\ 2Alkyl6oxo8fluoro9(4methylpiperazin1yl)6Himidazo(4,5,1ij)quinoline5carboxylic acids (2Ab～2Ae) were prepared by condensation of ethyl 6fluoro7(4methylpiperazin1yl)8amino1,4dihydro4oxo3quinolinecarboxylate (5A) with the aliphatic acids in PPA. Other target compounds 2Af～2Ah, 2Bc, 2Cc, 2Aa～2Da, 2Bi and 2Ci were prepared by the condensation of 6fluoro7nitrogencontaining heterocycle8amino1,4dihydro4oxo3quinolinecarboxylic acids (9A～9D) with the corresponding acids in PPA or with ethyl orthoformate or by the diazotisation of 9B and 9C, respectively. Only 2Ab and 2Ac showed moderate antibacterial activity in in vitro test.
