Rate and Equilibrium Constants for the Addition of N-Heterocyclic Carbenes into Benzaldehydes: A Remarkable 2-Substituent Effect

Collett, C.J.; Massey, R.S.; Taylor, J.E.; Maguire, O.R.; O'Donoghue, A.C.; Smith, A.D.

doi:10.1002/anie.201501840

Rate and Equilibrium Constants for the Addition of N-Heterocyclic Carbenes into Benzaldehydes: A Remarkable 2-Substituent Effect

Collett, C.J.; Massey, R.S.; Taylor, J.E.; Maguire, O.R.; O'Donoghue, A.C.; Smith, A.D.

Authors

C.J. Collett

R.S. Massey

J.E. Taylor

O.R. Maguire

Professor Ann O'Donoghue annmarie.odonoghue@durham.ac.uk
Professor

A.D. Smith

Abstract

Rate and equilibrium constants for the reaction between N-aryl triazolium N-heterocyclic carbene (NHC) precatalysts and substituted benzaldehyde derivatives to form 3-(hydroxybenzyl)azolium adducts under both catalytic and stoichiometric conditions have been measured. Kinetic analysis and reaction profile fitting of both the forward and reverse reactions, plus onwards reaction to the Breslow intermediate, demonstrate the remarkable effect of the benzaldehyde 2-substituent in these reactions and provide insight into the chemoselectivity of cross-benzoin reactions.

Citation

Collett, C., Massey, R., Taylor, J., Maguire, O., O'Donoghue, A., & Smith, A. (2015). Rate and Equilibrium Constants for the Addition of N-Heterocyclic Carbenes into Benzaldehydes: A Remarkable 2-Substituent Effect. Angewandte Chemie International Edition, 54(23), 6887-6892. https://doi.org/10.1002/anie.201501840

Journal Article Type	Article
Online Publication Date	Apr 23, 2015
Publication Date	Jun 1, 2015
Deposit Date	Oct 22, 2015
Publicly Available Date	Oct 28, 2015
Journal	Angewandte Chemie International Edition
Print ISSN	1433-7851
Electronic ISSN	1521-3773
Publisher	Wiley
Peer Reviewed	Peer Reviewed
Volume	54
Issue	23
Pages	6887-6892
DOI	https://doi.org/10.1002/anie.201501840
Keywords	2-substituent effect, Kinetics, Mechanistic studies, N-heterocyclic carbenes, Organocatalysis.

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© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.