Radical Formation in the Oxidation of 2,2'-Azo-2-methyl-6-heptene by Thianthrene Cation Radical

Reaction of 2,2'-azo-2-methyl-6-heptene (1) with thianthrene cation radical perchlorate (Th(*)(+)ClO(4)(-)) in CH(2)Cl(2) solution containing 2,6-di-tert-butyl-4-methylpyridine (DTBMP) gave a mixture of nine C(8) hydrocarbons, namely, 1,1,2-trimethylcyclopentane (4, 2.2%), 6-methyl-1-heptene (5, 2.2%), 2-methyl-1,6-heptadiene (6, 9.8%), 2,2-dimethyl-1-methylenecyclopentane (7, 2.9%), 6-methyl-1,5-heptadiene (8, 39%), 3,3-dimethyl- (9, 7.6%), 4,4-dimethyl- (10, 11%), 1,2-dimethyl- (11, 5.4%), and 1,6-dimethylcyclohexene (12, 1.5%). The amounts of acyclic dienes (6, 8) fell and of cyclohexenes (9, 10) rose when DTBMP was omitted from or diminished in the solution. The results provide firm evidence (products 4, 5, and 7) for the formation of the 2-methyl-6-hepten-2-yl radical (2), although the major fate of 2 is its oxidation to the corresponding cation 13, the origin of the bulk of the other products.