Water → Ethyl 7-fluoro-1-[2-(S)-fluoro-1-(R)-cyclopropyl]-1,4-dihydro-8-methoxy-5-nitro-4-oxoquinoline-3-carboxylate

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Reaction Conditions

Reaction Steps

Isoamyl nitrite (3.81 g, 32.5 mmol) was added to dimethylformamide (60 ml), and while stirring at 70° C., a solution, wherein ethyl 6-amino-7-fluoro-1-[2-(S)-fluoro-1-(R)-cyclopropyl]-1,4-dihydro-8-methoxy-5-nitro-4-oxoquinoline-3-carboxylate (8.90 g, 23.2 mmol) was dissolved in dimethylformamide (120 ml), was added dropwise thereto over a period of 3 hours. After completion of dripping, the reaction solution was stirred at 70° C. for 1 hour, allowed to cool, and then poured into water (500 ml). After extraction with ethyl acetate (300 ml×3), the organic layers combined were washed with 1 mol/l hydrochloric acid (300 ml) and saturated saline solution (200 ml×2) in that order, and then dried over anhydrous sodium sulfate. After filtering, the filtrate was concentrated under a reduced pressure, and the crude crystals obtained were recrystallized in ethanol and then dried under a reduced pressure. 3.81 g (45%) of the title compound was thereby obtained in the form of yellow crystals.

Provenance & Evidence