32559-18-5

67-56-1

4043-87-2

32559-18-5

Synthesis of methylpiperidine-2-carboxylic acid hydrochloride: methanol (1300 mL) was added to a 3000 mL three-necked round bottom flask. The reaction system was cooled to -30°C. Sulfoxide chloride (280 mL) was added slowly and dropwise under stirring conditions while keeping the temperature at -30 °C. Subsequently, piperidine-2-carboxylic acid (100 g, added in batches) was added to the reaction system and the mixture was cooled to 0 °C. The reaction was continuously stirred for 15 h at room temperature. The progress of the reaction was monitored by thin layer chromatography (TLC, the unfolding agent was methanol and a few drops of ammonia were added). After completion of the reaction, the reaction mixture was concentrated under vacuum using a rotary evaporator. Toluene (100 mL) was added to the concentrate and kept under reflux conditions. The mixture was again concentrated under vacuum using a rotary evaporator. This toluene addition and concentration step was repeated twice. The final product was 137 g (98% yield) of methylpiperidine-2-carboxylic acid hydrochloride as a white solid.