Synthesis of New Fluoroquinolones Containing a N-[5-(Fluorobenzylthio)-1,3,4-thiadiazol-2-yl]piperazine moiety

Abstract

A series of N-[5-(fluorobenzylthio)-1,3,4-thiadiazol-2-yl]-piperazinylquinolones derivatives (4a-i) have been synthesized as potential antibacterial agents. The 2-amino-5-(fluorobenzylthio)-1,3,4-thiadiazole derivatives (6a-c) were obtained from 5-amino-1,3,4-thiadiazol-2-thiol (5). The treatment of compound 5 with fluorobenzyl chloride derivatives afforded S-benzyl intermediates 6a-c. Diazotization of amine 6a-c with NaNO₂ in hydrochloric acid in the presence of copper powder gave the corresponding 2-chloro-5-(fluorobenzylthio)-1,3,4-thiadiazoles (7a-c). Reaction of compounds 7a-c with piperazinyl quinolones (1-3) in DMF in the presence of NaHCO₃ gave the target compounds 4a-i. The structure of synthesized compounds was confirmed by elemental analysis, IR and ¹H NMR spectra.