Hydrochloric Acid → N-(2,4-difluorophenyl)-6-fluoro-7-chloro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

60 ml of ethylene glycol monobutyl ether, 37 g of N-(2,4-difluorophenyl)-formimino ethyl ether and 50 g of ethyl 2,4-dichloro-5-fluoro-benzoylacetate were heated at 60° to 65° C. for 5 hours. Ethanol and a little solvent were stripped off under 20 mbar. The mixture was then diluted with 150 ml of ethylene glycol monobutyl ether, 12 g of magnesium oxide were added and the mixture was heated at 110° C. for 10 hours. For working up, the reaction mixture was poured into a mixture of 150 ml of water and 50 ml of 37% strength aqueous hydrochloric acid, heated at the boiling point for 5 hours and diluted with water and the precipitate was filtered off with suction and washed with water and 2-propanol to give 49.5 g of 99% pure N-(2,4-difluorophenyl)-6-fluoro-7-chloro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid. This corresponds to 70% of theory, based on the formimino ether employed.

Provenance & Evidence