Synthesis of 6,8-dichloroquinolones utilizing new method and evaluation of their antibacterial activities

Several 6,8-dichloroquinolone analogues were synthesized from the key intermediate compound of 2,3,4,5-tetrachlorobenzene carbonyl chloride, which was obtained from the starting material of tetrachlorophthalic anhydride. Their in vitro antibacterial activities were evaluated. As a result of this study, compounds 21c and 21d were twofold more potent than ciprofloxacin (CPFX) and norfloxacin (NFLX) against Staphylococcus aureus-9, and with the same potent as CPFX and NFLX while against Escherichia coli-2, but were less potent than references in against Pseudomonas aeruginosa-17.