Reaction Steps
To a solution of 6a (130 mg, 0.29 mmol) in THF (5 mL) was added Bu4NF (1.45 mL, 1M solution in THF) at 0° C. The reaction mixture was stirred at room temperature for 6 h. Water was added (2 mL), followed by brine (2 mL). The solution was extracted with ether (3×5 mL). The combined organic layers were dried (MgSO4), concentrated, and submitted for silica gel chromatography (Solvent B) to obtain 7a (92 mg, 91%) as a syrup: [α]D20 +26.5° (c 1.1, CHCl3); 1H NMR (CDCl3): δ 0.97 (t, 3 H, J=7.3 Hz, --CH2 CH2CH3), 1.08 (d, 3 H, J=7.0 Hz, --CHCH3), 1.37 [d, 9 H, J=6.2 Hz, --CH(CH3)2, CHCH3 ], 1.57 (m, 2 H, --CH2 CH2CH3), 1.70 (m, 1 H, H-9), 2.99 (m, 2 H, --CH2CH2 CH3), 4.22 (m,1 H, H-8), 4.59 [m, 1 H, --CH(CH3)2 ], 4.91 (d, 1 H, J=2.7 Hz, H-10), 5.88 (s, 1 H, H-3), 6.16 (s, 1 H, H-6): 13 C NMR (CDCl3): δ 12.49, 13.84, 18.83, 21.69, 21.74, 23.15, 38.38, 38.89, 61.65, 70.65, 72.87, 96.65, 104.20, 106.18, 110.10, 155.12, 156.36, 158.03, 159.09, 161.07. Anal. Calcd for C20H26O5 : C, 69.34; H, 7.56. Found: C, 69.15; H, 7.93.
