反应详情

A mixture of commercially available 3,5-difluorophenol (3.000 g; 23.10 mmol), anh. magnesium chloride MgCl2 (6.587 g; 69.20 mmol), and NEt3 (8.04 ml; 57.70 mmol) in anh. MeCN (100 ml) was stirred at rt, under nitrogen, for 20 min. Paraformaldehyde (3.459 g; 115.00 mmol) was then added, and the resulting mixture was heated to 80° C., under nitrogen, for 1.5 h. After cooling to rt, aq. 1N HCl (80 ml) was added, and the aq. layer was extracted with AcOEt. The mixed organic layers were dried over anh. MgSO4, filtered, and concentrated to dryness under reduced pressure affording 2,4-difluoro-6-hydroxybenzaldehyde as a yellow oil. LC-MS (conditions A): tR=0.67 min.; no ionisation.

1. temperaturethe resulting mixture was heated to 80° C., under nitrogen, for 1.5 h
2. temperatureAfter cooling to rt
3. extractionthe aq. layer was extracted with AcOEt
4. dry with materialThe mixed organic layers were dried over anh. MgSO4
5. filtrationfiltered
6. concentrationconcentrated to dryness under reduced pressure