[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH2:11][CH2:12][C:13]#[N:14])[CH:6]=[CH:7][C:8]=1[O:9][CH3:10].C([O-])(=O)C.[Na+].[Br:20]Br.O>C(O)(=O)C>[Br:20][C:6]1[CH:7]=[C:8]([O:9][CH3:10])[C:3]([O:2][CH3:1])=[CH:4][C:5]=1[CH2:11][CH2:12][C:13]#[N:14]To a mixture of 21 g of 3-(3,4-dimethoxyphenyl)propanenitrile, 10.3 g of sodium acetate and 400 mL of acetic acid there are added 20 g of dibromine in 50 mL of acetic acid. The resulting reaction mixture is stirred overnight and then poured into water and extracted with benzene. The organic phase is washed with aqueous sodium thiosulphate solution and then with water, dried over sodium sulphate and concentrated under reduced pressure. The crude reaction product is purified on a silica column (eluant: benzene), and the product obtained is recrystallised from ethanol to yield 19.3 g of the expected product.
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