Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi , E-17003 Girona, Catalonia, Spain.
Serveis Tècnics de Recerca (STR), Universitat de Girona, Parc Científic i Tecnològic de la UdG , Pic de Peguera 15, E17003 Girona, Catalonia, Spain.
J Org Chem. 2016 Sep 2;81(17):7315-25. doi: 10.1021/acs.joc.6b01035. Epub 2016 Jun 9.
The copper-catalyzed arylation of nucleophiles has been established as an efficient methodology for the formation of C-C and C-heteroatom bonds. Considering the advances during the last two decades, the ligand choice plays a key role in such transformations and can strongly influence the catalytic efficiency. The applicability of these Ullmann-type coupling reactions regarding the orthogonal selectivity of different functional groups constitutes a challenging subject for current synthetic strategies. Herein, we report a useful toolkit of Cu-based catalysts for the chemoselective arylation of a wide-range of nucleophiles in competitive reactions using aryl iodides and bromides. We show in this work that the arylation of all kinds of amides can be orthogonal to that of amines (aliphatic or aromatic) and phenol derivatives. This high chemoselectivity can be governed by the use of different ligands, yielding the desired coupling products under mild conditions. The selectivity trends are maintained for electronically biased iodobenzene and bromobenzene electrophiles. Radical clock experiments discard the occurrence of radical-based mechanisms.
铜催化亲核试剂的芳基化已被确立为形成 C-C 和 C-杂原子键的有效方法。考虑到过去二十年的进展，配体选择在这些转化中起着关键作用，并可以强烈影响催化效率。这些 Ullmann 型偶联反应在不同官能团的正交选择性方面的适用性是当前合成策略的一个具有挑战性的课题。在此，我们报告了一种有用的基于 Cu 的催化剂工具箱，用于在使用芳基碘化物和溴化物的竞争反应中对各种亲核试剂进行化学选择性芳基化。我们在这项工作中表明，各种酰胺的芳基化可以与脂肪族或芳香族胺和苯酚衍生物的芳基化正交。通过使用不同的配体，可以实现这种高化学选择性，在温和的条件下得到所需的偶联产物。选择性趋势对于电子偏向的碘苯和溴苯亲电试剂保持不变。自由基钟实验排除了自由基机理的发生。
