Electron-Withdrawing Effect, Resonance Effect, and Steric Effect of α-Substituents on the Solvolysis of β-Arylalkyl Triflates

Abstract

We prepared β-arylethyl triflates having electron-withdrawing substituent on α or β position in order to study the effect of electron-withdrawing substituent on solvolses mechanism and reactivity. In this paper, solvolyses of α-COMe-β-phenylethyl triflate is reported. The reactions were followed by ¹H- and ¹⁹F-NMR. Though migrated products is main, unmigrated product is also obtained by S_N2 reaction. The migrated return ester is obtained too and the acetolysis rate of β-COMe-β-phenylethyl triflate was determined by non-linear least square analysis of the time profile. The acceleration effect which canceled the deceleration effect by the electron-withdrawing was observed as well as α-cyano group. Activation energy of these reactions was calculated by ab-initio method and discussed.