199339-10-1

Reaction of 5-aryl-2-amino-1,3,4-oxadiazoles (B(I-VI)), obtained by the oxydative cyclization of aromatic aldehyde semicarbazones (A(I-VI)), with α-chloro-α-phenylacetyl chloride and a-bromopropionyl bromide yielded 5-aryl-2-[(α-chloro-α-phenylacetyl)amino]-1,3,4-oxadiazoles (Ia-VIa) and 5-aryl-2-[(α-bromopropionyl)amino]-1, 3,4-oxadiazoles (VIIa-XIIa), respectively. Furthermore, Ia-XIIa were refluxed with ammonium thiocyanate to give 5-phenyl/methyl-2-[(5-aryl-1,3,4-oxadiazol-2-yl)imino]-4-thiazolidinones (It-XIIt). All compounds were tested for antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. They were all found to possess significant activity against S. aureus with MIC values ranging from 0.24 to 125 μg/ml. LD50 of compounds chosen as prototypes are estimated.