Phosphoric Acid → 7-Bromo-1-benzofuran

A mixture of phosphorus pentoxide (19.3 g) and phosphoric acid (64 ml, 85%) was added carefully to a stirred solution of 2-(2-bromophenoxy)acetaldehyde dimethyl acetal (69.6 g) in chlorobenzene (450 ml) at ambient temperature under nitrogen. The mixture was then heated under reflux for 20 hours, cooled and poured into ice/water (500 ml). The aqueous layer was separated and washed with dichloromethane (2×250 ml). The combined organic extracts were washed with brine (400 ml), dried (MgSO4), and the solvent removed in vacuo. The residue was purified by flash column chromatography over silica using a 1:49 mixture of ether and petroleum ether (b.p. 60-80° C.) as the eluant, followed by distillation to give 7-bromobenzo[b]furan (30.3 g) as a clear oil, b.p. 66-68° C. at 0.93 mbar.

1. temperatureThe mixture was then heated
2. temperatureunder reflux for 20 hours
3. temperaturecooled
4. customThe aqueous layer was separated
5. washwashed with dichloromethane (2×250 ml)
6. washThe combined organic extracts were washed with brine (400 ml)
7. dry with materialdried (MgSO4)
8. customthe solvent removed in vacuo
9. customThe residue was purified by flash column chromatography over silica using
10. additiona 1:49 mixture of ether and petroleum ether (b.p. 60-80° C.) as the eluant
11. distillationfollowed by distillation

ORD record

ord-b181bd654778407d96a5d9d8e01fb1cb

Source dataset

uspto-grants-2000_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06114334