3-Hydroxybenzaldehyde → (1RS,3SR)-1-(3-hydroxy-phenyl)-6-ethoxy-3-methyl-2,3,4,9-tetrahydro-1H-beta-carboline-3-carboxylic acid methyl ester

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Reaction Steps

A mixture of (+/−)-2-amino-3-(5-ethoxy-1H-indol-3-yl)-2-methyl-propionic acid methyl ester (829 mg, 3 mmol), 3-hydroxybenzaldehyde (439 mg, 3.6 mmol) and trifluoroacetic acid (223 μl, 3 mmol) in dry dichloromethane (40 ml) is stirred for 6 h under argon. Methanol (2 ml) is added to dissolve the precipitated product and the mixture is diluted with dichloromethane (150 ml). It is washed with saturated aqueous NaHCO3 (2×50 ml) and water (2×50 ml), is dried, and the solvent is removed under reduced pressure. The residue is purified by column chromatography (dichloromethane-ethyl acetate, 7:1→4:1) to provide (1RS,3SR)-1-(3-hydroxy-phenyl)-6-ethoxy-3-methyl-2,3,4,9-tetrahydro-1H-beta-carboline-3-carboxylic acid methyl ester (1.05 g, 93%). M.p. 173-175° C. (from ethyl acetate-hexane).

Provenance & Evidence