Rearrangements of 5‐isoxazolylhydrazines: 1‐amino‐ and 4‐aminopyrazolin‐5‐ones

Abstract

Abstract 5‐Isoxazolylhydrazines rearranged to 1‐aminopyrazolin‐5‐ones on heating. Under the same conditions, 5‐(3‐methyl‐4‐phenylisoxazolyl)hydrazine also gave 3‐methyl‐4‐amino‐4‐phenylpyra‐zolin‐5‐one. The structures of aminopyrazolones were assigned on the basis of spectroscopic properties and chemical behavior.