Hydrochloric Acid → 6,7-Difluoro-1-(2-fluoroethyl)-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Participants

Reaction Steps

5 ml of a 4% w/v aqueous solution of sodium hydroxide were added to a solution of the whole (0.0005 mole) of the ethyl 6,7-difluoro-1-(2-fluoroethyl)-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylate (X, R9' =2-fluoroethyl) prepared as described in Step (C5) dissolved in 15 ml of methanol. The mixture was then allowed to stand at room temperature for 5 hours, after which it was acidified by adding concentrated hydrochloric acid to precipitate crystals. These crystals were collected by filtration to give 0.11 g of 6,7-difluoro-1-(2-fluoroethyl)-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (IIa, R9' =2-fluoroethyl) as a colorless powder.

Provenance & Evidence