Mechanistic Study of the Copper(II)-Mediated Site-Selective <i>O</i>-Arylation of Glycosides with Arylboronic Acids
Sofia Jdanova, Mark S. Taylor
Abstract
-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.
Topics & Concepts
TransmetalationChemistrySubstituentBoronic acidIntramolecular forceArylCopperGlycosideCombinatorial chemistryOrganic chemistryMedicinal chemistryCatalysisAlkylCarbohydrate Chemistry and SynthesisCatalytic Cross-Coupling ReactionsLegume Nitrogen Fixing Symbiosis