[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[S:9][CH:10]=[CH:11][C:12]=2[C:13]2[CH:18]=[CH:17][C:16]([S:19]([CH3:22])(=[O:21])=[O:20])=[CH:15][CH:14]=2)=[CH:4][CH:3]=1.[Br:23]Br>C(Cl)Cl.C(O)(=O)C>[Br:23][C:10]1[S:9][C:8]([C:5]2[CH:4]=[CH:3][C:2]([F:1])=[CH:7][CH:6]=2)=[C:12]([C:13]2[CH:18]=[CH:17][C:16]([S:19]([CH3:22])(=[O:21])=[O:20])=[CH:15][CH:14]=2)[CH:11]=1A solution of the crude 2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl)thiophene of Example 2a (12.6 g, up to 30 mmole) in methylene chloride (100 ml) was diluted with 75 ml of acetic acid and cooled to about 5°. A 1M solution of bromine in acetic acid (33 ml, 1.1 equiv) was added and the reaction stirred at about 5°. After 1 hour, additional bromine solution (5 ml) was added. After 2 hours total reaction time, the reaction mixture was concentrated in vacuo. The residue was dissolved in ethyl acetate and the solution washed with saturated aqueous sodium bicarbonate and brine, dried, and concentrated in vacuo. Recrystallization from ethanol gave the title compound (7.9 g), m.p. 122°-124°. Infrared and NMR spectral data were consistent with the assigned structure.
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