Reaction Steps
A mixture of tert-butyl N-[(3S,7S,8S,9S)-8-allyloxy-7-butoxy-9-methyl-2-oxo-1,5-dioxonan-3-yl]-N-tert-butoxycarbonylcarbamate (0.350 g, 0.698 mmol) and NaHCO3 (5.86 mg, 0.070 mmol) in MeOH (0.21 ml) and DCM (6.8 ml) was treated with ozone at −78° C. until the solution became light blue in color. The mixture was purged with nitrogen until colorless and quenched by the addition of DMS (0.10 ml, 1.40 mmol). The reaction mixture was slowly warmed to room temperature and stirred for 20 h. The mixture was concentrated and purified by flash chromatography on (SiO2, hexanes/EtOAc gradient) to yield the title compound as a colorless oil (320 mg, 91%): IR (neat) 2934, 2876, 1743, 1706, 1367, 1253, 1121, 1096 cm−1; 1H NMR (400 MHz, CDCl3) δ 9.63 (s, 1H), 5.18 (dd, J=8.9, 3.8 Hz, 1H), 4.84 (dq, J=9.4, 6.3 Hz, 1H), 4.39 (dd, J=17.9, 0.9 Hz, 1H), 4.22 (dd, J=17.8, 0.5 Hz, 1H), 4.19 (dd, J=12.2, 3.8 Hz, 1H), 3.91-3.75 (m, 2H), 3.57-3.42 (m, 2H), 3.37 (dt, J=9.2, 6.5 Hz, 1H), 3.29 (dd, J=7.9, 6.9 Hz, 1H), 3.21 (t, J=9.0 Hz, 1H), 1.52-1.40 (m, 2H), 1.45 (s, 18H), 1.41 (d, J=6.3 Hz, 3H), 1.30-1.19 (m, 2H), 0.83 (t, J=7.3 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ 200.51, 168.79, 152.61, 86.19, 83.52, 83.08, 79.09, 75.35, 72.95, 71.99, 70.03, 57.92, 32.02, 27.94, 19.29, 18.84, 13.85; HRMS-ESI (m/z) [M]+ calcd for C24H41NO10, 503.2730; found, 503.2727.
