174543-78-3

664364-60-7

174543-78-3

Step C: 3-Benzyl 3-ethyl-3-methylpiperidine-1,3-dicarboxylate (3.0 g, 10.0 mmol) was dissolved in ethanol (15 mL) and aqueous LiOH solution (15.0 mL, 30.1 mmol) was added. The reaction mixture was stirred at 86 °C for 1 hour. After completion of the reaction, ethanol was removed by distillation under reduced pressure. Ether (30 mL) was added to the residue for extraction and the aqueous layer was separated. The aqueous layer was acidified to pH 3-4 with saturated potassium bisulfate solution and then extracted with ethyl acetate (50 mL). The organic layer was washed with brine and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure to give 1-(benzyloxycarbonyl)-3-methylpiperidine-3-carboxylic acid (2.6 g, 92% yield) as an oil.