General procedure for the synthesis of 2-piperidinecarboxamide from 1-N-benzyloxycarbonyl-2-piperidinecarboxylic acid:[Ref. Example 19] To a dichloromethane (20 mL) containing N-benzyloxycarbonylpiperidine-2-carboxylic acid (2.0 g), 1-hydroxybenzotriazole (1.6 g), and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.3 g) at room temperature Concentrated ammonia (3 mL) and triethylamine (2 mL) were added to the solution, followed by stirring the reaction mixture for 3 days. Upon completion of the reaction, the mixture was partitioned between water and dichloromethane. The organic layer was dried with anhydrous magnesium sulfate, filtered and the solvent was evaporated under reduced pressure. The residue was dissolved in methanol (30 mL), 10% palladium-carbon catalyst (1 g, 50% wet) was added and stirred under hydrogen atmosphere for 20 hours. At the end of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to give the 2-piperidinecarboxamide solid product (970 mg, quantitative yield). m/z MS (ESI): 128 (M+).
