ZnX2 (X = Cl, Br) catalyzed efficient regioselective synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole rings and their antibacterial studies
Oxadiazoles, thiadiazoles and their derivatives are important classes of heterocyclic compounds and have created great interest in synthetic organic and medicinal chemistry due to their versatile medicinal potential. 1,3,4-oxadiazole and 1,3,4-thiadiazole rings containing compounds display a remarkable broad spectrum of biological activity such as virucidal, CNS depressant, genotoxic, anticonvulsant, insecticidal, antitubercular, anti-HIV, herbicidal, anti-inflammatory and anticancer activities. Due to the wide verities of importance, many researchers have tried to synthesize 1,3,4-oxadiazole and 1,3,4-thiadiazole rings by employing new innovative methods with easy and convenient ways. We developed a facile and a regioselective synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole derivatives from reagent-based cyclization of the corresponding hydrazinecarbodithioates. 1,3,4-thiadiazoles are formed in the presence of ZnCl2 alone, whereas 1,3,4-oxadiazoles are produced when a base such as Et3N or KOH was used along with ZnCl2. Several other Zn-salts have been attempted in the same reaction; however, other Zn +2 salts with other counter ions have no catalytic activity towards the formation of the oxadiazole and thiadiazole rings. The three new 1,3,4-oxadiazoles and two new 1,3,4-thiadiazoles were synthesized. The two new 1,3,4-oxadiazoles-2-thione, one new 1,3,4-oxadiazoles-2-methylthiol and two new 1,3,4-thiadiazoles-2-methyl were used for antibacterial study by using filter paper disk diffusion and Minimum Inhibitory Concentration (MIC) methods at first time. All oxadiazoles and thiadiazoles showed potential antibacterial activity against different human pathogenic bacterial strains. The four gram positive and three gram negative bacteria were chosen for the antibacterial study. The MIC of individual compound is found to be different for different bacteria.
Anisur Rahman MD.,
"ZnX2 (X = Cl, Br) catalyzed efficient regioselective synthesis of 1,3,4-oxadiazole and 1,3,4-thiadiazole rings and their antibacterial studies"
ETD Collection for Tennessee State University.