Methylenecyclopropanes in Elimination and Addition Reactions: Quantification of the Effects of Strain

Abstract

The effect of strain in 1,2-elimination reactions that form methylenecyclopropanes has been evaluated for a series of leaving groups. The worse the leaving group, the greater is the inhibitory effect of strain build-up, which reaches 50% of the excess enthalpy differential for the poorest leaving group studied. In nucleophilic addition to an electrophilic methylenecyclopropane, comparison of strained and unstrained systems shows that about 60% of the excess enthalpy differential promotes the reactivity of the strained system.