Manganese diazene complexes

There are few data on the oxidation of noncondensed A-aminoazoles. Manganese dioxide converts 1,2-diamino-4-arylimidazoles into complex mixtures of the corresponding 3-amino-1,2,4-triazines (320), 2-aminoimid-azoles (321), 1,2,3-triazoles (322), and some open-chain compounds (76TL903 78JOC2693). The yield of 1,2,4-triazines 320 is usually less than 25%, but on oxidation of l,2-diamino-4,5-diphenylimidazole, it increases to 62%. It is assumed that triazines 320 are formed via a nitrene mechanism, whereas for 1,2,3-triazoles 322, the diazene mechanism is postulated. However, the latter may also apply to compounds 320. 

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