[CH:1]1([CH2:6][C@@H:7]2[CH2:10][N:9]([O:11][CH2:12][C:13]3[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=3)[C:8]2=[O:19])[CH2:5][CH2:4][CH2:3][CH2:2]1.[OH:20][Li].O.Cl.[OH-].[Na+]>C1COCC1.O>[CH:1]1([CH2:6][C@H:7]([CH2:10][NH:9][O:11][CH2:12][C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[C:8]([OH:19])=[O:20])[CH2:5][CH2:4][CH2:3][CH2:2]1A mixture of (3R)-3-(cyclopentylmethyl)-1-[(phenylmethyl)oxy]-2-azetidinone (20 g, 77.1 mmol) and LiOH.H2O (32.4 g, 0.77 mol) in THF/water (500 mL/170 mL) was stirred at room temperature for 36 h. To the reaction mixture was added 6M HCl (130 mL), and then 1 N NaOH was added until a neutral pH was obtained. The layers were separated, and the aqueous layer was extracted once with EtOAc. The combined organics were dried (MgSO4) and concentrated to provide (2R)-3-cyclopentyl-2-({[(phenylmethyl)oxy]amino}methyl)propanoic acid (22.85 g, >100%) as a clear, colorless oil. LCMS: (M+H)+: 277.9.
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