Sulfuric Acid → Ethyl 6,7-difluoro-1-(2-fluoroethyl)-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylate

Participants

Reaction Steps

A mixture of the whole (0.0022 mole) of the 3,4-difluoro-N-(2-fluoroethyl)-2-methoxyaniline prepared as described in step (C3) and 0.57 g (0.0026 mole) of diethyl ethoxymethylenemalonate was heated at 140°-150° C. for 6 hours, after which it was allowed to cool to room temperature. 2 ml of acetic anhydride and 1 ml of concentrated sulfuric acid were added in that order to the mixture, and it was then allowed to stand at room temperature. The reaction mixture was then poured into ice-water to precipitate crystals, which were collected by filtration to give 0.18 g of ethyl 6,7-difluoro-1-(2-fluoroethyl)-8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylate (X, R9' =2-fluoroethyl) as colorless crystals.

Provenance & Evidence