The compound (521.6 mg) obtained in Example 39-1 was dissolved in methanol (15 ml) and added with hydrazine monohydrate (0.11 ml), followed by stirring at 60° C. for 1.5 hours. The reaction solution was added with a 1 mol/l sodium hydroxide aqueous solution and then subjected to extraction with chloroform. Subsequently, the organic layer was washed with saturated saline solution and then dried with anhydrous sodium sulfate. After the solvent had been distilled off, the subject compound (372 mg) was obtained as a yellow solid.
