Carbon Dioxide → 7-BROMO-2,3-DIMETHYL-1-BENZOFURAN

Reaction equation

S(=O)(=O)(O)O.C(=O)=O.[Br:9][C:10]1[CH:21]=[CH:20][CH:19]=[CH:18][C:11]=1[O:12][CH:13]([CH3:17])[C:14](=O)[CH3:15]>CC(C)=O>[CH3:17][C:13]1[O:12][C:11]2[C:10]([Br:9])=[CH:21][CH:20]=[CH:19][C:18]=2[C:14]=1[CH3:15]

Participants

Procedure

25 ml of concentrated sulphuric acid are introduced into a 100 ml three-necked flask equipped with a thermometer and a 10 ml dropping funnel and cooling is carried out to between -15 and 0° C. with a bath of solid carbon dioxide in acetone. 3-(2-Bromophenoxy)-2-butanone (5 g, 20.6 mmol) is added dropwise and stirring is continued for 5 min. The mixture is poured onto crushed ice and then extraction is carried out with ethyl acetate (3×80 ml). The organic phases are combined, dried over magnesium sulphate and concentrated. The residue is purified by silica column chromatography (elution solvent: cyclohexane). 4.24 g (Yield: 91%) of 2,3-dimethyl-7-bromobenzofuran are obtained--M.p.: 33° C.