[Br:1]N1C(=O)CCC1=O.[S:9]1[CH:13]=[CH:12][CH:11]=[C:10]1[C:14]1[S:15][CH:16]=[CH:17][CH:18]=1>C(O)(=O)C.C(Cl)(Cl)Cl>[Br:1][C:13]1[S:9][C:10]([C:14]2[S:15][CH:16]=[CH:17][CH:18]=2)=[CH:11][CH:12]=1N-Bromosuccinimide (NBS, 1.12 g, 6.3 mmol) was added in small portions to a stirred solution of 1.0 g (6.01 mmol) of 2,2'-bithiophene in 10 ml of glacial acetic acid and 10 ml of chloroform. After stirring for 1 h at room temperature, the mixture was poured into ice-water and extracted into chloroform (75 ml). The organic layer was washed with aqueous sodium bicarbonate solution, water, and then dried over magnesium sulfate and evaporated. The residue was subjected to flash chromatography on silica gel using hexane to give 1.3 g (88%) of a light green solid, m.p. 55°-56° C.
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