[CH3:1][C:2]1[C:6]2[CH:7]=[CH:8][CH:9]=[C:10]([Br:11])[C:5]=2[S:4][CH:3]=1.[C:12](Cl)(=[O:14])[CH3:13].[Cl-].[Al+3].[Cl-].[Cl-]>ClCCl>[C:12]([C:3]1[S:4][C:5]2[C:10]([Br:11])=[CH:9][CH:8]=[CH:7][C:6]=2[C:2]=1[CH3:1])(=[O:14])[CH3:13]7.6 g (39.46 mmol) of 3-methyl-7-bromobenzothiophene (dried beforehand under vacuum over phosphorus pentoxide) and 70 ml of dichloromethane are placed in a 250 ml three-necked flask equipped with a thermometer. The mixture is cooled to 0° C. by an ice bath, 2.89 g (36.8 mmol) of acetyl chloride are added and then the reaction mixture is stirred for 5 minutes at 0 °C. 5 g of aluminium chloride are then added in small portions, the temperature being controlled so that it does not exceed 70° C., and stirring is continued at 0° C. for 45 minutes. The reaction mixture is poured onto crushed ice and extraction is carried out with ethyl acetate (3×150 ml). The organic phases are combined, washed with a saturated sodium bicarbonate solution (200 ml) and water (200 ml), dried over magnesium sulphate and then concentrated. The residue is purified by chromatography on a silica column (elution solvent: 5% ethyl acetate in petroleum ether). 8.55 g (Yield: 95%) of 2-acetyl-3-methyl-7-bromobenzothiophene are obtained in the form of a white solid. M.p.=105-107° C.
불러오는 중…
