[C:1]([CH:4]1[C:9](=O)[CH2:8][CH2:7][N:6](C(OC(C)(C)C)=O)[CH2:5]1)(=[O:3])[CH3:2].[NH2:18]O.Cl.O>CCO>[CH3:2][C:1]1[O:3][N:18]=[C:9]2[CH2:8][CH2:7][NH:6][CH2:5][C:4]=12A mixture of tert-butyl 3-acetyl-4-oxopiperidine-1-carboxylate (1.50 g) and NH2OH.HCl (0.50 g) in anhydrous EtOH was heated to reflux for 0.5 h. The reaction mixture was cooled to rt, and then poured into 20 mL of water. The resulted mixture was extracted with CH2Cl2 (20 mL×3). The combined organic phases were dried over Na2SO4 and concentrated in vacuo, the residue was chromatographed with a silica gel column (eluting agent: 10:1 (v/v) DCM/MeOH) to give the title compound as yellow oil (0.45 g, 52.00%), HPLC: 90.00%. The compound was characterized by the following spectroscopic data: MS (ESI, pos. ion) m/z: 139.3 (M+1); 1H NMR (400 MHz, CDCl3) δ: 2.31 (s, 3H), 2.86 (t, J=8.0 Hz, 2H), 3.15 (t, J=8.0 Hz, 2H), 3.92 (s, 2H) ppm.
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