The general procedure for the synthesis of 2,4-dimethoxyphenylboronic acid from 2,4-dimethoxybromobenzene was as follows: first, 576 μL of 1-bromo-2,4-dimethoxybenzene was dissolved in 5.8 mL of tetrahydrofuran, which was cooled to -78 °C under argon protection. Subsequently, 3 mL of 1.6 mol/L n-butyllithium hexane solution was slowly added dropwise. After the dropwise addition, 1.1 mL of triisopropyl borate was added and the reaction continued to be stirred at -78 °C for 40 minutes, after which it was brought to room temperature and stirred for 2 hours. Upon completion of the reaction, the reaction mixture was quenched by adding 40 mL of water and 1 mL of 5N hydrochloric acid to the reaction mixture and then extracted with 50 mL of ethyl acetate. The organic layer was dried with anhydrous magnesium sulfate and the solvent was removed by distillation under reduced pressure. Finally, 610.2 mg of 2,4-dimethoxyphenylboronic acid was purified by silica gel column chromatography (eluent ratio hexane:ethyl acetate=2:1). The product was characterized by 1H-NMR (CDCl3): δ (ppm) 3.85 (3H, s), 3.89 (3H, s), 5.81 (2H, s), 6.46 (1H, s), 6.56 (1H, dd, J = 2.0,8.4 Hz), 7.77 (1H, d, J = 8.4 Hz).
