A) General procedure for synthesizing methyl 5-bromo-2-hydroxy-4-methoxybenzoate: to a solution of 5-bromo-2-hydroxy-4-methoxybenzoic acid (2.00 g) in methanol (10.0 mL) was slowly added a solution of 0.6 M (diazomethyl)trimethylsilane in hexanes (14.8 mL) under cooling conditions in an ice bath. The reaction mixture was stirred at room temperature for 3 hours. Upon completion of the reaction, acetic acid (0.12 mL) was added to quench the reaction, followed by evaporation of the solvent under reduced pressure. The resulting crude product was purified by silica gel column chromatography (eluent: ethyl acetate/hexane) to afford the target compound methyl 5-bromo-2-hydroxy-4-methoxybenzoate (2.08 g). The product was characterized by 1H NMR (300 MHz, CDCl3) with chemical shifts of δ3.91 (3H, s), 3.93 (3H, s), 6.49 (1H, s), 7.99 (1H, s), 10.93 (1H, s).
