The general procedure for the synthesis of 4-hydroxy-3-methylpiperidine from 1-benzyl-3-methylpiperidin-4-ol was as follows: N-benzyl-3-methylpiperidin-4-ol (5.16 g, 25.13 mmol) was dissolved in 50 mL of a solvent mixture of THF and MeOH (1:1, v/v), 20% Pd/C catalyst (0.5 g) was added, and the reaction was carried out at a hydrogen 50 psi pressure for 20 hours. Upon completion of the reaction, the crude product was filtered through diatomaceous earth and subsequently concentrated under vacuum conditions. The crude product (2.89 g, 99% yield) was analyzed by mass spectrometry (EI) to give m/z 116.0 (M + 1).
