Reaktion #1479011

Reaktionsgleichung

EtOH

diethyl bromomalonate

butanone

Potassium carbonate

→

5-Bromo-1-benzofuran-2-carboxylic Acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe mixture was refluxed for 4 h
2. 2
   Sonstigeto attain room temperature
3. 3
   Filtrationwas filtered off
4. 4
   Sonstigethe solvent was removed in vacuo
5. 5
   SonstigeThe organic layer was dried
6. 6
   Einengenconcentrated
7. 7
   Sonstigeto give an oil
8. 8
   Temperaturrefluxed for 45 minutes
9. 9
   EinengenThe reaction mixture was concentrated
10. 10
    workup.ADDITION2M aqueous H2SO4 (350 mL) was added
11. 11
    TemperaturAfter cooling to room temperature
12. 12
    Sonstigethe product precipitated
13. 13
    Sonstigewas re-crystallised in EtOH/H2O (4:1) (yield: 6.6 g, 28%)

Vorschrift

To a solution of 5-bromosalicyaldehyde (20 g, 98.5 mmol) and diethyl bromomalonate (95%, 37 g, 148 mmol) in butanone (200 mL) potassium carbonate (27.5 g, 197 mmol) was added. The mixture was refluxed for 4 h and allowed to attain room temperature Potassium carbonate was filtered off and the solvent was removed in vacuo. The residue was participated between CH2Cl2 and 1M aqueous H2SO4. The organic layer was dried and concentrated to give an oil. The oil was treated with 10% KOA/EtOH (125 mL) and refluxed for 45 minutes. The reaction mixture was concentrated and 2M aqueous H2SO4 (350 mL) was added and the mixture was warmed to 90° C. After cooling to room temperature, the product precipitated and was re-crystallised in EtOH/H2O (4:1) (yield: 6.6 g, 28%).

Quelle