Cowie Rosalyne M, Turega Simon M, Philp Douglas
EaStCHEM and Centre for Biomolecular Sciences, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
Org Lett. 2006 Nov 9;8(23):5179-82. doi: 10.1021/ol061290c.
[Structure: see text] A simple receptor and substrate are used to probe the relationship between transition-state charge and the level of rate acceleration that can be created by stabilizing the transition state through hydrogen bonding. Pericyclic reactions are accelerated less than 2-fold by the receptor, whereas a conjugate addition reaction is accelerated more than 30-fold. Therefore, substrate polarization by hydrogen bonding would only appear to be effective for reactions that generate significant charge at the transition state.
