At room temperature, 2-methyl-3-bromo-5-fluorobenzoic acid (4.2 g, crude) was dissolved in methanol (16 mL) and thionyl chloride (2.5 mL) was added slowly. The reaction mixture was heated to 70 °C with continuous stirring for 3 hours. Upon completion of the reaction, the mixture was cooled to room temperature and the solvent was removed under reduced pressure by rotary evaporator to give the crude product. The crude product was purified by silica gel column chromatography with the eluent of petroleum ether/ethyl acetate (50:1, v/v) to afford methyl 3-bromo-5-fluoro-2-methylbenzoate (2.3 g, 51% yield) as a yellow oil.
