[Cl:1][C:2]1[CH:7]=[C:6](I)[C:5]([F:9])=[C:4]([Cl:10])[C:3]=1[F:11].C([Mg]Cl)(C)C.[F:17][C:18]([F:25])([F:24])[C:19](OCC)=[O:20]>O1CCCC1.COC(C)(C)C>[Cl:10][C:4]1[C:5]([F:9])=[C:6]([C:19](=[O:20])[C:18]([F:25])([F:24])[F:17])[CH:7]=[C:2]([Cl:1])[C:3]=1[F:11]
1,3-Dichloro-2,4-difluoro-5-iodobenzene (4.0 g) was dissolved in tetrahydrofuran and cooled to −10 degree. A 2.0 M solution of isopropylmagnesium chloride in tetrahydrofuran (10 ml) was added dropwise via a dropping funnel. The reaction mixture was stirred for 1 hour at same temperature. A solution of ethyl trifluoroacetate (2.76 g) in tetrahydrofuran (6 ml) was added dropwise and the reaction mixture was allowed to warm to ambient temperature. The reaction mixture was diluted with t-butyl methyl ether and washed with 1 N NaOH and then brine. The combined extracts were dried over magnesium sulfate. After filtered off, the filtrate was concentrated in vacuo to give crude product which was purified with Kugel-Rohr to give 1-(3,5-dichloro-2,4-difluorophenyl)-2,2,2-trifluoroethanone (2.5 g).
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