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0 °C

A solution of 0.68 g of propiolic acid in 5 ml of methylene chloride is added dropwise at 0° C. while stirring during 5 minutes to a solution of 2.18 g of N,N'-dicyclohexylcarbodiimide in 10 ml of methylene chloride and the mixture is stirred at 0° C. for 15 minutes. solution of 1.5 g of 3-(4-chloro-2-fluoro-5-hydroxyphenyl)-1-methyl-6 -trifluoromethyl-2,4(1H,3H)-pyrimidinedione in 10 ml of methylene chloride is added dropwise while stirring during 20 minutes and the mixture is stirred at 0° C. for 2 hours. Insoluble constituents are filtered off under suction and the filtrate is evaporated to dryness under reduced pressure. The residue is purified by chromatography on a silica gel column using ethyl acetate/n-hexane (1:7) as the eluent. There is obtained 2-chloro-5-[3,6-dihydro-2,6-dioxo-3-methyl -4-trifluoromethyl-1(2H)-pyrimidinyl]-4-fluorophenyl propiolate. 1H-NMR (CDCl3. 400 MHz: 7.40 ppm (d,1H), 7.21 ppm 1(d,1H), 6.36 ppm (s,1H), 3.56 ppm (d,3H). 3.15 ppm (s,1H),

1. stirringwhile stirring during 20 minutes
2. stirringthe mixture is stirred at 0° C. for 2 hours
3. filtrationInsoluble constituents are filtered off under suction
4. customthe filtrate is evaporated to dryness under reduced pressure
5. customThe residue is purified by chromatography on a silica gel column