[Cl:1][C:2]1[CH:3]=[C:4]([CH:7]=[C:8]([O:10][C:11]2[CH:16]=[C:15]([O:17]C)[CH:14]=[C:13]([F:19])[C:12]=2[Cl:20])[CH:9]=1)[C:5]#[N:6].B(Br)(Br)Br>C(Cl)Cl>[Cl:1][C:2]1[CH:3]=[C:4]([CH:7]=[C:8]([O:10][C:11]2[CH:16]=[C:15]([OH:17])[CH:14]=[C:13]([F:19])[C:12]=2[Cl:20])[CH:9]=1)[C:5]#[N:6]Under nitrogen atmosphere, 3-chloro-5-(2-chloro-3-fluoro-5-methoxyphenoxy)-benzonitrile (50-4) (9.6 g, 30.8 mmol) was diluted in CH2Cl2 (60 mL, 0.5M) and then cooled to 0° C. To this solution BBr3 (61.5 mL, 61.5 mmol, 1M in CH2Cl2) was slowly added to the reaction. The reaction mixture was allowed to slowly warm to room temperature and stir for 12 hours. It was then cooled to 0° C. and slowly quenched with water (60 mL). The aqueous layer was then extracted with methylene chloride (3×30 mL). The organic extracts were dried over sodium sulfate and concentrated. Silica gel chromatography (1%-20% EtOAc/Hexanes) gave 3-chloro-5-(2-chloro-3-fluoro-5-hydroxyphenoxy)benzonitrile (50-5) (3.2 g, 35%). LCMS (ES) m/z 298.2 (M)+.
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