Hydrocarbon activation with cerium(IV) ammonium nitrate: Free radical versus oxidative pathways

The reactivity of propellane C-C bonds towards cerium(IV) ammonium nitrate (CAN) was studied utilizing photochemical initiation in acetonitrile. Synth etic as well as computational (B3LYP/6-311+G** and MP2/6-31G*) data strongl y suggest that the activation of the C-C bonds in cyclopropane and cyclobut ane derivatives involves NO3 radical attack on the hydrocarbon ring and doe s not proceed through single electron transfer. The product structures are not consistent with the intermediate formation of propellane radical cation s. These propellane systems could be generated independently by oxidation w ith charged electrophiles, by anodic oxidation, and through photo-oxidation with 1,2,4,5-tetracyanobenzene; the observed chemical behavior of radical cations is clearly different.