Highly robust cation radical salts: Aromatic oxidants from cycloannulated aromatic donors

Abstract

A cost effective and easy Friedel-Craft Cycloannulation of simple aromatic compounds with readily available and cheap 2,5- dichloro-2,5-dimethylhexane in the presence of catalytic amount of anhydrous aluminum chloride produced various cycloannulated aromatic donors(I-XIII) in excellent yields and they were characterized by NMR spectroscopy as well as X-ray crystallography. All aromatic electron donors showed consistent reversibility upon elctrochemical oxidation at various scan rates (v = 50-1000 mVs−1). CRET, Magic Blue or NO+SbCl6- was used to produce cation radical salts. The cation radicals of V and VII were isolated in crystalline form and were analyzed by X – ray crystallography. The stability, different λmax values and the wide range of redox potential values (0.88–1.85 V vs SCE) of the cation radicals of (I-XIII) provided a wide window for the oxidation of various organic compounds. The cation radicals of II was successfully applied as the oxidant to evaluate the electron removal of tetraarylmethane and hexaarylbenzene and to evaluate a conformational switching behavior of cation radical of a biaryl compound. One electron oxidation of tetramethyl biphenylene, one electron oxidation of octamethoxychrysene and the formation of a new CC bond in octamethoxytetraphenylene were observed by applying the cation radicals of donors V, VII and VIII as the oxidant respectively.