Permanent group effect on nucleofugality in aryl benzoates

We herein report on the group electrophilicity of molecular fragments present in the title compounds to describe leaving group abilities in reactions of aryl benzoates toward CN−. It is found that the presence of electron-withdrawing substituents in the permanent group enhances its electrophilicity, thereby contributing to the stabilization of the tetrahedral intermediate involved in the stepwise pathway. On the other hand electron-releasing substituents attached to the permanent group enhance the nucleofugality of the leaving groups in these systems. Substituent effects are used to rationalize the activation/deactivation patterns induced by electron-withdrawing and electron-releasing groups at the aromatic rings.