Common radical cation intermediates in cage hydrocarbon activations

The oxidation of 3,6-dehydrohomoadamantane (1) was achieved under chemical (NO+BF4-/EtOAc, NO+OAc-/Ac2O, and NO+BF4-/CH3CN), photochemical (photoexcit ed 1,2,4,5-tetracyanobenzene), and electrochemical (Pt anode, CH3CN, NH4BF4 ) conditions. Supporting ab initio [density functional theory (BLYP) and Mo ller-Plesset perturbation theory (MP2)] computations utilizing standard bas is sets, 6-31G* (optimizations) and 6-311+G* (single-point energy evaluatio ns), agree with the experimental results implicating the involvement of the same radical cation intermediates in the activation processes. Isomeric ra dical cations formed from different precursors can equilibrate with low bar riers (2.0-11.7 kcal mol(-1)) and lead to common products. The computed and experimental adiabatic ionization potential of adamantane shows that activ ation with NO+BF4- is also likely to occur through the adamantyl radical ca tion. Hence, the bonds need not be attacked directly by the electrophile in the C-H or C-C activation of alkanes with relatively low ionization potent ials.