The general procedure for the synthesis of 4-phenylpiperidine hydrochloride from 4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride was as follows: 10% palladium carbon (100 mg) was added to a stirred solution of 4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (300 mg, 1.53 mmol) in methanol (10 mL) under argon protection. Subsequently, the reaction mixture was flushed with hydrogen three times and the reaction was stirred under hydrogen atmosphere (balloon) for 4 hours. The reaction progress was monitored by LCMS. After completion of the reaction, the reaction mixture was filtered through a short diatomaceous earth pad and washed with methanol (5 mL). The filtrate was concentrated under reduced pressure and the residue was washed with anhydrous ether (2 x 5 mL) to give the final 4-phenylpiperidine hydrochloride (300 mg, 99%) as an off-white hygroscopic solid. m/z 162.3 [M+H]+ by LCMS.
