Unravelling the mechanism of cobalt-catalysed remote C-H nitration of 8-aminoquinolinamides and expansion of substrate scope towards 1-naphthylpicolinamide

CHU, Melody, PLANAS, Oriol, COMPANY, Anna, RIBAS, Xavi, HAMILTON, Alex and WHITEOAK, Christopher (2019). Unravelling the mechanism of cobalt-catalysed remote C-H nitration of 8-aminoquinolinamides and expansion of substrate scope towards 1-naphthylpicolinamide. Chemical Science.

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Official URL: https://pubs.rsc.org/en/Content/ArticleLanding/201...
Open Access URL: https://pubs.rsc.org/en/content/articlepdf/2019/sc... (Published)
Link to published version:: https://doi.org/10.1039/c9sc05076k

Abstract

Previously, an unexpected Co-catalysed remote C-H nitration of 8-aminoquinolinamide compounds was developed. This report provided a novel reactivity for Co and was assumed to proceed through the mechanistic pathway already known for analogous Cu-catalysed remote couplings of the same substrates. In order to shed light into this intriguing, and previously unobserved reactivity for Co, a thorough computational study has now been performed, which has allowed for a full understanding of the operative mechanism. This study demonstrates that the Co-catalysed remote coupling does not occur through the previously proposed Single Electron Transfer (SET) mechanism, but actually operates through a High-Spin Induced Remote Radical Coupling mechanism, through a key intermediate with significant proportion of spin density at the 5- and 7-positions of the aminoquinoline ring. Additionally, new experimental data provides expansion of the synthetic utility of the original nitration procedure towards 1-naphthylpicolinamide which unexpectedly appears to operate via a subtly different mechanism despite having a similar chelate environment.

Item Type: Article
Uncontrolled Keywords: 03 Chemical Sciences
Identification Number: https://doi.org/10.1039/c9sc05076k
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 27 Nov 2019 12:35
Last Modified: 09 Dec 2019 12:15
URI: http://shura.shu.ac.uk/id/eprint/25491

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