O=[CH:2][C@H:3]([NH:5][C:6](=[O:12])[O:7][C:8]([CH3:11])([CH3:10])[CH3:9])[CH3:4].Cl.[NH2:14][OH:15].N1C=CC=CC=1>CO>[OH:15][N:14]=[CH:2][C@H:3]([NH:5][C:6](=[O:12])[O:7][C:8]([CH3:11])([CH3:10])[CH3:9])[CH3:4]A mixture of (R)-tert-butyl 1-oxopropan-2-ylcarbamate (28.0 g, 81.0 mmol), hydroxylamine hydrochloride (11.2 g, 81.0 mmol), pyridine (60 mL), MeOH (100 mL) was stirred at rt overnight. The solvent was then evaporated. To the residue was added water (100 mL) and the mixture was extracted with DCM (3×200 mL). The combined organic phases were dried (Na2SO4) and concentrated. The crude residue was purified by flash column chromatography (petroleum ether:EtOAc, 4:1) to give (R)-tert-butyl 1-(hydroxyimino)propan-2-ylcarbamate (24.0 g, 79%). 1H NMR (DMSO-d6, 400 MHz) δ 10.63 (s, 1H), 7.20 (d, J=5.2 Hz, 1H), 4.12 (m, 1H), 1.38 (s, 9H), 1.15 (d, J=6.8 Hz, 3H).
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