Issue 36, 2019

Oxidant speciation and anionic ligand effects in the gold-catalyzed oxidative coupling of arenes and alkynes

Abstract

The mechanism of the gold-catalyzed oxidative cross-coupling of arenes and alkynes has been studied in detail combining stoichiometric experiments with putative reaction intermediates and DFT calculations. Our data suggest that ligand exchange between the alkyne, the Au(I)-catalyst and the hypervalent iodine reagent is responsible for the formation of both an Au(I)-acetylide complex and a more reactive “non-symmetric” I(III) oxidant responsible for the crucial Au(I)/Au(III) turnover. Further, the reactivity of the in situ generated Au(III)-acetylide complex is governed by the nature of the anionic ligands transferred by the I(III) oxidant: while halogen ligands remain unreactive, acetato ligands are efficiently displaced by the arene to yield the observed Csp2–Csp cross-coupling products through an irreversible reductive elimination step. Finally, the nature of competitive processes and catalyst deactivation pathways has also been unraveled. This detailed investigation provides insights not only on the specific features of the species involved in oxidative gold-catalyzed cross couplings but also highlights the importance of both ancillary and anionic ligands in the reactivity of the key Au(III) intermediates.

Graphical abstract: Oxidant speciation and anionic ligand effects in the gold-catalyzed oxidative coupling of arenes and alkynes

Supplementary files

Article information

Article type
Edge Article
Submitted
15 5 2019
Accepted
09 7 2019
First published
31 7 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 8411-8420

Oxidant speciation and anionic ligand effects in the gold-catalyzed oxidative coupling of arenes and alkynes

M. Hofer, T. de Haro, E. Gómez-Bengoa, A. Genoux and C. Nevado, Chem. Sci., 2019, 10, 8411 DOI: 10.1039/C9SC02372K

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