2-Amino-4-(t-butylamino)-5-fluoropyrimidine → Ethyl 1-[4-(t-butylamino)-5-fluoropyrimidin-2-yl]-8-chloro-6,7-difluoro-4-oxo-1,4-dihydroquinoline-3-carboxylate

To 3 ml of chloroform solution of ethyl 3-ethoxy-2-(3-chloro-2,4,5-trifluorobenzoyl)acrylate prepared from 210 mg of ethyl 3-chloro-2,4,5-trifluorobenzbylacetate by normal process was added 340 mg of 2-amino-4-(t-butylamino)-5-fluoropyrimidine. The solution was concentrated under reduced pressure. To the residue were added 550 mg of anhydrous potassium carbonate and 2 ml of N,N-dimethylformamide, and the mixture was stirred at 90° C. for 1 hour and 10 minutes and allowed to cool. The solution was separated by adding 30 ml of chloroform and 300 ml of distilled water, and the chloroform layer was washed twice with 300 ml of distilled water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was separated by column chromatography (silica gel, 16 g; eluent: chloroform:methanol, 200:1), and the corresponding fractions were collected and concentrated under reduced pressure. To the residue was added 0.5 ml of ethanol, and the precipitate was collected by filtration and washed with ethanol and diisopropylether successively to obtain 98 mg of the title compound as a colorless powder.