Clinafloxacin from kyorin

Example 28 7-(3-Amino-1-pyrrolidinyl)-8-chloro-1-cyclopropyl-6-fluoro-l,4-dihydro-4-oxo-3-quinolinecarboxylic acid
• A mixture of 8-chloro-1-cyclopropyl-6,7-difluoro-1,4-di- hydro-4-oxo-3-quinolinecarboxylic acid (0.6 g), anhydrous acetonitrile (6 ml), 3-aminopyrrolidine (0.35 g) and DBU (0.31 g) was refluxed for an hour. Then, 3-aminopyrrolidine (0.2 g) was more added and further refluxed for 2 hours. After cooling, the resulting precipitate was collected by filtration, dissolved in water (9 ml) containing sodium hydroxide (0.12 g) and neutralized with acetic acid. The resulting precipitate was collected by filtration and washed with water and acetonitrile successively to give the title compound (0.52 g) as colorless powder, mp 237-238 °C (decompd.).
• Analysis (%) for C₁₇H₁₇ClFN₃O₃·H2O, Calcd. (Found): C, 53.20 (52.97); H, 4.99 (4.62); N, 10.95 (10.83).

Example 29 7-(3-Amino-1-pyrrolidinyl)-8-chloro-1-cyclopropyl-6-fluoro-l,4-dihydro-4-oxo-3-quinolinecarboxylic acid hydrochloride

• To a suspension of 7-(3-amino-1-pyrrolidinyl)-8-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (100 mg) in ethanol (2 ml) was added 0.2 ml of ethanol solution of hydrogen chloride (7.0 mmol HC1/ml) and then the mixture was concentrated. The resulting residue was recrystallized from methanol to give the title compound (79 mg) as light yellow prisms, mp 263-265 °C (decompd.).
• Analysis (%) for C₁₇H₁₇ClFN₃O₃.HCl, Calcd. (Found): C, 50.76 (50.50); H, 4.51 (4.44); N, 10.45 (10.38).

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J. Med. Chem., 23, 1358 (1980)

1. Rubinstein, E. (2001). “History of quinolones and their side effects.”. Chemotherapy. 47 Suppl 3: 3–8; discussion 44–8.doi:10.1159/000057838. PMID 11549783.