We report that destabilization of the carbocation intermediate of the stepwise solvolysis reaction of tertiary cumyl derivatives, XArC (Me), Y, by the addition of electron-withdrawing ring substituents, leads to a change in mechanism to concerted pericyclic elimination in which intramolecular proton transfer to the leaving group, Y= ArC02 or C1, is concerted with CY bond cleavage (see 1).
