[Cl:1][C:2]1[N:3]=[C:4]([C:9]([NH:11][CH:12]2[CH2:15][N:14]([C:16]3[S:17][C:18]([C:22]([O:24]CC)=[O:23])=[C:19]([CH3:21])[N:20]=3)[CH2:13]2)=[O:10])[NH:5][C:6]=1[CH2:7][CH3:8].[OH-].[Li+].C1COCC1.O>CO>[Cl:1][C:2]1[N:3]=[C:4]([C:9]([NH:11][CH:12]2[CH2:13][N:14]([C:16]3[S:17][C:18]([C:22]([OH:24])=[O:23])=[C:19]([CH3:21])[N:20]=3)[CH2:15]2)=[O:10])[NH:5][C:6]=1[CH2:7][CH3:8]Ethyl 2-(3-{[(4-chloro-5-ethyl-1H-imidazol-2-yl)carbonyl]amino}azetidin-1-yl)-4-methyl-1,3-thiazole-5-carboxylate obtained in Example (218c) (145 mg, 0.36 mmol) was dissolved in methanol (3.6 mL). A 2 N aqueous lithium hydroxide solution (1.82 mL, 3.64 mmol) was added, and the mixture was stirred at room temperature for 27 hours. THF (2 mL) was added, followed by further stirring for 22 hours. Water was added to the reaction solution, and then the mixture was washed with ethyl acetate. A 1 N aqueous hydrochloric acid solution (4 mL) was added to the aqueous layer, followed by extraction with a chloroform/methanol mixed solvent. The combined organic layers were dried over anhydrous magnesium sulfate and then filtered, and the filtrate was concentrated under reduced pressure. The resulting solid was suspended and washed in diethyl ether to obtain 123 mg of the title compound as a white solid (91%).
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