Electron-organic chemistry. Anodic oxidation of [2.2]metacyclophanes and transannular cation radical formation

Abstract

Anodic oxidation of [2.2] metacyclophane gave a transannular dehydrogenation product, 4,5,9,10-tetrahydropyrene, dihydropyrene, and pyrene. Cyclic voltammetry revealed a one-electron transfer mechanism involving a cation radical. Half-wave potentials and ionization potentials of alkylated [2.2] metacyclophanes were compared with those of simple arene models. For the 5,13-dialkyl derivative the half-wave potential was found to be anomalously lower than that of the model suggesting the involvement of a transannular cation radical intermediate.