L-Tryptophan → (S)-3-(1H-Indol-3-yl)-2-(4-phenyl-butyrylamino)-propionic acid

Participants

Reaction Steps

(Method J15B) A suspension of L-tryptophan (2.040 g, 10 mmol) and NaHCO3 in water (15 ml) was treated with 4-phenyl-butyric acid 2,5-dioxo-pyrrolidin-1-yl ester (15/95) (2.610 g, 10 mmol) followed by the addition of acetonitrile (ca. 15 ml) to get a clear solution. The reaction mixture was stirred at ambient temperature for 12 hours and acetonitrile was removed under reduced pressure. The residue was acidified with citric acid to pH 2 and extracted with ethyl acetate (100 ml). The organic layer was washed with water (2×20 ml), brine (20 ml), and dried (MgSO4). The solvents were evaporated to give the crude product 16/95 (3.160 g, 95%). 1H NMR (DMSO-d6, HMDSO) δ: 1.51-1.82 (2H, m); 1.96-2.24 (2H, m); 2.33-2.64 (2H, m); 2.80-3.38 (2H, m); 4.38-4.68 (1H, m); 6.82-7.66 (14H, m); 8.11 (1H, d, J=8.0 Hz); 10.87 (1H, m).

Provenance & Evidence