General procedure for the synthesis of tert-butyl 2-methylpiperidin-3-ylcarbamate from N-Boc-2-methyl-3-aminopyridine: tert-butyl (2-methylpyridin-3-yl)carbamate (2.50 g, 12.00 mmol) was dissolved in 45 mL of glacial acetic acid in a 150 mL metal reactor and platinum(IV) oxide (420 mg, 1.85 mmol) and rhodium (5 wt%, Degussa type, 420 mg, 4.08 mmol). The reaction was hydrogenated at 70 °C and 200 psi hydrogen pressure for 23 hours. Upon completion of the reaction, the reaction mixture was filtered through a diatomaceous earth pad and the filter cake was washed with methanol (2 x 20 mL). The filtrates were combined and concentrated. The residue was adjusted to pH 9 with 2 N NaOH solution and extracted with ethyl acetate (3 x 75 mL). The organic phases were combined, washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated to give tert-butyl 2-methylpiperidin-3-ylcarbamate (1.67 g, 64.9% yield) as an off-white amorphous solid. Mass spectrum (ESI, cation mode) m/z: 215.1 ([M+H]+).
