[Br:1][C:2]1[C:7]([O:8][CH3:9])=[CH:6][C:5]([C:10](=[O:13])[CH2:11][CH3:12])=[CH:4][C:3]=1[O:14][CH3:15].[Br-:16].[Br-].[Br-].[NH+]1C=CC=CC=1.[NH+]1C=CC=CC=1.[NH+]1C=CC=CC=1.C([O-])(O)=O.[Na+]>C1COCC1>[Br:16][CH:11]([CH3:12])[C:10]([C:5]1[CH:6]=[C:7]([O:8][CH3:9])[C:2]([Br:1])=[C:3]([O:14][CH3:15])[CH:4]=1)=[O:13]To a solution of 1-(4-bromo-3,5-dimethoxyphenyl)propan-1-one (1.50 g, 5.49 mmol) in anhydrous THF (20 mL) was added pyridinium tribromide (1.93 g, 6.04 mmole). The reaction was stirred at room temperature for 2 hrs then neutralized with a solution of saturated aqueous NaHCO3. The mixture was extracted with EtOAc the combined organics were washed with saturated aqueous NaHCO3 and brine then dried over Na2SO4 and concentrated in vacuo. Purification by chromatography (10-20% EtOAc-hexanes) gave 2-bromo-1-(4-bromo-3,5-dimethoxyphenyl)propan-1-one as an orange oil (1.09 g, 56% yield).
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