Reaction Steps
Prepared from 3-allyloxycarbonylamino-4-hydroxy-butyric acid tert-butyl ester (5.2 g, 20 mmol) as described for 40 using chloroethanol (4.05 mL, 60 mmol) to afford 1.84 g (35% yield) of the title compound as a mixture of epimers. For the anti-diastereomer: 1H-NMR (500 MHz, CDCl3) δ 2.42 (dd, J=18.1 Hz, 1H), 3.00 (dd, J=18.1, 7.8 Hz, 1H), 3.63 (m, 2H), 3.85 (m, 1H), 4.02 (m, 1H), 4.23 (m, 1H), 4.57 (br s, 2H), 5.17 (br s, 1H), 5.22 (d, H=11.5 Hz, 1H), 5.29 (d, J=16.8 Hz, 1H), 5.44 (s, 1H), 5.89 (m, 1H) ppm; LC-MS (ES+) m/e=264 (M+H). For the syn-diastereomer: 1H-NMR (500 MHz, CDCl3) δ 2.47 (dd, J=17.3, 10.7 Hz, 1H), 2.83 (dd, J=17.3, 8.4 Hz, 1H), 3.65 (m, 2H), 3.83 (m, 1H), 4.11 (m, 1H), 4.57 (m, 3H), 5.22 (d, H=10.4 Hz, 1H), 5.30 (d, J=17.2 Hz, 1H), 5.33 (m, 1H), 5.47 (d, J=5.2 Hz, 1H), 5.89 (ddt, J=17.1, 11.0, 5.4 Hz, 1H) ppm; LC-MS (ES+) m/e=264 (M+H).
