[O:1]=[C:2]1[CH2:6][CH2:5][CH2:4][N:3]1[C@H:7]1[CH2:12][CH2:11][C@H:10]([C:13]([O:15]C)=[O:14])[CH2:9][CH2:8]1.[OH-].[Na+].Cl.[Cl-].[Na+]>CO>[O:1]=[C:2]1[CH2:6][CH2:5][CH2:4][N:3]1[C@H:7]1[CH2:12][CH2:11][C@H:10]([C:13]([OH:15])=[O:14])[CH2:9][CH2:8]1Methyl trans-4-(2-oxo-pyrrolidin-1-yl)cyclohexanecarboxylate (39.15 g) obtained in Reference Example 113(3) dissolved in methanol (400 ml), and thereto is added 2 N aqueous sodium hydroxide solution (60 ml) and the mixture is stirred at room temperature for 3 hours. The reaction solution is adjusted to pH 1-2 by pouring 10% hydrochloric acid under ice-cooling, saturated with sodium chloride, and then extracted with chloroform. The organic layer is dried over sodium sulfate, and then evaporated to remove the solvent under reduced pressure. The resulting residue is suspended in a small amount of ethyl acetate, and diisopropyl ether is poured thereto, and the resulting crystals are collected by filtration. The crystals are washed with diisopropyl ether several times and dried to give the title compound (35.94 g).
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