Mm. Davidson et al., CONFORMATIONAL AND SOLVATION ASPECTS OF THE CHORISMATE-PREPHENATE REARRANGEMENT STUDIED BY AB-INITIO ELECTRONIC-STRUCTURE AND SIMULATION METHODS, Perkin transactions. 2, (7), 1997, pp. 1395-1400
The effect of water on the energetics of the Claisen rearrangement of
chorismate to prephenate has been investigated with both a continuum m
odel(PCM) and explicit solvation within a Monte Carlo (MC) free energy
perturbation (FEP) treatment, Both models are surprisingly similar in
their quantitative predictions, Solvation is shown to increase the co
nformational flexibility in the reactant by reducing the energy differ
ence between the diequatorial and diaxial structures, and to lead to a
considerable reduction in the barrier to the reaction, The estimate o
f the activation barrier, 22 kcal mol(-1),dagger is very close to the
experimental value of 24.5 kcal mol(-1). The implications of the vario
us possible conformers on kinetic isotope effects are discussed.