Hydrochloric Acid → 7-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]-8-methoxy-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid

Participants

Reaction Steps

After dissolving ethyl 7-fluoro-1-[2-(S)-fluoro-1-(R)-cyclopropyl]-1,4-dihydro-8-methoxy-4-oxoquinoline-3-carboxylate (34.0 g, 105 mmol) in acetic acid (400 ml) and then adding concentrated hydrochloric acid (400 ml) thereto, it was heated under reflux for 3 hours. After cooling, the reaction solution was poured into ice water (1500 ml), and the precipitated crystals were filtered out. After washing the filtered-out crystals with an excess amount of water, it was washed with cold ethanol and diethyl ether in that order, and after drying under a reduced pressure, the crude crystals obtained were purified by recrystallization from a mixed solvent of acetonitrile-ethanol and then dried under a reduced pressure. 27.1 g (87.4%) of the title compound was there by obtained in the form of a white powder.

Provenance & Evidence