Diethyl Ether → 7-Bromo-4-fluoro-2-methylbenzofuran

Reaction equation

[Br:1][C:2]1[CH:7]=[CH:6][C:5]([F:8])=[CH:4][C:3]=1[O:9][CH2:10][C:11]#C.[F-].[Cs+].[CH2:15](OCC)C>CCN(C1C=CC=CC=1)CC>[Br:1][C:2]1[C:3]2[O:9][C:10]([CH3:11])=[CH:15][C:4]=2[C:5]([F:8])=[CH:6][CH:7]=1

Participants

Procedure

A suspension of 57 g (250 mmol) of 1-bromo-4-fluoro-2-prop-2-ynyloxy-benzene and 53 g (350 mmol) of caesium fluoride in 400 ml of diethylaniline was heated at reflux in a metal bath for 4 hours. After cooling to room temperature 1500 ml of diethyl ether were added thereto and the insoluble constituents were filtered off. The diethyl ether phase was washed three times with 600 ml of 1N hydrochloric acid, dried over sodium sulfate and concentrated in a vacuum. The crude product obtained was purified by column chromatography on silica gel (hexane). 51.4 g (89%) of 7-bromo-4-fluoro-2-methylbenzofuran were obtained as a pale yellow oil.