Abstract: Cyclopentane-1, 3-diyl radical cations were generated from the 1-methyl-and 1, 4- dimethyl substituted bicycle [2.1. O] pentanes lb, c through photoinduced electron transfer (PET) and radiolytic oxidation. The unsymmetrical bridgehead-substituted bicyclopentane lb rearranged spontaneously and exclusively to the 3-methylcyclopentene 3b under PET conditions. ESR studies showed similarly that 3b'+ was the only final oxidation product of ...