Methanol → (4R)-4-Hydroxy-L-proline methyl ester

Participants

Reaction Steps

Thionyl chloride (5.6 mL, 76.3 mmol) was added dropwise to dry methanol (76 mL) at −20° C., following by addition of trans-4-hydroxy-L-proline (5.0 g, 38.1 mmol). The resulting mixture was allowed to warm to rt and stirred for 20 h. The solvent was removed under reduced pressure, and the residue was further dried under high vacuum to provide trans-4-hydroxy-L-proline methyl ester 1 as a white solid: 1HNMR (300 MHz, DMSO-d6) δ 2.18-2.23 (m, 2H), 3.06 (m, 1H), 3.32-3.36 (m, 2H), 3.76 (s, 3H), 4.42 (br. s, 1H), 4.48 (dd, J=5.4, 8.1 Hz, 1H), 5.56 (br. s, 1H); EIMS m/z 146 ([M]++1).

Provenance & Evidence