[CH3:1][C:2]1[C:3]([NH:11][C:12](=[O:17])[C:13]([F:16])([F:15])[F:14])=[C:4]([C:7]([O:9][CH3:10])=[O:8])[S:5][CH:6]=1.C(O)(=O)C.[Br:22]N1C(=O)CCC1=O.O>[Cl-].[Na+].O>[Br:22][C:6]1[S:5][C:4]([C:7]([O:9][CH3:10])=[O:8])=[C:3]([NH:11][C:12](=[O:17])[C:13]([F:16])([F:14])[F:15])[C:2]=1[CH3:1]To a stirred mixture of methyl 4-methyl-3-[(trifluoroacetyl)amino]thiophene-2-carboxylate (11.7 g, 43.8 mmol) and acetic acid (150 mL) was added 1-bromopyrrolidine-2,5-dione (15.6 g, 88.0 mmol) at room temperature. Then, this mixture was stirred at 80° C. for 6 h. After cooling to room temperature, the mixture was poured into water (600 mL) and brine (300 mL). The precipitate was collected by filtration, washed with water, dried under vacuum to afford the title compound (9.40 g, 62%) as a white solid:
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