GENERAL STEPS: To a suspension of N-Boc-4-piperidone (10.00 g, 50.19 mmol) in ethanol (75 mL) was added 10% Pd/C catalyst (1.00 g, 10 wt%), methylamine (33% ethanol solution, 27 mL, 0.20 mol) and formic acid (46 mg, 1.00 mmol). The reaction mixture was placed in an autoclave, sealed under a hydrogen atmosphere at 4 MPa and stirred at 50°C overnight. After completion of the reaction, it was cooled to room temperature and filtered to remove the catalyst. The filtrate was concentrated in vacuum to afford 1-Boc-4-(methylamino)piperidine as a pale yellow liquid (10.70 g, 99% yield). Mass spectrum (ESI, cation mode) m/z: 215.3 [M + H]+; 1H NMR (400 MHz, CDCl3): δ (ppm) 4.01 (m, 2H), 2.79 (m, 2H), 2.48 (m, 1H), 2.42 (s, 3H), 1.83 (m, 2H), 1.44 (s, 9H), 1.28-1.15 (m, 2H).
