反应详情

To a solution of (R)-tert-butyl 4-oxobutan-2-ylcarbamate (1.54 g, 8.22 mmol) in THF (25 mL) at rt was added (carbethoxymethylene)triphenylphosphorane (6.30 g, 18.1 mmol) in portions. The resulting clear solution was stirred at rt under argon for 3 days. The reaction mixture was concentrated and the oily residue was purified using silica gel chromatography (ISCO system) eluting with a gradient of 0-60% EtOAc/Hex to give (R,E)-ethyl 5-(tert-butoxycarbonylamino)hex-2-enoate (1.70 g, 6.61 mmol, 80% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ ppm 6.91 (dt, J=15.3, 7.5 Hz, 1H), 5.92-5.82 (m, 1H), 4.37 (s, 1H), 4.19 (q, J=7.1 Hz, 2H), 3.83 (s, 1H), 2.37 (t, J=6.6 Hz, 2H), 1.44 (s, 9H), 1.29 (t, J=7.1 Hz, 3H), 1.15 (d, J=6.7 Hz, 3H).

1. concentrationThe reaction mixture was concentrated
2. customthe oily residue was purified
3. washeluting with a gradient of 0-60% EtOAc/Hex