Synthesis of mycostatics based on 4-aryldiazenyl-3,5-dimethylpyrazoles

The condensation of 3-arylhydrazinylidenepentane-2,4-diones with hydrazine hydrate, 2-hydroxyethylhydrazine, benzylhydrazine hydrochloride, and 4-hydrazinylbenzenesulfonamide hydrochloride gave 4-aryldiazenyl-3,5-dimethylpyrazoles. An alternative route to the synthesis of N-substituted 4-aryldiazenylpyrazoles is based on the alkylation of NH-pyrazoles with haloalkanes. The synthesized compounds were tested for antimicrobial activity against eight pathogenic dermatophytes, yeast-like fungi of the Candida genus and the bacteria Neisseria gonorrhoeae. The structure—activity relationship analysis showed that 4-tolyldiazenylpyrazoles bearing H, AcO(CH2)4, or HO(CH2)4 substituents at the N(1) atom have the highest mycostatic activity against all the dermatophyte strains under study. However, 4-aryldiazenyl-3,5-dimethylpyrazoles proved to be quite cytotoxic against the McCoy B cell line.