Synthesis and Evaluation of the Anti-Microbial Activity of New Heterocycles Containing the 1,3,4-Thiadiazole Moiety

A new series of thiadiazole-enaminones 4 were synthesized via reactions of 5-acetyl-1,3,4-thiadiazoles 3 with dimethylformamide-dimethylacetal (DMF-DMA). The simple phenyl substituted thiadiazole-enaminone 4f was used as a synthetic precursor for the preparation of a wide variety of new heterocyclic compounds, including the 5-substituted-1,3,4-thiadiazole derivatives 5, 6, 11, 12 and 13, which were obtained via reactions of 4f with nitrogen nucleophiles. Also, reactions of enaminone 4f with carbon nucleophiles afforded the respective 1,3,4-thiadiazoles 8a–d. In addition, the results of the antimicrobial activities of thiadiazole-enaminones 4 and their precursors 2 and 3 indicate that some members of this series display promising activities against all tested microorganisms.