Panigrahi Adyasha, Whitaker Daniel, Vitorica-Yrezabal Iñigo J, Larrosa Igor
School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
ACS Catal. 2020 Feb 7;10(3):2100-2107. doi: 10.1021/acscatal.9b05334. Epub 2020 Jan 9.
Diverse C-H functionalizations catalyzed by Pd employ Ag(I) salts added as halide abstractors or oxidants. Recent reports have shown that Ag can also perform the crucial C-H activation step in several of these functionalizations. However, all of these processes are limited by the wasteful requirement for (super)stoichiometric Ag(I) salts. Herein, we report the development of a Ag/Pd cocatalyzed direct arylation of (fluoroarene) chromium tricarbonyl complexes with bromoarenes. The small organic salt, NMeOC(CF), added as a halide abstractor, enables the use of a catalytic amount of Ag, reversing the rapid precipitation of AgBr. We have shown through H/D scrambling and kinetic studies that a (PR)Ag-alkoxide is responsible for C-H activation, a departure from previous studies with Ag carboxylates. Furthermore, the construction of biaryls directly from the simple arene is achieved via a one-pot chromium tricarbonyl complexation/C-H arylation/decomplexation sequence using (pyrene)Cr(CO) as a Cr(CO) donor.
钯催化的多种碳氢键官能团化反应使用添加的银（I）盐作为卤化物萃取剂或氧化剂。最近的报道表明，银在其中一些官能团化反应中也能进行关键的碳氢键活化步骤。然而，所有这些过程都受到对（超）化学计量的银（I）盐的浪费性需求的限制。在此，我们报道了一种银/钯共催化的（氟代芳烃）三羰基铬配合物与溴代芳烃的直接芳基化反应的开发。作为卤化物萃取剂添加的小有机盐NMeOC（CF），使得能够使用催化量的银，从而避免了溴化银的快速沉淀。我们通过氢/氘交换和动力学研究表明，（PR）Ag-醇盐负责碳氢键活化，这与之前使用羧酸银的研究不同。此外，使用（芘）Cr（CO）作为Cr（CO）供体，通过一锅法的三羰基铬配合化/碳氢键芳基化/脱配合化序列，直接从简单芳烃构建联芳基。
