Trifluoroacetic acid → 2-(6-Methoxy-1,3,4,9-tetrahydro-beta-carboline-2-sulfonylmethyl)-3-methylbutyric acid

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Reaction Steps

Trifluoroacetic acid (1 ml) was added to a solution of 2-(6-methoxy-1,3,4,9-tetrahydro-β-carboline-2-sulfonylmethyl)-3-methyl-butyric acid tert-butyl ester (237 mg) in dichloromethane (10 ml) at room temperature under nitrogen. The mixture was stirred for 2 h before being evaporated under reduced pressure. The residue was partitioned between 1M aqueous sodium hydroxide (15 ml) and diethyl ether (15 ml). The organics were extracted with 1M aqueous sodium hydroxide (15 ml). The combined aqueous portions were acidified to pH=5 with 10% citric acid and extracted with ethyl acetate (4×20 ml). The combined organics were washed with water (2×10 ml) and brine (10 ml), then dried (MgSO4), filtered and the solvent removed under reduced pressure to give, after chromatography (SiO2, 20:1 dichloromethane-methanol), the title compound (128 mg, 62%) as a white foam.

Provenance & Evidence