1-(5-Bromo-2-fluorophenyl)ethanone → 4-Bromo-1-fluoro-2-isopropenyl-benzene

Participants

Reaction Steps

A suspension of methyltriphenylphosphonium bromide (58.92 g, 162 mmol) in tetrahydrofuran (400 ml) was treated with potassium tert-butylate (18.51 g, 162 mmol), and the yellow mixture was stirred at room temperature for 20 minutes. The orange reaction mixture was cooled to 0° C., and a solution of 1-(5-bromo-2-fluoro-phenyl)-ethanone (29.33 g, 135 mmol) in tetrahydrofuran (50 ml) was added within 16 minutes. The mixture was left to warm to room temperature and stirred for 1.5 hours. For the workup, the mixture was diluted with ethyl acetate (650 ml) and extracted with water (450 ml). The organic layer separated, washed with brine (220 ml), dried and evaporated at reduced pressure. After chromatography on silica gel using a gradient of hexane/ethyl acetate=100/0 to 80/20 as the eluent, the 4-bromo-1-fluoro-2-isopropenyl-benzene was obtained as a yellow oil (28.49 g, 98% of theory).

Provenance & Evidence