[C:1]([O:5][C:6]([NH:8][CH2:9][CH2:10][O:11][NH:12][C:13]([C@@H:15]1[CH2:20][CH2:19][C@@H:18]([NH:21][O:22][CH2:23][C:24]2[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=2)[CH2:17][N:16]1C(=O)C(F)(F)F)=[O:14])=[O:7])([CH3:4])([CH3:3])[CH3:2].O.[OH-].[Na+].C(O)(=O)C>O1CCOCC1>[C:1]([O:5][C:6]([NH:8][CH2:9][CH2:10][O:11][NH:12][C:13]([C@@H:15]1[CH2:20][CH2:19][C@@H:18]([NH:21][O:22][CH2:23][C:24]2[CH:25]=[CH:26][CH:27]=[CH:28][CH:29]=2)[CH2:17][NH:16]1)=[O:14])=[O:7])([CH3:4])([CH3:2])[CH3:3](2S,5R)—N-(2-tert-butoxycarbonylaminoethoxy)-5-(benzyloxyamino)-1-(2,2,2-trifluoroacetyl)piperidine-2-carboxamide (1.07 g, 2.06 mmol) was dissolved in 1,4-dioxane (4.2 mL), to which was added water (1.1 mL), and followed by ice cooling. To this was added 1M sodium hydroxide aqueous solution (6.3 mL), and followed by reaction at the same temperature for 2.5 h. pH was adjusted to ca. pH 7 by the addition of acetic acid to the reaction mixture. The organic solvent was distilled off under reduced pressure. The resulting aqueous solution was extracted with ethyl acetate. After the organic layer was washed with saturated brine, and dehydrated with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The resulting oil residue was purified by silica gel column chromatography (ethyl acetate/methanol=9/1) to afford 0.80 g of the title compound (yield 93%).
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