5419-55-6

1160294-85-8

1133058-06-6

3-Bromo-6,9-diphenyl-9H-carbazole (4.8 g, 12.06 mmol) was dissolved in tetrahydrofuran (60 mL) and cooled to -78 °C. Under nitrogen protection, 2.5 M hexane solution of n-butyllithium (6.3 mL, 15.68 mmol) was slowly added dropwise, and stirring was continued at -78 °C for 1 h after completion of the drop. Subsequently, triisopropyl borate (4.5 g, 24.12 mmol) was slowly added and the reaction mixture was gradually warmed to room temperature and stirring was continued for 12 hours. Upon completion of the reaction, the reaction was quenched by slow dropwise addition of purified water (20 mL). The organic layer was separated by extraction with a mixture of dichloromethane and saturated aqueous ammonium chloride. The organic layer was concentrated and purified by silica gel column chromatography, and finally crystallized with a mixed solvent of dichloromethane/hexane to afford 6,9-diphenyl-9H-carbazol-3-yl-3-boronic acid (3 g, 70% yield).