1994 年 42 巻 12 号 p. 2629-2632
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-acetaminocyclopropyl)-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 β-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.
