C-C Cross-Couplings from a Cyclometalated Au(III) CN Complex: Mechanistic Insights and synthetic developments

Bonsignore, Riccardo, Thomas, Sophie R., Rigoulet, Mathilde, Jandl, Christian, Pöthig, Alexander, Bourissou, Didier, Barone, Giampaolo and Casini, Angela ORCID: https://orcid.org/0000-0003-1599-9542 2021. C-C Cross-Couplings from a Cyclometalated Au(III) CN Complex: Mechanistic Insights and synthetic developments. Chemistry - A European Journal 27 (57) , pp. 14322-14334. 10.1002/chem.202102668

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Abstract

In recent years, the reactivity of gold complexes was shown to extend well beyond π-activation and to hold promises to achieve selective cross-couplings in several C−C and C−E (E=heteroatom) bond forming reactions. Here, with the aim of exploiting new organometallic species for cross-coupling reactions, we report on the Au(III)-mediated C(sp2)−C(sp) occurring upon reaction of the cyclometalated complex [Au(CCH2N)Cl2] (1, CCH2N=2-benzylpyridine) with AgPhCC. The reaction progress has been monitored by NMR spectroscopy, demonstrating the involvement of a number of key intermediates, whose structures have been unambiguously ascertained through 1D and 2D NMR analyses (1H, 13C, 1H-1H COSY, 1H-13C HSQC and 1H-13C HMBC) as well as by HR-ESI-MS and X-ray diffraction studies. Furthermore, crystallographic studies have serendipitously resulted in the authentication of zwitterionic Au(I) complexes as side-products arising from cyclization of the coupling product in the coordination sphere of gold. The experimental work has been paralleled and complemented by DFT calculations of the reaction profiles, providing valuable insight into the structure and energetics of the key intermediates and transition states, as well as on the coordination sphere of gold along the whole process. Of note, the broader scope of the cross-coupling at the Au(III) CCH2N centre has also been demonstrated studying the reaction of 1 with C(sp2)-based nucleophiles, namely vinyl and heteroaryl tin and zinc reagents. These reactions stand as rare examples of C(sp2)−C(sp2) cross-couplings at Au(III).

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Additional Information:	This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Publisher:	Wiley
ISSN:	0947-6539
Funders:	EPSRC
Date of First Compliant Deposit:	9 November 2021
Date of Acceptance:	26 July 2021
Last Modified:	05 Jan 2024 07:44
URI:	https://orca.cardiff.ac.uk/id/eprint/145384

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