Facile Synthesis and Sulfonylation of 4-Aminopyrazoles

Abstract This paper describes the synthesis of alkyl- and naphthyl-substituted 4-aminopyrazoles by mild reduction of nitrosopyrazoles. Several amines are available in nearly quantitative yield. Sulfonamide derivatives were obtained based on 4-aminopyrazoles. The structure of 15 synthesized previously unknown compounds was proved by NMR, IR spectroscopy, elemental analysis, and mass spectrometry. Quantum-chemical calculations made it possible to establish the spatial structure of their most stable conformers.