Benzofuran → 3-Bromo-1-benzofuran

Temperature

0 °C

Bromine (13.1 mL, 250 mmol) dissolved in chloroform (50 mL) is added dropwise to a solution of benzo[b]furan (25 g, 210 mmol) in chloroform (200 mL) at −10° C. over 20 minutes. The mixture is then stirred at 0° C. for 1 hour and the volatiles are evaporated. The residue is stirred with ethanol (50 mL) and then filtered. The solid material is washed with diethyl ether (100 mL) on the filter. This furnishes 23.0 g (39%) of 2,3-dibromo-2,3-dihydro-benzo[b]furan as white crystalline material. Potassium hydroxide pellets (9.3 g, 165 mmol) are dissolved in ethanol (40 mL) and cooled to 0° C. 2,3-Dibromo-2,3-dihydro-benzo[b]furan (23.0 g, 82.7 mmol) dissolved in ethanol (90 mL) is added dropwise hereto at a constant temperature of 0° C. After complete addition the mixture is heated to reflux for 2 hours. The mixture is concentrated in vacuo and water (100 mL) is added. The aqueous layer is extracted with ethyl acetate (3×100 mL). The combined organic fractions are washed with brine (100 mL), dried (MgSO4) and concentrated to furnish 14.7g (90%) of the wanted product as an oil.

1. customthe volatiles are evaporated
2. stirringThe residue is stirred with ethanol (50 mL)
3. filtrationfiltered
4. washThe solid material is washed with diethyl ether (100 mL) on the filter
5. dissolutionare dissolved in ethanol (40 mL)
6. temperaturecooled to 0° C
7. additionis added dropwise hereto at a constant temperature of 0° C
8. additionAfter complete addition the mixture
9. temperatureis heated
10. temperatureto reflux for 2 hours
11. concentrationThe mixture is concentrated in vacuo and water (100 mL)
12. additionis added
13. extractionThe aqueous layer is extracted with ethyl acetate (3×100 mL)
14. washThe combined organic fractions are washed with brine (100 mL)
15. dry with materialdried (MgSO4)
16. concentrationconcentrated

ORD record

ord-b013d651b6574729a4f272e502124691

Source dataset

uspto-grants-2009_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07534791B2