反应详情

Methyl cyanoacetate (51.1 g) is added dropwise to a suspension of sodium hydride (43.3 g, in oil, 55-65 w/w %) in dry tetrahydrofuran (600 ml) while maintaining the internal temperature between 15° C. and 20° C. on an ice bath. To the reaction mixture is added dropwise the crude 2,3,4,5-tetrafluorobenzoyl chloride (110.5 g) as obtained above, and the mixture is stirred while maintaining the internal temprature as above. After 30 minutes, methylene chloride is added to the reaction mixture and the reaction product is extracted with 3% aqueous sodium bicarbonate. The extract is then washed with methylene chloride to remove the remaining methyl cyanoacetate. The extract is acidified with conc. HCl and the resulting precipitate is filtered and washed with dil. HCl to afford methyl 2-cyano-3-hydroxy-3-(2,3,4,5-tetrafluorophenyl)acrylate (122.2 g) as pale yellow crystals, m.p. 71°-73° C.

1. temperaturewhile maintaining the internal temperature between 15° C. and 20° C. on an ice bath
2. customas obtained above, and the mixture
3. temperaturewhile maintaining the internal temprature as above
4. extractionthe reaction product is extracted with 3% aqueous sodium bicarbonate
5. washThe extract is then washed with methylene chloride
6. customto remove the remaining methyl cyanoacetate
7. filtrationthe resulting precipitate is filtered
8. washwashed with dil. HCl