3184-13-2

42538-31-8

General procedure for the synthesis of 3-(S)-amino-2-piperidone hydrochloride from L-ornithine hydrochloride: trimethylchlorosilane (2.8 mL, 23 mmol, 4 eq.) was slowly added to L-ornithine hydrochloride (1.0 g, 6.0 mmol, 1 eq.), followed by anhydrous methanol (20 mL). The reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, the solution was cooled to 0 °C and an ethanol solution of 21% (w/w) sodium ethanol (42 mmol, 17 mL) was added dropwise. after 5 min, the reaction system was slowly warmed up to room temperature and stirring was continued for 30 min. The pH of the reaction solution was adjusted with aqueous 6N HCl to 7. The neutralized solution was filtered and the filtrate was concentrated under reduced pressure. The crude product was concentrated again under reduced pressure to remove salts by dissolving in isopropanol and filtering to remove insoluble matter. Finally, the crude product was purified by silica gel fast column chromatography (eluent: 30% methanol/dichloromethane) to afford the target compound 3-(S)-amino-2-piperidone hydrochloride as a hygroscopic light yellow solid.