An economical 11-step synthesis of T-3761 (1), a new quinolone antibacterial agent discovered by us, has been developed. Commercially available 2,3,4,5-tetrafluorobenzoic acid (2) has been transformed to 4-(1-acetaminocydopropyl)-2,3,5-trifluorobenzoic acid (10) in 6 steps (68% yield), including cyclopropane-ring formation of the 4-cyanomethylbenzoate intermediate (6) at its side chain. Conversion of 10 to the beta-keto ester 11 and a subsequent 2-step pyridoxazine annulation procedure afforded 13 (80% yield), which, on N,O-deprotection, provided 1 (48% overall yield from 2). The overall reaction sequence can be carried out without chromatographic purification of intermediates.