Reaction Steps
A solution of Compound 9 (0.60 g, 1.62 mmol) in Ac2O (20 mL) was hydrogenated over 70 mg of 10 percent palladium on charcoal under atmospheric pressure. After 10 hours, the solution was filtered and the filtrate was concentrated in vacuo. By flash column chromatography with EtOAc-toluene (2.5:1), 0.52 g of Compound 10 was obtained in 83 percent yield. 1H NMR (CDCl3) δ6.03 (1H, d, J1-2=1.5 Hz, H-1), 5.34 (1H, dd, J3-4=10.0 Hz, J3-2=5.0 Hz, H-3), 5.18 (1H, t, J4-5=J4-3=10.0 Hz, H-4), 4.65 (1H, ddd, J5-4=10.0 Hz, J5-6a=5.0 Hz, J5-6b=2.0 Hz, H-5), 4.29 (1H, dd, J6a-6b12.5 Hz, J6a-5b=5 Hz, H-6a), 4.06 (1H, dd, J2-3=5.0 Hz, J2-1=1.5 Hz, H-2), 4.05 (1H, dd, J6b-6a=12.5 Hz, J6b-5=2.0 Hz, H-6b), 2.18 (3H, s, acetyl), 2.10 (3H, s, acetyl), 2.07 (3H, s, acetyl), 2.07 (3H, s, acetyl), 2.01 (3H, s, acetyl). 13C NMR (CDCl3) δ170.4, 170.1, 170.0, 169.6, 168.0, 91.7, 73.4, 70.1, 65.5, 62.1, 49.3, 23.2, 20.8, 20.7, 20.7, 20.6. HRMS (FAB) calcd for C16H23NO10Na (M+Na+) 412.1220, found 412.1224.
