(S)-3-N-Boc-3-(methylamino)piperidine

309962-62-7

74-88-4

309962-63-8

The product of Example 42A (1.78 g, 6.0 mmol) was dissolved in THF (30 mL) at 0 °C and NaH (0.360 g, 60% dispersion, 9.0 mmol) was added. After stirring for 20 min, iodomethane (1.12 mL, 18 mmol) was added dropwise to the mixture, followed by slow warming of the reaction system to room temperature. After continued stirring for 4 hours, methanol (5 mL) was slowly added to quench the reaction, followed by concentration of the reaction mixture under reduced pressure. The concentrated residue was dissolved in fresh methanol (50 mL) and 20% aqueous K2CO3 (5 mL) was added. After stirring at room temperature for 16 hours, the mixture was concentrated under reduced pressure. The residue was extracted by partitioning with dichloromethane (50 mL) and saturated saline (20 mL). The organic phase was separated, dried with anhydrous MgSO4, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol/ammonia, 95:5:0.5, v/v/v) to afford the title compound (S)-3-N-BOC-3-(methylamino)piperidine as a hygroscopic yellow solid (1.14 g, 93% yield). Mass spectrum (chemical ionization/NH3) m/z 215 ([M+H]+).