114676-59-4

67-56-1

2584-71-6

114676-59-4

To a stirred solution of cis-4-hydroxy-D-proline (10.0 g, 76.3 mmol, 1 eq.) in methanol (300 mL) was slowly added thionyl chloride (10.0 mL, excess) over 1.5 min at 0 °C. The reaction mixture was gradually warmed to 23 °C and stirred continuously for 16 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure to afford (2R,4R)-4-hydroxypyrrolidine-2-carboxylic acid methyl ester hydrochloride as a white solid (15.9 g, 100% yield).