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

Participants

Reaction Steps

To a stirred solution of (2S,4R)-4-hydroxypyrrolidine-2-carboxylic acid (13.1 g, 0.1 mol) in methanol (400 mL) cooled to 0° C. was added acetyl chloride (14.3 mL, 0.2 mol) over a period of 30 min. The reaction mixture was warmed to room temperature and stirred for 2 h. The volatiles were removed under reduced pressure and the residue was triturated with ether several times to get methyl (2S,4R)-4-hydroxypyrrolidine-2-carboxylate hydrochloride salt as a white powder (14.5 g) in 100% yield. m/z (M+1) 145; 1H NMR (DMSO-d6) 300 MHz δ 5.7-5.5 (s (br), 1H), 4.55-4.35 (m, 2H), 3.76 (s, 3H), 3.35 (d, J=12 Hz 1H), 3.10 (d, J=12 Hz 1H), 2.25-2.0 (m, 2H).

Provenance & Evidence