Type-I dyotropic rearrangement for 1,2-disubstituted cyclohexanes: substitution effect on activation energy

Abstract

For an array of judiciously selected 1,2-disubstituted cyclohexane motifs, the migratory aptitude and contribution of specific structural features of synthetically valuable functional groups and halogen atoms in type-I dyotropic rearrangement are reported by employing quantum chemical calculations. This double migration process requires higher activation barriers for carbon, silicon and nitrogen bearing substituents, however, it is thermally allowed and a feasible approach for several important moieties including oxygen, sulphur, phosphorous and halogen atoms bearing migrating fragments. Strong positive correlations are observed by plotting representative activation energy trends against inductive sigma (σ_I), field (σ_F), steric substituent (E_s) and polar substituent (σ*) constants. Also, an effect of the asymmetric combinations of substituents is presented which provides an interesting insight into such substitution patterns.