One-pot synthesis of trifluoromethyl- and nitroso-substituted pyrazolines and pyrazoles and their tuberculostatic activity

Abstract

3-Trifluoromethyl-substituted 4-nitrosopyrazolines and 4-nitrosopyrazoles were prepared by a one-pot synthesis from trifluoromethyl-containing 1,3-diketones, sodium nitrite in acetic acid, and hydrazines (hydrazine hydrate, methylhydrazine). 3-Trifluoromethylpyrazolines can be converted to pyrazoles on heating. The use of phenylhydrazine in these reactions led to the formation of regioisomeric 4-hydroxyimino-5-(trifluoromethyl)pyrazoline. The structure of heterocycles synthesized was established using X-ray diffraction study, 1H and 19F NMR spectroscopy. The obtained products exhibited considerable tuberculostatic activity.