The kinetic and thermodynamic influence of fluorine versus methyl substituents in methylenecyclopropane rearrangements

A comprehensive review of the kinetic and thermodynamic influences of methyl and fluorine substituents on the methylenecyclopropane rearrangement is presented. In spite of a superficial similarity of the overall influence of these two substituents, methyl's effect derives largely from the incremental nature of its radical- and alkene-stabilizing, and steric impact, while fluorine's effect derives from its large and non-incremental influence on the strain of cyclopropane coupled with its similarly variable effect on the stability of alkenes and free radicals.