1.2.3- Oxadiazolium hydroxide, anhydro-5-hydroxy

Reaction of the A-nitrosoglycine (394) with acetic anhydride gave the anhydro-5-hydroxy-l,2,3-oxadiazolium hydroxide (395). Reaction with DMAD resulted in formation of the intermediate 1 1 cycloadduct (396) which was not isolated and which lost CO2 under the thermal reaction conditions to give dimethyl l-phenylpyrazole-3,4-dicarboxylate (397) (83MI40300). This reaction is capable of considerable variation in terms of the substituents... 

Reaction of the A-nitrosoglycine (394) with acetic anhydride gives the anhydro-5-hydroxy-1,2,3-oxadiazolium hydroxide (395). 

Oxadiazol-2-ones (Anhydro-2-hydroxy-l,3,4-oxadiazolium Hydroxides) (146)... 

Table 1 Selected values from IR, UV, and 13C NMR analysis of 3-substituted-anhydro-5-hydroxy-1,2,3,4-oxadiazolium hydroxides 4 from nitrosation and cyclization of bromonitroformaldehyde A/-arylhydrazones 36 (Equation 5) <1997CHE880,...

---