Quinolone antibacterial agents continue to show promise of being an important class of therapeutically useful compounds.'Most of these agents, which have broad spectrum activity, are substituted at the 7-position by cyclic aliphatic amines (side chains), especially diamines such as piperazine. Notable examples are norfloxacin (la), ciprofloxacin (lb), enoxacin (IC), and ofloxacin (ld).