The synthesis of novel five- and seven-membered heterocycles was conducted using Mefenamic acid as the starting material. Involved treatment of Mefenamic acid with thiosemicarbazide yielded 5-(2-((2,3-dimethyl-phenyl)amino)phenyl)1,3,4-thiadiazol-2-amine [1], and subsequent condensation of this product with 4-N, N-dimethyl amino benzaldehyde, 4-nitro benzaldehyde, 4-bromobenzaldehyde, 4-chlorobenzaldehyde, 4-methoxybenzaldehyde, and 4-hydroxy benzaldehyde gave rise to Schiff bases [2-7]. Other studies involved the treatment of Schiff bases [2-7], with different anhydrides (succinic, maleic, phthalic, and naphthalic) to yield 1,3-oxazepine-4,7-dione rings [8-31]. Focus on the research of the antibacterial properties of some of the synthesized compounds. The well diffusion method was used to determine the in vitro anti-bacterial activity of the Staphylococcus aurius (G+), Baceillus subtilis (G+), Klebsiella pneum0niae (G-), and E. coli (G-) bacterial isolates. Some of these compounds demonstrated activity, having been characterized by studies, ¹H NMR, ¹³C NMR, and infrared spectroscopy. Their microbiological activity, however, was not inconspicuous. Indeed, during the antimicrobial activity screening, some of these compounds were found to possess good activity against bacteria (9, 19, 23, 25, and 29).