Hydrochloric Acid → 3-(5-tert-Butyloxazol-4-yl)-N-((S)-1-carbamoyl-2-phenylethyl)-2-hydroxyacrylamide

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Reaction Steps

To a solution of the compound from Example 6 (2.61 g, 12.3 mmol) in DMF were added HOBt.H2O (2.26 g, 14.76 mmol), EDC.HCl (2.8 g, 14.76 mmol), HCl.H-Phe-NH2 (3.16 g, 14.76 mmol) and Et3N (1.72 mL, 12.3 mmol) and the reaction mixture was stirred for 14 h at room temperature. After removal of the solvent, the residue was dissolved in AcOEt, successively washed with 10% citric acid, 5% NaHCO3 and saturated NaCl for three times, dried over Na2SO4, and concentrated in vacuo to obtain the title compound: yield 2.26 g (43%); mp 50-53° C., 1H NMR (300 MHz, CDCl3) δ 11.04 (s, 1H), 7.81 (d, J=0.6 Hz 1H), 7.74-7.21 (m, 5H), 6.62 (d, J=0.7 Hz 1H), 6.00 (s, 1H), 5.52 (s, 1H), 4.79-4.72 (m, 1H), 3.24-3.11 (m, 2H), 1.38 (s, 9H); HRMS (EI): m/z 357.1689 (M+) (calced for C19H23N3O4: 357.1688).

Provenance & Evidence