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.

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.
• Public URL: https://durham-repository.worktribe.com/output/1397081