Probing the limits of rate acceleration mediated by hydrogen bonds.
[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.
Cowie
Rosalyne M
RM
EaStCHEM and Centre for Biomolecular Sciences, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
Turega
Simon M
SM
Philp
Douglas
D
D006860:Hydrogen Bonding; D007700:Kinetics; D008301:Maleimides / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure
D008301:Maleimides; C043592:maleimide