The reaction mixture of 3-bromo-5-(2H-tetrazol-5-yl)pyridine (226 mg, 1.0 mmol, 1 eq), 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine (316 mg, 1.15 eq), triphenylphosphine (53 mg, 0.2 eq), and palladium diacetate (22 mg, 0.1 eq) in dioxane (3 mL) and aqueous sodium carbonate (2 M, 2 mL, 4 eq) under nitrogen atmosphere was vigorously stirred and heated at 100° C. for three hours. It was then cooled to room temperature, filtered through a Buchner funnel, and rinsed with small amount of water and ethyl acetate. The filtrate was isolated and concentrated down with silica gel. Upon a gradient column chromatography (EtOAc to MeOH-EtOAc 1:4), 2-(5-(2H-tetrazol-5-yl)pyridin-3-yl)benzo[b]thiophen-5-amine was obtained as an orange colored solid in the amount of 92 mg while the starting material, 3-bromo-5-(2H-tetrazol-5-yl)pyridine was recovered in the amount of 90 mg.
