Microwave-Assisted Synthesis of Some 1,3,4-Oxadiazole Derivatives and Evaluation of Their Antibacterial and Antifungal Activity

A series of substituted 1,3,4-oxadiazole derivatives (3a–f) and (6a–f) have been synthesized from diphenylacetic acid hydrazide under microwave irradiation in various reaction conditions. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, and 1H NMR. These targeted compounds have been tested for their antibacterial and antifungal activities compared to ampicillin and griseofulvin as standard drug. Compounds 3a, 3e, 3f, 6c, 6d, 6e, and 6d exhibited the maximum antibacterial activities while 3b, 3c, 3d, 3e, 6a, 6d, and 6e exhibited the maximum antifungal activities. 1. Introduction Oxadiazole has occupied a unique place in the field of medicinal and pesticide chemistry due to its wide range of activities. Bhandari et al. [1] have reported the design, synthesis, and evaluation of anti-inflammatory, analgesic, and ulcerogenicity of novel S-substituted phenacyl-1,3,4-oxadiazole-2-thiol and Schiff bases of diclofenac acid as nonulcerogenic derivatives whereas Narayana et al. [2] have synthesized some new 2-(6-methoxy-2-naphthyl)-5-aryl-1,3,4-oxadiazoles as possible nonsteroidal anti-inflammatory and analgesic agents. Synthesis and evaluation of anti-inflammatory, analgesic, ulcerogenic, and lipid peroxidation properties of ibuprofen derivatives have been studied by Amir and Kumar [3] while Hui et al. [4] have carried out the synthesis and antibacterial activities of 1,3,4-oxadiazole derivatives containing 5-methylisoxazole moiety. 1,3,4-Oxadiazole derivatives have been synthesized by ？ahin et al. [5] and they have also studied their antifungal activity. Novel chiral and achiral benzenesulfonamides bearing 1,3,4-oxadiazole moieties have been synthesized by Zareef et al. [6] and studied for their antimalarial activity. Husain and Ajmal [7] have synthesized novel 1,3,4-oxadiazole derivatives and investigated their anticonvulsant properties. Burbuliene et al. [8] have reported the synthesis and anti-inflammatory activity of derivatives of 5-[(2-disubstituted amino-6-methylpyrimidin-4-yl)-sulfanylmethyl]-3H-1,3,4-oxadiazole-2-thiones while Padmaja et al. [9] have studied the synthesis and antioxidant activity of disubstituted 1,3,4-oxadiazole, 1,3,4-thiadiazoles, and 1,2,4-triazoles. El-Emam et al. [10] have synthesized certain 5-(1-adamantyl)-2-substitutedthio-1-3-4-oxadiazoles and 5-(1-adamantyl)-3-substituted aminomethyl-1,3,4-oxadiazoline-2-thiones and studied their anti-HIV-1 activity whereas synthesis and antitumor activity of some new 1,3,4-oxadiazole, pyrazole, and pyrazolo[3,4-d]pyrimidine derivatives