Radical and ionic mechanisms in rearrangements of o-tolyl aryl ethers and amines initiated by the Grubbs–Stoltz reagent, Et3SiH/KOtBu

Kolodziejczak, K., Stewart, A. J., Tuttle, T. and Murphy, J. A. (2021) Radical and ionic mechanisms in rearrangements of o-tolyl aryl ethers and amines initiated by the Grubbs–Stoltz reagent, Et3SiH/KOtBu. Molecules, 26(22), 6879. (doi: 10.3390/molecules26226879) (PMID:34833971) (PMCID:PMC8619283)

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Rearrangements of o-tolyl aryl ethers, amines, and sulfides with the Grubbs–Stoltz reagent (Et3SiH + KOtBu) were recently announced, in which the ethers were converted to o-hydroxydiarylmethanes, while the (o-tol)(Ar)NH amines were transformed into dihydroacridines. Radical mechanisms were proposed, based on prior evidence for triethylsilyl radicals in this reagent system. A detailed computational investigation of the rearrangements of the aryl tolyl ethers now instead supports an anionic Truce–Smiles rearrangement, where the initial benzyl anion can be formed by either of two pathways: (i) direct deprotonation of the tolyl methyl group under basic conditions or (ii) electron transfer to an initially formed benzyl radical. By contrast, the rearrangements of o-tolyl aryl amines depend on the nature of the amine. Secondary amines undergo deprotonation of the N-H followed by a radical rearrangement, to form dihydroacridines, while tertiary amines form both dihydroacridines and diarylmethanes through radical and/or anionic pathways. Overall, this study highlights the competition between the reactive intermediates formed by the Et3SiH/KOtBu system.

Item Type:Articles
Additional Information:The authors thank the University of Strathclyde for funding and the EPSRC-funded ARCHIE-WeSt High Performance Computer (www.archie-west.ac.uk, accessed on 13 October 2021) for computational resource via EPSRC grant no. EP/K000586/1.
Glasgow Author(s) Enlighten ID:Murphy, Professor John
Creator Roles:
Murphy, J. A.Conceptualization, Data curation, Funding acquisition, Supervision, Writing – review and editing
Authors: Kolodziejczak, K., Stewart, A. J., Tuttle, T., and Murphy, J. A.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Molecules
ISSN (Online):1420-3049
Published Online:15 November 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Molecules 26(22): 6879
Publisher Policy:Reproduced under a Creative Commons License

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