Ag(I)-Catalyzed C–H Activation: The Role of the Ag(I) Salt in Pd/Ag-Mediated C–H Arylation of Electron-Deficient Arenes
† School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
‡ Imperial College London, Department of Chemistry Exhibition Road, South Kensington, SW7 2AZ, London, U.K.
J. Am. Chem. Soc., 2016, 138 (27), pp 8384–8387
DOI: 10.1021/jacs.6b04726
Publication Date (Web): June 15, 2016
Copyright © 2016 American Chemical Society
Abstract
The use of stoichiometric Ag(I)-salts as additives in Pd-catalyzed C–H functionalization reactions is widespread.
It is commonly proposed that this additive acts as an oxidant or as a halide scavenger promoting Pd-catalyst turnover. We demonstrate that, contrary to current proposals, phosphine ligated Ag(I)-carboxylates can efficiently carry out C–H activation on electron-deficient arenes.
We show through a combination of stoichiometric and kinetic studies that a (PPh3)Ag-carboxylate is responsible for the C–H activation step in the Pd-catalyzed arylation of Cr(CO)3-complexed fluorobenzene.
Furthermore, the reaction rate is controlled by the rate of Ag(I)-C–H activation, leading to an order zero on the Pd-catalyst. H/D scrambling studies indicate that this Ag(I) complex can carry out C–H activation on a variety of aromatic compounds traditionally used in Pd/Ag-mediated C–H functionalization methodologies.
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/jacs.6b04726.
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