5-(3-Bromo-phenyl)-1H-tetrazole 8b (20 g, 89 mmol) and 2-methoxybenzeneboronic acid (14.2 g, 93.3 mmol) were dissolved in 530 mL of 1,4-dioxane followed by addition of tetrakis(triphenylphosphine)palladium (1.84 g) and sodium carbonate (18.9 g, 178 mmol) under argon atmosphere. The reaction mixture was heated to reflux overnight. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was concentrated under reduced pressure to remove 1,4-dioxane and then hydrochloric acid (200 mL, 6 mol/L) was added. The mixture was cooled for 2 hours and the layers were separated. The organic layer was collected and concentrated. The residue was dissolved in 500 mL of ethyl acetate and washed with 250 mL of water. The mixture was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was dissolved in 25 mL of ethyl acetate and standing overnight. The mixture was filtered to obtain the title compound 5-(2′-methoxy-biphenyl-3-yl)-1H-tetrazole 8c (15 g, yield 68.2%) as a light yellow solid.
