Reaction #1388

Reaction equation

ethyl 7-(1-piperazinyl)-1-cyclopropyl-6-fluoro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylate

sodium hydroxide

ethanol

→

7-(1-piperazinyl)-1-cyclopropyl-6-fluoro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Yield 56.4%

Solvents

water

Conditions

Workup

1. 1
   Temperaturethe mixture is refluxed for 1 hour
2. 2
   TemperatureAfter cooling
3. 3
   Washwashed with dichloromethane
4. 4
   ExtractionThe resultant is extracted with dichloromethane
5. 5
   Otherthe extract is dried
6. 6
   workup.DISTILLATIONThe solvent is distilled off under reduced pressure and to the residue
7. 7
   workup.ADDITIONis added ethanol
8. 8
   FiltrationThe precipitated crystals are filtered
9. 9
   Otherrecrystallized from dimethylformamide

Procedure

To ethyl 7-(1-piperazinyl)-1-cyclopropyl-6-fluoro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylate (23 mg) are added 10% aqueous solution of sodium hydroxide (3 ml) and ethanol (3 ml), and the mixture is refluxed for 1 hour. After cooling, the reaction mixture is diluted with water and washed with dichloromethane. After the aqueous layer is made acidic with acetic acid and then made weak alkaline with an aqueous sodium hydrogen carbonate. The resultant is extracted with dichloromethane and the extract is dried. The solvent is distilled off under reduced pressure and to the residue is added ethanol. The precipitated crystals are filtered and recrystallized from dimethylformamide to give 7-(1-piperazinyl)-1-cyclopropyl-6-fluoro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (12 mg), as white powder, m.p. 231°-233° C.

Source