Trifluoromethyl-containing pyrazolinyl (p-tolyl) sulfones: The synthesis and structure of promising antimicrobial agents

The regiospecific synthesis of a novel series of nine 4-phenyl- and 3-alkyl(aryl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-tosylpyrazoles (pyrazolinyl p-tolyl sulfones), as well as their antimicrobial activity against yeast, such as fungi, bacteria, and alga are reported. The 1-p-tosyl-2-pyrazolines were obtained from the cyclocondensation reaction of 3-phenyl- and 4-alkyl(aryl)-1,1,1-trifluoro-4-alkoxy-3-alken-2-ones, [where alkyl = H, Me and aryl are -C₆H₅, 4-CH₃C₆H₄, 4-OCH₃C₆H₄, 4-FC₆H₄, 4-ClC₆H₄, 4-BrC₆H₄,] with p-tosylhydrazine in a yield of 58-92% when toluene was employed as solvent. The best activity was obtained when the structure possessed a 4-fluorophenyl substituent linked at the carbon-3 of the pyrazoline ring. Subsequently, the dehydration reaction of 3-(4-fluorophenyl) substituted 2-pyrazoline with thionyl chloride/pyridine in benzene as solvent furnished the corresponding 1H-pyrazole in only a moderate yield (49%).