反应详情

17.0 g of sodium triacetoxyborohydride (80.0 mmol) was added to a solution of 15.0 g of (1,1-dimethyl-2-oxoethyl)carbamic acid t-butyl ester obtained in Reference Example 3 (80.0 mmol), 5.16 g of 2,6-difluoroaniline (40.0 mmol) and 2.09 ml of acetic acid (40.0 mmol) in methylene chloride (400 ml) under ice-cooling, and the mixture was stirred at room temperature for 19 hours. A saturated sodium bicarbonate aqueous solution was added to the reaction mixture, followed by extraction with methylene chloride. Then, the organic layer was washed with brine and dried over anhydrous sodium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (elution solvent:hexane/ethyl acetate=20/1-10/1) to obtain 3.68 g of the title compound (yield: 31%).

1. temperaturecooling
2. extractionfollowed by extraction with methylene chloride
3. washThen, the organic layer was washed with brine
4. dry with materialdried over anhydrous sodium sulfate
5. filtrationAfter filtration
6. customthe solvent was evaporated under reduced pressure
7. customthe residue was purified by silica gel column chromatography (elution solvent:hexane/ethyl acetate=20/1-10/1)