L-Hydroxyproline → 4-Hydroxy-L-proline methyl ester hydrochloride

Participants

Reaction Steps

To a suspension of trans-4-hydroxy-L-proline (200 g: 1.525 mole) in methanol (800 ml), acetylchloride (163 ml: 2.288 mole) is added dropwise under ice cooling in a nitrogen atmosphere. The mixture is warmed to room temperature, mixed with thionyl chloride (55.7 ml: 0.763 mole), and stirred for 4 hours at 40° C. to give (2S,4R)-4-hydroxy-2-methoxycarbonylpyrrolidine hydrochloride (244.27 g). Yield: 88%. Colorless crystals. NMR δ(D2O) ppm: 1.8 to 2.0(m, 1H), 2.0 to 2.2(m, 1H), 2.9 to 3.1(m, 1H), 3.17(dd, J=12.6 Hz, J=3.6 Hz, 1H), 3.49(s, 3H), 4.2 to 4.4(m, 2H). IR ν (KBr) cm-1 : 3380, 3330, 2695, 2960, 1742.

Provenance & Evidence