A mixture of 4-(benzyloxy)-6-bromo-2-methyl-1-[(4-methylphenyl)sulfonyl]-1H-benzimidazole (53.0 g, 112 mmol, Step 2) and tetrakis(triphenylphosphine)palladium (25.9 g, 22.4 mmol) in 2 mol/L dimethylamine tetrahydrofuran solution (580 mL) was stirred at 65° C. under carbon monoxide gas (1 atm) for 32 hours. The mixture was cooled to room temperature, and diluted with ethyl acetate. The organic mixture was washed with saturated ammonium chloride aqueous solution and brine, dried over magnesium sulfate and concentrated in vacuum. The residue was purified by column chromatography on silica gel eluting with hexane/ethyl acetate (gradient elution from 1:2 to 1:3) to afford the title compound as a white solid (21.8 g, 42%).
