N[C:2]1[CH:3]=[C:4]([CH:8]=[CH:9][C:10]=1[C:11]([F:14])([F:13])[F:12])[C:5]([OH:7])=[O:6].N([O-])=O.[Na+].[OH-].[Na+].[BrH:21]>O>[Br:21][C:2]1[CH:3]=[C:4]([CH:8]=[CH:9][C:10]=1[C:11]([F:14])([F:13])[F:12])[C:5]([OH:7])=[O:6]To a stirred mixture of 3-amino-4-(trifluoromethyl)benzoic acid (Matrix Scientific, 2.05 g, 10 mmol) in aqueous HBr (48% in water, 20 mL) and H2O (67 mL) at 0° C. is added NaNO2 (0.828 g) in small portions over 15 min. After stirring the solution for 30 minutes the mixture is added dropwise to a solution of CuBr (2.5 g) in aqueous HBr (48% in water, 40 mL) and H2O (100 mL). The mixture is stirred at 75° C. for 2 hours, then room temperature for 16 hours. The mixture is treated with 20% NaOH to raise the pH above 10 and then filtered through celite. The resulting solution is acidified with 6 M HCl to pH 1 and extracted with dichloromethane (3×100 mL). Organic layers are collected, dried over Na2SO4, filtered and concentrated to give 3-bromo-4-(trifluoromethyl)benzoic acid (2.30 g, 85.5% yield). LCMS m/z=269.1, 271.1 [M+H]+.
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