General Description
Methyl pipecolinate hydrochloride is a hydrochloride salt of methyl piperidine-2-carboxylate (methyl pipecolinate). The kinetics of the enzymatic separation of enantiomeric forms of methyl pipecolinate using
Candida antarctica Lipase A (CAL-A) has been reported. Its role as catalyst for the standard Diels-Alder reaction has been examined.
Synthesis
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.
References
[1] European Journal of Organic Chemistry, 2014, vol. 2014, # 29, p. 6467 - 6480
[2] Patent: US2008/200471, 2008, A1. Location in patent: Page/Page column 38; 39
[3] Chemical and Pharmaceutical Bulletin, 1991, vol. 39, # 5, p. 1199 - 1212
[4] Tetrahedron Letters, 2006, vol. 47, # 29, p. 5017 - 5020
[5] Chemistry - A European Journal, 2010, vol. 16, # 25, p. 7547 - 7553
