Reaktion #46447

Reaktionsgleichung

paraformaldehyde

3-fluorophenol

ethylmagnesium bromide

HCl

NEt3

→

4-fluoro-2-hydroxy-benzaldehyde

Ausbeute 36.3%

Lösungsmittel

THF

EtOAc

THF

benzene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewas removed by distillation at 80° C
2. 2
   workup.ADDITIONAdditional benzene (50 ml) was added to the reaction
3. 3
   TemperaturAfter heating
4. 4
   Temperaturat reflux for 3 hours
5. 5
   Temperaturto cool to room temperature
6. 6
   Sonstigethe organic layer was separated
7. 7
   Waschenwashed with H2O
8. 8
   TrocknenAfter drying over MgSO4
9. 9
   Sonstigethe solvent was removed under reduced pressure
10. 10
    SonstigeThe resulting residue was purified by flash chromatography

Vorschrift

To a solution of 3-fluorophenol (1 ml, 11 mmol) in THF (20 ml) in a three-neck flask was added ethylmagnesium bromide (5.5 ml, 5.5 mmol, 1M in THF). After stirring at room temperature for 2 hours, benzene was added to the reaction mixture and THF was removed by distillation at 80° C. Additional benzene (50 ml) was added to the reaction, followed by NEt3 (2.3 ml, 16.5 mmol) and paraformaldehyde (1 g, 33.3 mmol). After heating at reflux for 3 hours, the reaction mixture was allowed to cool to room temperature and was poured into 250 ml of 10% HCl. EtOAc was added and the organic layer was separated and washed with H2O. After drying over MgSO4, the solvent was removed under reduced pressure. The resulting residue was purified by flash chromatography to give 4-fluoro-2-hydroxy-benzaldehyde as a white solid (560 mg, 36%), 1H NMR (CDCl3, 300 MHz) δ: 6.71 (m, 2H), 7.56 (dd, 1H, J=6.3 Hz, 8.6 Hz), 9.84 (s, 1H), 11.36 (s, 1H).

Quelle