Hydrochloric Acid → 1-Cyclopropyl-6,7-difluoro-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid

Beteiligte Stoffe

Reaktionsschritte

10 ml of a 4% w/v aqueous solution of sodium hydroxide were added to a solution of 0.48 g (0.0015 mole) of ethyl 1-cyclopropyl-6,7-difluoro-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylate (XXXII) (prepared as described in Preparation 3) in 20 ml of methanol, and the mixture was allowed to stand at room temperature for 5 hours. The reaction mixture was then acidified by adding concentrated hydrochloric acid to precipitate a crystalline substance, which was collected by filtration to afford 0.34 g of 1-cyclopropyl-6,7-difluoro-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (IIC) as colorless powdery crystals melting at 184°-185° C.

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