(+-)-5-Hydroxytryptophan → 5-hydroxy-DL-tryptophan methyl ester hydrochloride

Participants

Reaction Steps

Thionyl chloride (2.14 mL, 29.4 mmol) was added dropwise to a slurry of 5-hydroxy-DL-tryptophan (3.8 g, 17.3 mmol) in anhydrous methanol (40 mL) at 0° C. under a nitrogen blanket. The resulting mixture was warmed slowly to room temperature and stirred for 17 hours. Then the solvent was removed under reduced pressure to provide 5-hydroxy-DL-tryptophan methyl ester hydrochloride (Intermediate 1) as a light brown foam (5.0 g, 100%): 1H NMR (300 MHz, DMSO-d6): δ 10.78 (bs, 1H), 8.62-8.25 (m, 3H), 7.18-7.11 (m, 2H), 6.79 (s, 1H), 6.67-6.61 (m, 1H), 4.18 (m, 1H), 3.69 (s, 3H), 3.25-3.12 (m, 2H).

Provenance & Evidence