反应详情

Dimethylformamide (DMF) (12.7 g) is added to vigorously stirred phosphorous oxychloride (14.4 g) at 0° C. The reaction mixture is stirred at this temperature for 30 minutes, then 3,5-dihydroxyfluorobenzene (6 g) is added. The sticky red syrup is allowed to warm to room temperature and stirred for 2 hours, then left to stand for 14 hours. Water (100 mL) is added and the mixture extracted three times with ethyl acetate (100 mL). The combined organic phases are washed with brine (100 mL), dried over magnesium sulphate and evaporated. The residue is purified by flash chromatography on silica eluting with a mixture of ethyl acetate and pentane (1:2 v/v). Fractions homogeneous in the required product are combined and evaporated to give an orange solid which is triturated with ethyl acetate to give 2,4-dihydroxy-6-fluorobenzaldehyde (2 g) as a yellow solid.

1. stirringstirred for 2 hours
2. waitleft
3. waitto stand for 14 hours
4. extractionthe mixture extracted three times with ethyl acetate (100 mL)
5. washThe combined organic phases are washed with brine (100 mL)
6. dry with materialdried over magnesium sulphate
7. customevaporated
8. customThe residue is purified by flash chromatography on silica eluting with a mixture of ethyl acetate and pentane (1:2 v/v)
9. customevaporated
10. customto give an orange solid which
11. customis triturated with ethyl acetate