Reaction Steps
To a solution of 11 (622 mg, 1.28 mmol) in THF (25 mL) was added Bu4NF (12.5 mL, 1 M solution in THF), and the reaction mixture was stirred for 20 min. A mixture of Et3N (65 mg, 0.064 mmol) and HOAc (44 mg, 0.73 mmol) in THF (1.5 mL) was then added, and stirring was continued. The HOAc-Et3N addition was repeated after 2 h, and the reaction was stirred an additional 5 h, after which time the solvent was evaporated. The syrup obtained was then dissolved in EtOAc (30 mL) and washed with water (30 mL). The aqueous layer was separated and extracted with EtOAc (2×30 mL). The combined organic layers were dried (MgSO4) and concentrated. The residue obtained was purified by silica gel chromatography to give 2 (390 mg, 82%) as a white solid: mp 175°-176° C.; [α]D20 +44.0° (c 1.0, acetone); 1H NMR (CDCl3): δ 1.00 (t, 3H, J=7.30 Hz, --CH2CH3), 1.10 (d, 3H, J=6.9 Hz, --CH3), 1.40 (d, 3H, J=6.3 Hz, --CH3), 1.45, 1.47 (2s, 6H, --C(CH3)2), 1.62 (m, 2H, --CH2CH3), 1.71 (m, 1H, H-11), 2.86 (m, 2H, H-13), 2.91 (d, 1H, J=3.9 Hz, --OH), 4.24 (m, 1H, H-10), 4.94 (t, 1H, J=3.4 Hz, H-12), 5.50 (d, 1H, J=9.9 Hz, H-7), 5.90 (s, 1H, H-3), 6.61 (d, 1H, J=9.89 Hz, H-8); 13C NMR (CDCl3): δ 12.46, 13.94, 18.81, 23.20, 27.63, 27.81, 38.26, 38.51, 61.74, 72.94, 77.60, 103.47, 106.08, 106.39, 110.26, 116.55, 126.70, 151.33, 153.12, 153.90, 158.67, 160.95. Anal. Calcd for C22H26O5 : C, 71.33; H, 7.07. Found C, 71.18; H, 7.12.
