Synthesis
General procedure for the synthesis of pyrrolidine-2-methanol from DL-proline: DL-proline (6.0 g, 52.0 mmol) was slowly added in batches to a THF (80 mL) suspension of LiAlH4 (3.0 g, 78.0 mmol) under stirring at 0 °C and nitrogen protection, and the addition process was controlled to be completed within 30 min. The reaction mixture was gradually warmed up to room temperature and then continued to be heated and refluxed for 3 hours. Upon completion of the reaction, a 20% KOH solution (18-20 mL) was slowly added at 0 °C to quench the reaction. The mixture was filtered through a Celite pad and the filter cake was washed with THF. The solid obtained by filtration was again mixed with THF and filtered at reflux for 30 min. All the filtrates were combined and concentrated to give the light yellow liquid product K1 (3.2 g, 65% yield), which gradually transformed to a dark brown liquid during storage. The Rf value of the product was 0.1 (unfolding agent: DCM solution of 10% MeOH containing 1 drop of AcOH, ninhydrin color developed).
References
[1] Tetrahedron, 2010, vol. 66, # 40, p. 7970 - 7974
[2] Patent: WO2015/181676, 2015, A1. Location in patent: Page/Page column 166-167
[3] Patent: WO2011/22508, 2011, A2. Location in patent: Page/Page column 59
[4] Hoppe-Seyler's Zeitschrift fuer Physiologische Chemie, 1931, vol. 203, p. 279,285
[5] Monatshefte fuer Chemie, 1952, vol. 83, p. 541
