Methyl 5-oxopyrrolidine-2-carboxylate (9 g, 62.93 mmol) was dissolved in methanol (150 mL) under argon protection, stirred and cooled to 0 °C. Subsequently, sodium borohydride (3.6 g, 95.2 mmol) was slowly added. The reaction mixture was gradually warmed to room temperature and stirring was continued for 2 hours. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming the complete consumption of raw materials, the reaction mixture was quenched with concentrated hydrochloric acid at 0°C. The reaction mixture was filtered and the solid was washed with methanol (2 x 50 mL). The filtrates were combined and concentrated under reduced pressure to remove the solvent. The crude product was purified by column chromatography with 10% methanol/dichloromethane as eluent to give 5-(hydroxymethyl)pyrrolidin-2-one (6 g, 83% yield) as a colorless oil. Liquid chromatography-mass spectrometry (LCMS) analysis showed that the [M+1]+ was 116; chromatographic conditions: X-Select CSH C-18 column (50×3.0 mm, 3.5 μm); mobile phase: 5 mM aqueous ammonium acetate/acetonitrile; flow rate: 0.80 mL/min; retention time (RT): 0.44 min. Thin-layer chromatography (TLC) analysis showed that the unfolding agent was 10% methanol/dichloromethane and the Rf value was 0.3.
