反应详情

Under a nitrogen atmosphere, 30 g the compound (2) having been dissolved in 240 mL of THF was cooled to −78° C., to which 284 mL of sec-BuLi (1 M/L) was added, followed by stirring at the same temperature for 2 hours. 48.7 g of trimethyl borate having been dissolved in 120 mL of THF was added dropwise thereto at the same temperature, followed by stirring at the same temperature for 1 hour, and the mixture was increased in temperature to room temperature and then stirred over night. Under cooling with an ice bath, 200 mL of 3N hydrochloric acid was added to the mixture. The aqueous layer was extracted with diethyl ether, which was added to the organic layer, and the organic layer was washed with a saturated saline and then dried over anhydrous magnesium sulfate. The solvent was distilled off to obtain 48.8 g of 2,3-difluoro-5-methylphenylboric acid (3), which was used in the next step without purification.

1. additionwas added
2. additionwas added dropwise
3. stirringby stirring at the same temperature for 1 hour
4. stirringstirred over night
5. temperatureUnder cooling with an ice bath
6. extractionThe aqueous layer was extracted with diethyl ether, which
7. additionwas added to the organic layer
8. washthe organic layer was washed with a saturated saline
9. dry with materialdried over anhydrous magnesium sulfate
10. distillationThe solvent was distilled off