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The intramolecular cyclization of a number of methoxy-substituted bibenzyls and bis(3-methoxyphenyl)methane was shown to take place upon anodic oxidation in acetonitrile or in media containing trifluoroacetic acid (TFA). Yields are low in the former solvent due to the fact that the cyclized products are more easily oxidized than their precursors and the oxidation products are not stable. In the presence of TFA, the cation radicals derived from the oxidation of the cyclized products are stable and, thus, after reduction the dihydrophenanthrenes or fluorene may be isolated in high yield. Potential step cyclic voltammetry was used to provide evidence that the reactions occur by oxidation to the dication diradicals which couple and eliminate protons. In acetonitrile, voltammetry was used to show that the coupling reaction is markedly sensitive to the conditions and appears to be catalyzed by H30+, in the absence of which no coupling was observed.

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