Ethyl isocyanate → HCID 68725794, compound

Participants

Reaction Conditions

Reaction Steps

2-[(S)-3-(4-benzyloxy-3-hydroxy-phenyl)-2-tert-butoxycarbonylamino-propionylamino]-2-methyl-propionic acid methyl ester (1.2 mmol), was dissolved in dichloromethane (5 ml) and ethyl isocyanate (0.31 ml) added. A catalytic amount of DMAP was added and the solution was heated at 50° C. for 7 hours. The reaction mixture was evaporated to dryness and the crude product purified by chromatography on silica gel eluting with a mixture of ethyl acetate-hexane. 2-[(S)-3-(4-Benzyloxy-3-ethylcarbamoyloxy-phenyl)-2-tert-butoxycarbonylaminopropionyl-amino]-2-methyl-propionic acid methyl ester was obtained as a white crystalline solid, 410 mg; Rf 0.29 (ethyl acetate-hexane 1:1); NMR (500 MHz, CDCl3) 1.39 (ca 3H, s), 1.41 (ca 3H, s), 1.43 (ca 9H, s), 2.86 (1H, dd J 14, 8), 3.08 (1H, dd J 14, 5), 3.25-3.32 (2H, m), 3.70 (3H, s), 4.23 (1H, br), 5.00 (1H, br t J 5), 5.07 (2H, s), 6.15 (1H, s), 6.91 (1H, d J 8), 6.99-7.02 (2H, m), 7.28-7.42 (ca 5H, m); HPLC/MS retention time 5.98 min, m/z 558 (MH+).

Provenance & Evidence