A mixture of 3,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-dibenzo[b,d]thiophene (3.6 g, 8.2 mmol), (S)-tert-butyl 2-(6-bromo-1H-benzo[d]imidazol-2-yl)pyrrolidine-1-carboxylate (1.0 g, 2.7 mmol), tetrakis(triphenylphosphine)palladium(0) (0.31 mg, 0.27 mmol), 2M aqueous potassium carbonate solution (5 mL, 10 mmol), dimethoxyethane (25 mL), toluene (5 mL) and dichloroethane (2.5 mL) was degassed under a stream of argon for 15 minutes. The reaction was heated to 85° C. for 2 hours. Upon completion, the reaction was cooled to room temperature, diluted with ethyl acetate and filtered through Celite. The filtrate was washed with water and brine, dried (MgSO4) and concentrated. The resulting crude material was purified by flash column chromatography to yield (S)-tert-butyl 2-(6-(7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzo[b,d]thiophen-3-yl)-1H-benzo[d]imidazol-2-yl)pyrrolidine-1-carboxylate (1.0 g, 62%).
