General procedure for the synthesis of 4-bromo-3-methoxybenzoic acid from methyl 4-bromo-3-methoxybenzoate: To a stirred solution of methyl 4-bromo-3-methoxybenzoate (11.2 g) in THF (130 mL) was added methanol (45 mL), water (45 mL), and a 1 M aqueous lithium hydroxide (140 mL) in sequence. The reaction mixture was stirred at room temperature for 1 hour. Upon completion of the reaction, the solvent was removed by rotary evaporator under reduced pressure. Water was added to the residue, followed by the dropwise addition of 1 N hydrochloric acid while cooling in an ice bath until the pH of the mixture reached 4. The precipitated solid product was collected by diafiltration, washed with water and dried under reduced pressure to give 10.1 g of the title compound 4-bromo-3-methoxybenzoic acid, which was used in the subsequent reaction without further purification.1H-NMR (300 MHz. DMSO-d6): δ[ppm] = 3.87 (s, 3H), 7.42 (dd, 1H), 7.50 (d, 1H), 7.68 (d, 1H), 13.21 (br s, 1H).
