The present investigation is synthesis of some novel 1,2,4-triazolo[1,3,4]thiadiazoles derivatives with an aim of discovering potent antimicrobial agents that can be helpful in overcoming antibiotic resistance. A new series of 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles containing substituted phenylquinoline moiety (4a-4t) were synthesized in multiple steps. These derivatives were obtained in good yield by condensation of (R)-4-amino-5-sulfanyl-4,5- dihydro-1,2,4-triazol-4-phenylquinolin-2-one (3a-3t) with aromatic carboxylic acid(benzoic acid) in the presence of phosphorus oxychloride. Then structures of synthesized compounds (4a-4t) were established by their spectral analysis. These newly synthesized compounds (4a-4t) were screened for their invitro antimicrobial activity using Broth Micro Dilution technique. Bacterial strains of Escherichia coli (ATCC 8739), Pseudomonas aeruginosa(MCCB 0035), Staphylococcus aureus (ATCC 29213), and the fungal strains of Aspergillusfumigatus(NCIM 2081),Aspergillusniger(NCIM 2191), Candida albicans(NCIM 2087) were used.Compound 4t showed more potent activity against gram negative bacterial strain Escherichia coli than the standard drug Ampicillin anhydride and compound 4f, 4i, 4swere found to be more potent against fungal strain Aspergillusfumigatuswhen compared with standard drug Fluconazole.
