Nitrile Oxides from furazans

The first examples of furazan and furoxan nitrile oxides have been reported in the early 1990s. 4-Aminofurazan-3-carbonitrile oxide (65) was generated from the hydroximoyl chloride with base and its cycloaddition reactions investigated <92KGS687>, and the 4-phenyl analogue (66) is formed via the nitrolic acid derivative by treatment of the aldoxime with dinitrogen tetroxide <93LA44i>. Furazan-3-amidoximes react in the usual way with nitriles to yield 3-(furazan-3-yl)-1,2,4-oxadiazoles <9013941 >. 

Finally, when 2,4-dimethoxy-6-methyl-l,3,5-triazine was nitrated with nitric acid alone at 20 °C, the product was 3,4-bis(3, 5 -dimethoxy-1,3,5-triazinyl)-l,2,5-oxadiazole 2-oxide (27). This product was presumably formed by the normal dimerisation of a nitrile oxide to a furazan N-oxide, the nitrile oxide in this case being 3,5-dimethoxy-l,3,5-triazinonitrile oxide (26). The latter would be formed by tautomerism and elimination of water from the mono-nitration product 3,5-dimethoxy-2-nitromethyl-l,3,5-triazine (25) before it could be further nitrated to the product formed imder mixed acid conditions (Scheme 24). 

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