4-chloroaniline reacts with 1-(4-hydroxyphenyl)-ethanone in presence of 1-napthonicacid and copper metal as a catalyst gives 1-(4-(4-aminophenoxy) phenyl)ethanone, which on further condensation with 4-nitrotoluene-2-sulfonyl chloride gives N-(4-(4-acetylphenoxy)phenyl)-2- methyl-5-nitrobenzenesulphonamide. This derivative react wit various substituted aldehydes to give corresponding substituted chalcone derivatives (N-1). Now these derivative (N-1) on condensation with 2-aminobenzenethiol gives 2-methyl-5-nitro-N-(4-(3-(2-phenyl-2,3- dihydrobenzo[b][1,4] thiazepin-4-yl)phenoxy)phenyl)benzenesulfonamide (N-2). Structure elucidation of synthesized compounds has been made on the basis of the elemental analysis, 1H NMR spectral studies. The antimicrobial activity of the synthesized compound has been studied against the species Bacillus subtillis, Staphylococcus aureus, Escherichia coli and Salmonella typhi.