[OH:1][C@H:2]1[CH2:7][CH2:6][N:5]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[CH2:4][C@H:3]1[CH3:15].[H-].[Na+].[CH3:18]I>CN(C=O)C>[CH3:18][O:1][C@H:2]1[CH2:7][CH2:6][N:5]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[CH2:4][C@H:3]1[CH3:15]To a solution of racemic (cis)-tert-butyl 4-hydroxy-3-methylpiperidine-1-carboxylate (310 mg, 1.44 mmol) (CAS#955028-93-0; prepared as described in US 20070249589)] in DMF (5 mL) at 0° C. was added NaH (60% dispersion in mineral oil, 75 mg, 1.87 mmol). The reaction mixture was stirred at 0° C. for 10 minutes and MeI (0.13 mL, 2.02 mmol) was added. After 2 h the reaction was quenched with saturated aqueous NH4Cl. The aqueous phase was washed three times with EtOAc. The combined organic extracts were washed with brine, dried over Na2SO4, filtered, and concentrated. The resulting residue was purified by silica gel flash chromatography (0-100% EtOAc/heptanes) to provide racemic (cis)-tert-butyl 4-methoxy-3-methylpiperidine-1-carboxylate. 1H NMR (400 MHz, CDCl3) δ ppm 3.36-3.50 (m, 6 H), 3.34 (dt, J=6.6, 3.3 Hz, 1 H), 3.22-3.29 (m, 1 H), 1.78-1.96 (m, 2 H), 1.49 (s, 9 H), 0.95 (d, J=6.8 Hz, 3 H).
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