Abstract
A novel series of pyrazolyl 1,3,4-thiadiazines 5a-c,8a-c,12,15a-c,17a-c,and 20 was prepared from the reaction of pyrazole-1-carbothiohydrazide 1a,b with 2-oxo-N0-arylpropanehydrazonoyl chloride,2-chloro-2-(2-arylhydrazono)acetate,and 3-bromoacetylcoumarin.Moreover,the regioselective reaction of 5-pyrazolone-1-carbothiohydrazide 1a with 4-substituted diazonium salts and 4-(dimethylamino)benzaldehyde gave the corresponding hydrazones 21a-c and 22.The newly prepared compounds were characterized by spectroscopy and elemental analysis.Many new synthesized compounds showed considerable antimicrobial activity against tested microorganisms.Hydrazones 21a-c and 22 showed remarkable antibacterial and antifungal activities.4-(2-(p-tolyl)hydrazineylidene)-pyrazole-1-carbothiohydrazide 21a displayed the highest antibacterial and antifungal activities with minimum inhibitory concentration(MIC)values lower than standard drugs chloramphenicol and clotrimazole,in the range of 62.5-125 and 2.9-7.8 μg/mL,respectively.
NSTL
Mdpi