7-Bromo-1-ethyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic Acid Ethyl Ester is an intermediate in the synthesis of Rosoxacin (R693580), an antibacterial agent used against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae.