2-(3-Ethoxycarbonylmethyloxy-4-phenylbenzylamino)-1-(β-D-ribofuranosyl)-1H-benzimidazole (53 mg) was dissolved in tetrahydrofuran (5 mL). To the reaction mixture was added 2 mol/L aqueous sodium hydroxide solution (1 mL), and the mixture was stirred 60° C. for 1 hour. To the reaction mixture was added 2 mol/L hydrochloric acid (1 mL), and the solvent was removed under reduced pressure. The obtained residue was purified by preparative reverse phase column chromatography (Shiseido CAPSELL PAC C18UG80, 5 μm, 20×50 mm, flow rate 30 mL/minutes linear gradient, water/methanol=70/30-10/90) to give the title compound (20 mg).
