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Article

Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et3SiH/KOtBu

Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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Authors to whom correspondence should be addressed.
Academic Editor: Rafał Loska
Molecules 2021, 26(22), 6879; https://doi.org/10.3390/molecules26226879
Received: 13 October 2021 / Revised: 3 November 2021 / Accepted: 5 November 2021 / Published: 15 November 2021
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. View Full-Text
Keywords: Truce–Smiles rearrangement; Grubbs–Stoltz reagent; radical; electron transfer; aryl substitution; diarylmethanes; dihydroacridines; triethylsilane; potassium tert-butoxide; DFT; carbanion Truce–Smiles rearrangement; Grubbs–Stoltz reagent; radical; electron transfer; aryl substitution; diarylmethanes; dihydroacridines; triethylsilane; potassium tert-butoxide; DFT; carbanion
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MDPI and ACS Style

Kolodziejczak, K.; Stewart, A.J.; Tuttle, T.; Murphy, J.A. Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et3SiH/KOtBu. Molecules 2021, 26, 6879. https://doi.org/10.3390/molecules26226879

AMA Style

Kolodziejczak K, Stewart AJ, Tuttle T, Murphy JA. Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et3SiH/KOtBu. Molecules. 2021; 26(22):6879. https://doi.org/10.3390/molecules26226879

Chicago/Turabian Style

Kolodziejczak, Krystian, Alexander J. Stewart, Tell Tuttle, and John A. Murphy 2021. "Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et3SiH/KOtBu" Molecules 26, no. 22: 6879. https://doi.org/10.3390/molecules26226879

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