C(C1COC(=O)N1[C:14](=[O:33])[CH:15]([CH2:27][CH:28]1[CH2:32][CH2:31][CH2:30][CH2:29]1)[CH2:16][N:17]([O:20][CH:21]1[CH2:26][CH2:25][CH2:24][CH2:23][O:22]1)[CH:18]=[O:19])C1C=CC=CC=1.C1C[O:37]CC1.O.OO>[Cl-].[Na+].O>[CH:28]1([CH2:27][CH:15]([CH2:16][N:17]([CH:18]=[O:19])[O:20][CH:21]2[CH2:26][CH2:25][CH2:24][CH2:23][O:22]2)[C:14]([OH:33])=[O:37])[CH2:29][CH2:30][CH2:31][CH2:32]1N-[3-(4-Benzyl-2-oxo-oxazolidin-3-yl)-2-cyclopentylmethyl-3-oxo-propyl]-N-(tetrahydro-pyran-2-yloxy)-formamide (3.65 g, 7.96 mmol), THF (125 mL), and water (40 mL) is cooled to 4° C. To this mixture, is added 30% H2O2 (5.2 mL, 50.90 mmole) and LiOH monohydrate (0.40 g, 9.53 mmol), respectively. The reaction mixture is stirred for 1.5 hours. The mixture is slowly quenched with 0.5 M Na2SO3, while maintaining the temperature below 15° C. with an ice bath. The quenched mixture is stirred for an addition 30 minutes, concentrated in vacuo until the THF solvent is removed, and washed with EtOAc. The basic reaction mixture is acidified with Amberlite IR-120 resin (H+) to pH=4.5. Brine is added to the acidic solution, and the combined mixture is extracted with EtOAc. The organic layers from the acidic solution washing are combined, dried over Na2SO4, and concentrated in vacuo. This gave 2-cyclopentylmethyl-3-[formyl-(tetrahydro-pyran-2-yloxy)-amino]-propionic acid (1.20 g, 50% yield) as an oil.
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