M. Yu. Malov

Synthesis and structure of 5-hydrazino- and 5-hydroxyamino-3-aryl-2-pyrazolines and-2-isoxazolines

It was established by the methods of 1H and 13C NMR spectroscopy that the oximohydrazones and bis(hydrazones) of aroylacetic aldehydes exist in the form of the corresponding 5-hydrazino- and 5-hydroxyamino-3-aryl-2-pyrazolines and -2-isoxazolines. The features of the aromatization of these compounds to the corresponding pyrazoles and isoxazoles were studied. Data on the mass-spectral study of the 5-hydroxyamino-2-pyrazoline-5-hydrazino-2-isoxazoline tautomerism in the gas phase are presented.

5-Hydrazino-2-pyrazolines

Abstract1-Acyl-5-hydrazino-2-pyrazolines have been obtained by reaction of the appropriate hydrazines with aliphatic 1,3-diketones, 1-acyl-5-hydroxy-2-pyrazolines, and 1-acyl-5-methylene-2-pyrazolines. The latter were synthesized by acylating 3,4,4,5-tetramethyl-4H-pyrazole with carboxylic anhydrides. The structures of the products were established by 1H and 13C NMR spectroscopy and mass spectrometry.

Structure of asymmetric 5-hydrazino-2-pyrazolines

NMR (1H and 13C) spectroscopy was used to show the existence of ring-ring tautomers for 5-hydrazino-2-pyrazolines with asymmetric structure and the predominant formation of cis-isomers for 4-substituted compounds.