反应详情

A three-necked round bottom flask (500 mL) equipped with dry ice condenser (−78° C., acetone/dry ice) was charged with a solution of 6-bromo-2,4-dimethyl-3-hydroxypyridine (7.2 g, 35.6 mmol) in i-propanol (100 mL) and aqueous sodium hydroxide solution (20%, 100 mL) was added. The reaction mixture was stirred vigorously at 40° C. for 5 hours while chlorodifluoromethane was bubbled continuously into the solution at a moderate rate. The reaction mixture was then cooled to room temperature and extracted with Et2O (3×100 mL). The combined extracts were washed with water (2×50 mL), dried over magnesium sulfate and concentrated in vacuo. Purification of the crude mixture by flash column chromatography using 5% ethyl acetate in hexane afforded the title compound (5.4 g, 60%).

1. additionwas added
2. customwas bubbled continuously into the solution at a moderate rate
3. extractionextracted with Et2O (3×100 mL)
4. washThe combined extracts were washed with water (2×50 mL)
5. dry with materialdried over magnesium sulfate
6. concentrationconcentrated in vacuo
7. customPurification of the crude mixture by flash column chromatography