Mechanistic Study of the Copper(II)-Mediated Site-Selective O‑Arylation of Glycosides with Arylboronic Acids

Glycosides having multiple free OH groups have been shown to undergo site-selective O-arylations in the presence of arylboronic acids and copper­(II) acetate. Herein, a mechanistic analysis of these Chan–Evans–Lam-type couplings is presented based on reaction kinetics, mass spectrometric analysis of...

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Bibliographic Details
Published in:Journal of organic chemistry 2023-03, Vol.88 (6), p.3487-3498
Main Authors: Jdanova, Sofia, Taylor, Mark S.
Format: Article
Language:English
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Summary:Glycosides having multiple free OH groups have been shown to undergo site-selective O-arylations in the presence of arylboronic acids and copper­(II) acetate. Herein, a mechanistic analysis of these Chan–Evans–Lam-type couplings is presented based on reaction kinetics, mass spectrometric analysis of reaction mixtures, and substituent effect studies. The results establish that the formation of a substrate-derived boronic ester accelerates the rate-determining transmetalation step. Intramolecular transfer of the aryl group from the boronic ester is ruled out in favor of a pathway in which the key pre-transmetalation assembly is generated from a boronic ester, a copper complex, and a second equivalent of arylboronic acid.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.2c02693