Abstract
It is known that the phenonium ion intermediate is formed in the solvolysis of β-arylethyl triflate. The aryl assisted acetolysis rate of α-CN,α-CF3-OTf solvolysis with two electron-withdrawing groups was equivalent to that of α-CF3-OTf. It is considered that these are two acceleration effects, that is, stabilization of cationic transition state by the electron releasing resonance of -CN and, unstabilization of the ground state by the geminal interaction between its groups and leaving group. In the present study, α,α-diCF3-OTf without the inverse electron releasing resonance in the reaction center was synthesize and the solvolyses were examined. In the acetolysis of some substituted α,α-diCF3-OTf, aryl-migrated β,β-diCF3-OAc and aryl-unmigrated E2 product were formed. The acetolysis rate of α,α-diCF3-OTf was faster than predictive value by the additivity. It is considered that the causes are unstabilization of the substrate by geminal interaction and steric unstabilization of the substrate. Substituent effect analysis and molecular orbital calculation of the stability are reported.
