반응 단계
Using a procedure similar to that described in Example 4 except replacing the propionic anhydride used therein with the requisite anhydride, the title compound 10 (0.04 g, 62%) was prepared as a white solid, mp 209-211° C.; 10 was synthesized as described for 9 from 8a using isobutyryl chloride to afford 0.04 g (62%) of 10 as a white solid, mp 209-211° C.; 1H NMR (CDCl3): δ 1.13 (3H, s, H-19); 1.24 (3H, d, J=6.9 Hz, CH3CH(CH3)CO2); 1.26 (3H, d, J=6.9 Hz CH3CH(CH3)CO2,); 1.46 (3H, s, H-20); 1.52-1.78 (3H, m, H-7α,β and H-11β); 1.80 (1H, ddd, J=3.0, 3.0, 9.9 Hz, H-6α); 2.12 (2H, m, H-3α and H-8); 2.20. (1H, s, H-10); 2.25-2.35 (2H, m, H-3β and H-6β); 2.51 (1H, dd, J=5.1, 13.2 Hz, H-11α); 2.68 (1H, sept, J=6.9 Hz, CH3CH(CH3)CO2); 2.77 (1H, dd, J=8.4, 8.4 Hz, H-4); 3.74 (3H, s, CO2CH3); 5.15 (1H, dd, J=9.9, 10.3 Hz, H-2); 5.52 (1H, dd, J=5.3, 11.9 Hz, H-12); 6.39 (1H, dd, J=0.9, 1.5 Hz, H-14); 7.40 (1H, dd, J=1.5, 1.5 Hz, H-15); 7.42 (1H, dd, J=0.9, 1.5 Hz, H-16).
