）的机理细节是一项极具挑战性的任务。该反应是基于自由基的过程还是基于有机金属氧化还原的过程，这是一个激烈争论的问题。在乌尔曼型偶联反应中，辅助配体的选择在这类转化中起着关键作用，并且会强烈影响催化效率以及反应机理。在此，我们展示了一种预先设计的三齿钳形催化剂如何通过铜/铜原型机制经历失活途径，这一过程由氦标记红外光解离（IRPD）光谱和密度泛函理论（DFT）研究证明，有力地支持了在使用这种三齿配体的乌尔曼偶联反应中存在芳基 - 铜物种。
