The general procedure for the synthesis of 2,5-dimethylphenylboronic acid from trimethyl borate, 2,5-dimethylbromobenzene and aqueous electrophoretic grade was as follows: 1-bromo-2,5-dimethylbenzene (25.0 g, 0.135 mol) was dissolved in 200 ml of tetrahydrofuran under the protection of nitrogen in a 1 L round-bottomed flask and cooled to -78 °C. A 1.6 M n-butyllithium solution was added slowly dropwise and the reaction was stirred for 2 hours keeping the temperature at -78 °C. Subsequently, trimethyl borate (18.2 g, 0.176 mol) was added dropwise and the reaction continued at the same temperature. After completion of the reaction, 1 equivalent of hydrochloric acid (101 ml, 0.162 mol) was added to acidify the reaction mixture at room temperature and stirred for 1 hour. The reaction solution was concentrated under reduced pressure and the resulting solid was recrystallized from hexane to give Intermediate 1-b (12.5 g, 62% yield).
