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Rate and Equilibrium Constants for the Addition of N‐Heterocyclic Carbenes into Benzaldehydes: A Remarkable 2‐Substituent Effect
Author(s) -
Collett Christopher J.,
Massey Richard S.,
Taylor James E.,
Maguire Oliver R.,
O'Donoghue AnnMarie C.,
Smith Andrew D.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201501840
Subject(s) - benzaldehyde , chemistry , substituent , benzoin , carbene , reaction rate constant , stoichiometry , catalysis , chemoselectivity , medicinal chemistry , reaction rate , adduct , aryl , organic chemistry , computational chemistry , alkyl , kinetics , physics , quantum mechanics
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.