"The effect of conformation on reactivity is intimately associated with the details of the mechanism of a reaction. ... As a warning against predicting product stereochemistry based on reactant conformation, the Curtin-Hammett principle states that the rate of reaction of a molecule is a function not only of the concentration of any reacting conformation but also of its transition state energy. … The conformational barrier (A <=> B) is substantially higher than the reaction barriers TSA and TSB. This case is known as the conformational equilibrium control, where the ratio of products is equal to the ratio of the population of the starting states."