867044-33-5

760212-58-6

867044-33-5

Under argon protection, 10 g (29 mmol) of 1-(4-bromophenyl)-2-phenyl-1H-benzimidazole was dissolved in 100 mL of anhydrous tetrahydrofuran and the solution was cooled to -78 °C. Subsequently, 20 mL of n-butyllithium solution (1.6 mol/L, dissolved in hexane) was added slowly and dropwise. The reaction mixture was continuously stirred at -78 °C for 1 h and then warmed up to 0 °C. The mixture was again cooled to -78 °C and 9.7 mL (87 mmol) of trimethoxyborane was added dropwise. The mixture continued to be stirred at -78 °C for 1 hour, followed by 2 hours at room temperature. Upon completion of the reaction, 100 mL of 10% (w/w) hydrochloric acid solution was added and stirred for 1 hr, followed by filtration. The organic layer was separated, washed with saturated sodium chloride solution and dried with anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure and the residue was purified by silica gel column chromatography to give 4.2 g of [4-(2-phenyl-1H-benzimidazol-1-yl)phenyl]boronic acid in 46% yield.