[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.[C:23](Cl)(=[O:25])[CH3:24]>C1C=CC=CC=1.[Ti](Cl)(Cl)(Cl)Cl>[C: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]=1)(=[O:25])[CH3:24]Titanium (IV) chloride (2.7 ml) was added dropwise to a stirred solution of 2-(4-fluorophenyl)-3-[4-(methylsulfonyl)phenyl]thiophene (5 g) and acetyl chloride (2.2 ml) in benzene (50 ml) at 5° to 10° C. The mixture was stirred at ambient temperature for 4 hours, poured into ice-water, and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium bicarbonate, dried and concentrated. The residue was recrystallized from a mixture of ethanol and ethyl acetate to give pale brown crystals of 5-acetyl-2-(4-fluorophenyl)-3-[4-(methylsulfonyl)phenyl]thiophene (3.7 g).
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