Sodium Hydroxide → 1-Cyclopropyl-6-fluoro-7-chloro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

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Reaction Steps

To 1-cyclopropyl-6-fluoro-7-bromo-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (0.2 g) is added thionyl chloride (2 ml) and the mixture is refluxed for 1 hour. After cooling, the reaction mixture is poured into ice-water and made alkaline with 10% aqueous sodium hydroxide solution. After stirring for 30 minutes, the resultant is extracted with dichloromethane. The aqueous layer is made acidic with 10% hydrochloric acid and then extracted with dichloroethane. The solvent is concentrated and the residue is recrystallized from acetic acid to give 1-cyclopropyl-6-fluoro-7-chloro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (80 mg), as white crystals, m.p. 258°-260° C.

Provenance & Evidence