To a stirred solution of methyl 4-(3,4-dihydro-2H-chromen-4-yloxy)-1,2-dimethyl-1H-benzimidazole-6-carboxylate (1.0 g, 2.8 mmol, STEP 1) in methanol (20 mol) and tetrahydrofuran (30 mL) was added 4M lithium hydroxide aqueous solution (4 mL, 16 mmol) at room temperature. After stirring for 5 hours at 60° C., the reaction mixture was concentrated in vacuum. The residue was dissolved with water and acidified (pH=3) with 2M hydrochloric acid. The resulting precipitate was filtrated, and dried in vacuum to afford the title compound as a white solid (0.85 g, 89%):
