N[C:2]1[C:10]([F:11])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].C(#N)C.[BrH:15].N([O-])=O.[Na+]>O.[Cu]Br>[Br:15][C:2]1[C:10]([F:11])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5]In a 1 L, three necked flask fitted with a dropping funnel and thermometer, were charged 2-amino-3-fluorobenzoic acid (20.0 g, 0.13 mol) and acetonitrile (160 mL). After cooling to 0° C., HBr (47%, 160 mL) was added drop wise over 10 min. To the resulting solution a solution of NaNO2 (10.0 g, 0.14 mol) in water (20.0 mL) was added drop wise over 1 h. After addition, the reaction mixture was stirred at 0° C. for 5 min, and copper(I) bromide (22.0 g, 0.15 mol) was added portionwise over 30 min. Stirring was continued at 70° C. in a an oil bath for 1 h. After cooling to 0° C., 700 mL of water was added and the precipitate was filtered, washed with cold water and dried under vacuum to give 28.23 g (100%) of the title compound as a white solid. The crude product was used in the next step without purification.
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