Reaktion #682203

Reaktionsgleichung

4-amino-3-bromo-2,5-difluorobenzaldehyde

sodium nitrite

ethyl acetate

→

3-bromo-2,5-difluorobenzaldehyde

Ausbeute 44.1%

Lösungsmittel

acetic acid

hypophosphoric acid

water

—

petroleum ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturcooling
2. 2
   Extraktionthe aqueous phase extracted with DCM
3. 3
   TrocknenThe combined organic phases were dried over sodium sulfate
4. 4
   Sonstigeevaporated

Vorschrift

4-amino-3-bromo-2,5-difluorobenzaldehyde (3.4 g, 14.3 mmol) was dissolved in acetic acid (18 mL) before addition of hypophosphoric acid (50% in water, 39 mL). A solution of sodium nitrite (1.4 eq, 1.4 g) in water (8 mL) was then added dropwise under ice-cooling. After stirring at rt for 2 h, the reaction mixture was poured onto a mixture ice/water and the aqueous phase extracted with DCM. The combined organic phases were dried over sodium sulfate and evaporated. A column chromatography (0 to 10% ethyl acetate in petroleum ether) afforded 3-bromo-2,5-difluorobenzaldehyde (1.3 g, 6.3 mmol, 44%). 1H NMR (d6-DMSO) δ 10.15-10.12 (m, 1H), 8.13 (ddd, J=8.0, 5.0, 3.0 Hz, 1H), 7.66 (ddd, J=8.0, 5.0, 3.0 Hz, 1H).

Quelle