Trifluoroacetic acid → HCID 178462112, compound

Participants

Reaction Conditions

Reaction Steps

Trifluoroacetic acid (7 ml) was added to a solution of (2R,S,3S)N2-tert-butoxycarbonyl-N-(tetrahydro-2-benzyloxy-5-oxo-3-furanyl)-L-alaninamide (14) (1.00 g, 2.64 mmol) in dichloromethane (7 ml) at 0° C. The mixture was stirred at 0° C. for 75 min. The mixture was concentrated, and the residue treated with diethyl ether then the ether was removed under vacuum. This procedure was repeated twice to yield a pale yellow glass. The solid was dissolved in DMF (20 ml). Diisopropylethylamine (1.38 ml, 7.92 mmol) followed by 4-(3-phenylpropyl)imidazole-2-carboxylic acid (13d) (0.67 g, 290 mmol), 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride (0.56 g, 2.90 mmol) and hydroxybenzotriazole (0.71 g, 5.28 mmol) were then added to this solution. The mixture was stirred at room temperature for 20 h then poured into brine. The mixture was extracted with ethyl acetate (3×50 ml). The combined organic extracts were washed with saturated aqueous sodium bicarbonate (2×100 ml) then brine (2×100 ml), dried (MgSO4), filtered and concentrated. The residue was purified by column chromatography (ethyl acetate) to afford 0.99 g (76%) of 17d as a mixture of diastereomers: IR (KBr) 3293, 3064, 2937, 1793, 1650, 1530, 1451, 1446, 1119; 1H NMR (CDCl3) δ 7.96 (brm), 7.62 (brd), 7.36-7.10 (10H, m), 6.88 (s), 6.86 (s), 5.53 (d, J=5.2), 5.48 (s), 4.87-4.52 (4H, m), 3.11-2.38 (2H, m), 2.65 (4H, m), 1.99 (2H, m), 1.47 (d, J=6.9), 1.46 (d, J=7.0).

Provenance & Evidence