Ammonium Hydroxide → HCID 178501363, compound

Participants

Reaction Steps

To a solution of (R)-2-benzyloxycarbonylamino-3-(3,4-diamino-phenyl)-propionic acid methyl ester mono acetate (2.68 g, 6.65 mmol) in acetic acid (30 mL) and water (40 mL), at room temperature was added a solution of sodium nitrite (0.46 g, 6.65 mmol) in water (8 mL), dropwise over several minutes. The resulting mixture was stirred at room temperature for 20 min, then cooled to 0° C., concentrated ammonium hydroxide was added to adjust pH to 11. The mixture was extracted with ethyl acetate twice in the presence of solid sodium chloride, and the organic layers were dried over sodium sulfate. After filtration, solvents were removed in vacuo and the residue was purified by chromatography on silica gel using ethyl acetate/hexanes (6:4) as eluent to afford the title compound as a tan solid (94% yield). 1H-NMR (CD3OD, 500 MHz) δ 7.75 (d, J=8.5 Hz, 1H), 7.58 (s, 1H), 7.31–7.25 (m, 5H), 7.18 (d, J=8.5 Hz, 1H), 5.39 (d, J=8.0 Hz, 1H), 5.10 (d, J=12.0 Hz, 1H), 5.05 (d, J=12.0 Hz, 1H), 4.74 (dd, j=13.5, 6.0 Hz, 1H), 3.73 (s, 3H), 3.34 (dd, J=14.0, 5.5 Hz, 1H), 3.22 (dd, J=13.5, 6.0 Hz, 1H). 13CNMR (CD3OD, 125 MHz) δ 172.1, 156.0, 136.1, 128.6, 128.3, 128.1, 67.2, 55.2, 52.7, 38.5. Mass spec. 355.18 (MH)+.

Provenance & Evidence