The oxidation of N-aminoheterocyclic compounds.

The oxidation of all 1,1-disubstituted hydrazines is reviewed as a model for the oxidation of N-aminoheterocyclic compounds and the mechanism of the reactions discussed. The oxidation of N-aminotriazoles is studied with a wide range of oxidants and shown to proceed most efficiently with lead tetraacetate. The products are shown to be acetylenes or nitriles, depending on the structure of the triazole. Highly reactive medium-ring cyclic acetylenes are also produced by this method and may be trapped by tetraphenyl-cyclopentadienone. The acetylenes are also shown to be produced efficiently from 1,2-bis-hydrazones by lead tetraacetate oxidation. The oxidation of N-amino-l,2,3-benzotriazin-4-ones is studied and shown to proceed in part through benzocyclo-propenones and in part through indazolones. Both types of reactive intermediate are powerful electrophiles. The oxidation of indazolinones is shown to be a related reaction. The direction of opening of the cyclopropenone ring is markedly influenced by the electronic character of substituents in the benzene ring, leading to products of predictable structure. The relationship between benzocyclopropenone and the known cyclopropenones is discussed.