To a 100 mL round-bottom flask was added 3-bromo-4-fluorobenzoic acid (5.00 g, 22.8 mmol, Oakwood), potassium carbonate (3.17 g, 22.9 mmol), and N,N-dimethylformamide (DMF, 30 mL). Subsequently, iodomethane (2 M in methyl tert-butyl ether (MTBE), 11.6 mL, 23.2 mmol) was slowly added and the reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the mixture was filtered and the filtrate was concentrated under reduced pressure. The obtained brown crude product was dissolved with ethyl acetate (EtOAc), filtered and concentrated again to finally obtain methyl 3-bromo-2-fluorobenzoate (4.76 g, 20.4 mmol, 89.5% yield) as a brown slurry, which could be used in subsequent steps without further purification.
