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 compound 3 (2.6 g, 12.3 mmol) in DMF was added HOBt.H2O (2.26 g, 14.76 mmol), EDC.HCl (2.80 g, 14.76 mmol), HCl.H-Phe-NH2 (3.16 g, 14.76 mmol), triethylamine (1.72 mL, 12.3 mmol) sequentially at 0° C. and the mixture was stirred for 14 h at room temperature. After the solvent was removed in vacuo, the residue was dissolved in AcOEt and washed with 5% citric acid, 5% NaHCO3 and saturated NaCl for three times, respectively. Then, the organic layer was dried over Na2SO4 and evaporated in vacuo. The resultant crude product was purified by silica-gel column chromatography (CHCl3:MeOH=100:1 to 10:1) to obtain the desired compound 4; yield 1.9 g (43.4%); m.p. 49-53° C.; 1H NMR (300 MHz, CDCl3) δ 11.04 (s, 1H), 7.82 (s, 1H), 7.34-7.22 (m, 5H), 6.24 (s, 1H), 5.96 (br s, 1H), 5.45 (br s, 1H), 4.78-4.71 (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