Anodic Cyclization of 1,7-Diarylheptane-1,7-diones to the Corresponding 1,2-Diaroylcyclopentanes

A range of 1,7-diarylheptane-1,7-diones were electro-oxidized in the presence of iodide ions and a base in a mixture of methanol and toluene as the reaction solvents to give the corresponding cyclized 1,2-diaroylcyclopentanes in moderate to good yields. The reactions were carried out under extremely mild reaction conditions for which the optimal amount of electrolytic current varied from 2.05-3.17 F.mol(-1) depending on the substrates. The reaction presumably proceeds through a two-electron oxidation process in which the iodide ion plays an important role as the electron carrier.