Predicting the Most Favored Path and the Overall Rate of Multistep: 2-Norbornyl Cation Rearrangements. The Assignment of a Trial Activation Energy for Each Unique Step

Abstract

Observable 2-norbornyl cations undergo at least five different rearrangement reactions, all of which are known from previous work on this system. In this paper, these rearrangement categories have been subdivided to reflect secondary–tertiary energy and rate differences and a trial set of activation free energies ΔG≠ is derived for each subdivided step. The most important of these parameters is the energy difference between secondary and tertiary (methyl) systems which was estimated as 5.5 kcal/mol. These parameters allow one, for the first time, to make a rational assessment of the overall reaction course of multistep rearrangement reactions in this system, for example, those observed in a number of bicyclo[2.2.1]heptyl(norbornyl) terpene systems.