To a solution of the compound 1 (665 mg) in ethanol (5 mL), 20% palladium hydroxide carbon (500 mg) was added under an argon atmosphere. The reaction mixture was stirred under a hydrogen gas atmosphere at 65° C. for 3 hours. The reaction mixture was filtered through Celite (trade name) and then concentrated. The obtained residue was purified by silica gel column chromatography (dichloromethane:methanol:28% ammonia water=10:1:0→80:10:1) to obtain the title compound (467 mg) having the following physical properties.
