Synthesis and antibacterial activities of 1,3,4-oxadiazole derivatives containing 5-methylisoxazole moiety

5-(5-Methylisoxazol-3-yl)-4-substituted aminomethyl-2-thin-1,3,4-oxadiazoles 3a-e and 4-acetyl-2- (5-methylisoxazol-3-yl)-5-substituted-1,3,4-oxadiazoles 5a-c have been synthesized by Mannich reaction of 5-(5-methylisoxazol-3-yl)-1,3,4-oxadiazol-2-thiol 2 with amines and cyclization of hydrazones with acetic anhydride, respectively. Moreover, 2-aryl-5-(5-methylisoxazol-3-yl)-1,3,4-oxadiazoles 6a-c have been obtained by direct condensation of 5-methylisoxazol-3-acetic acid hydrazide with aromatic acid in the presence of POCl3. The compounds synthesized have been confirmed by their elemental analyses and spectral data. Their antibacterial activities have also been evaluated.