[F:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([F:8])[C:3]=1[CH:9]1[O:13][N:12]=[C:11]([C:14](=[O:16])[CH3:15])[CH2:10]1.[Br:17]Br.BrBr.ClCCl>ClCCl>[Br:17][CH2:15][C:14]([C:11]1[CH2:10][CH:9]([C:3]2[C:4]([F:8])=[CH:5][CH:6]=[CH:7][C:2]=2[F:1])[O:13][N:12]=1)=[O:16]To a 500 mL flask equipped with a mechanical stirrer, thermometer, addition funnel and scrubber was added 1-(4,5-dihydro-5-(2,6-difluorophenyl)-3-isoxazolyl)ethanone (i.e. the product of Step B) (60.0 g, 0.27 mmol) and dichloromethane (130 mL). The reaction mixture was heated at 33° C., and then bromine (39.2 mL, 0.24 mol) in dichloromethane (100 mL) was added dropwise via the addition funnel. After about 5 mL of the bromine/dichloromethane solution had been added, the addition was stopped and the reaction mixture was stirred at 33° C. for about 10 minutes, during which time the color of the reaction mixture changed from red to yellow. The reaction mixture was cooled to 5° C., and then the remaining bromine/dichloromethane solution was added dropwise over 90 minutes. After the addition was complete, the reaction mixture was washed with aqueous sodium bisulfite solution (3.5 g in 100 mL of water). The organic layer was concentrated under reduced pressure, hexanes were added, and the resulting solid precipitate was collected by filtration and washed with hexanes to provide the title compound as a brown solid (73 g), which was used without further purification.
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