反应详情

To a mixture of magnesium turnings (440 mg, 0.01 mol, 1.2 eq) in dry tetrahydrofuran (5 mL), was added 4-bromo-1,2(methylendioxy)benzene (3.1 g, 0.01 mol, 1.1 eq) in dry tetrahydrofuran (10 mL) and bromine (0.5 mL). The resulting solution was refluxed for 2 hours. Then the mixture was cooled at room temperature and a solution of 3-bromoacetophenone (3.0 g, 0.01 mol, 1 eq) in dry tetrahydrofuran (10 mL) was added dropwise and refluxed. After 3 hours the reaction mixture was examined by LC-MS which showed complete conversion to the desired product. The mixture was quenched with 1 M HCl solution (20 mL). The aqueous phase was extracted with ethyl acetate. (3×20 mL), dried (sodium sulfate) and the solvent removed in vacuo. The crude was dissolved in toluene (30 mL) and a catalytic amount of p-toluenesulfonic acid was added. The mixture was heated to reflux for 3 h (using a Dean-Stark water trap). The solvent was removed and the residue was purified by column chromatography (cyclohexane) to afford the title compound as a colorless oil (3.7 g, 80%);

1. temperatureThe resulting solution was refluxed for 2 hours
2. temperaturerefluxed