Issue 37, 2023

Ortho-Selective amination of arene carboxylic acids via rearrangement of acyl O-hydroxylamines

Abstract

Direct amination of arene C–H bonds is an attractive disconnection to form aniline-derived building blocks. This transformation presents significant practical challenges; classical methods for ortho-selective amination require strongly acidic or forcing conditions, while contemporary catalytic processes often require bespoke directing groups and/or precious metal catalysis. We report a mild and procedurally straightforward ortho-selective amination of arene carboxylic acids, arising from a facile rearrangement of acyl O-hydroxylamines without requiring precious metal catalysts. A broad scope of benzoic acid substrates are compatible and the reaction can be applied to longer chain arene carboxylic acids. Mechanistic studies probe the specific requirement for trifluoroacetic acid in generating the active aminating agent, and suggest that two separate mechanisms may be operating in parallel in the presence of an iron catalyst: (i) an iron-nitrenoid intermediate and (ii) a radical chain pathway. Regardless of which mechanism is followed, high ortho selectivity is obtained, proposed to arise from the directivity (first) or attractive interactions (second) arising with the carboxylic acid motif.

Graphical abstract: Ortho-Selective amination of arene carboxylic acids via rearrangement of acyl O-hydroxylamines

Supplementary files

Article information

Article type
Edge Article
Submitted
28 6 2023
Accepted
17 8 2023
First published
18 8 2023
This article is Open Access

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

Chem. Sci., 2023,14, 10103-10111

Ortho-Selective amination of arene carboxylic acids via rearrangement of acyl O-hydroxylamines

J. E. Gillespie, N. Y. S. Lam and R. J. Phipps, Chem. Sci., 2023, 14, 10103 DOI: 10.1039/D3SC03293K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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