Abstract3‐(3′‐,4′‐Hydroxyphenyl)sydnones were prepared by dealkylation of 3‐(3′‐,4′‐alkoxyphenyl)sydnones with concentrated sulfuric acid at room temperature in a range of 59 to 86% yield.
The acidic decomposition of 4-acetylsydnonesarylhydrazones 2 results in the formation of 4-arylhydrazo-1,2-pyrazolin-5-ones 3 and 4-arylamino-1,2,3-triazoles 4, respectively. The reactions of 4-acetylsydnones 1 with arylhydrazines 5 afford compounds 3 as the only products in the absence of solvent.