Spontaneous oxidation of organic donors to their cation radicals using Bronsted acids. Identification of the elusive oxidant

Various electron-rich aromatic and olefinic donors (D) are readily converte d to their cation radicals (D+.) in the presence of strong protic acids, ev en in nonpolar solvents such as dichloromethane. By using the three prototy pical organic donors octamethylbiphenylene (OMB), adamantylideneadamantane (AA) and the isomeric fused homoadamantene (FHA), we identify the protonate d donor (D-H+) as the effective oxidant for electron transfer from the orga nic donor (i.e., D-H++D --> D-H-.+D+.). The subsequent reduction of (D-H-.) to the dihydro product D-H-2 is demonstrated by the isolation of 2,2'-biad amantane, the structure of which is established by X-ray crystallography.