Water → HCID 18536711, compound

To a suspension of the compound of Example 18 (1.13 g, 1.97 mmol) in ethanol (30 ml) was added 1 mol/L aqueous solution of lithium hydroxide (9.26 ml, 9.26 mmol) and successively water (15 ml), and, after stirring for 4 hours at room temperature, the mixture was allowed to stand statically overnight. After stirring for 16 hours at 30° C., ice water was added to the reaction mixture and the insolubles were filtered off. Then, the pH value was brought to 4 with 3 mol/L hydrochloric acid and solvent was distilled off. Water was added to the residue obtained, the precipitated crystals were collected by filtration, washed with water, and then dried under reduced pressure. After the powder obtained was suspended into water (40 ml), 1 mol/L aqueous solution of lithium hydroxide (9.26 ml, 9.26 mmol) was added and the mixture was stirred for 30 minutes at 50° C. Ice water was added to the reaction mixture, the insolubles were filtered off, then the pH value was brought to 4 with 3 mol/L hydrochloric acid, and solvent was distilled off. Water was added to the residue obtained, the precipitated crystals were collected by filtration, washed with water, and then dried under reduced pressure, thereby obtaining 757 mg of title compound as pale yellow powder.