4-Fluoroaniline → 1-(4-Fluorophenyl)-6,7,8-trifluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid

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Reaction Steps

5.7 g of 4-fluoroaniline are added dropwise to a solution of 16 g of ethyl 3-ethoxy-2-(2,3,4,5-tetra-fluorobenzoyl-acrylate (5) (X1 -X4 =F) (Appln. Ser. No. 756,469, filed July 18, 1985, now U.S. Pat. No. 4,952,695) in 50 ml of ethanol, while cooling with ice and stirring. The mixture is stirred at room temperature for 1 hour, 50 ml of ice-water are added and the precipitate is filtered off cold with suction, rinsed with water and dried at 50° C. over calcium chloride in vacuo. 16.5 g of (6) (R=4-fluorophenyl, X1 -X4 =F) of melting point 93°-95° C. are obtained.

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