Reaction Steps
To a solution of 9 (1.44 g, 3.89 mmol) in dry CH2Cl2 (50 mL) at -20° C. was added pyridine (6 mL), DMAP (1.10 g, 9.00 mmol) and tert-butylchlorodimethylsilane (1.40 g, 9.28 mmol). The reaction mixture was stirred under nitrogen at room temperature for 1.5 h until disappearance of the starting material was observed. Water (15 mL) was then added, and the mixture was stirred for an additional 15 min. The organic layer was separated, and the aqueous layer was extracted with CH2Cl2 (2×15 mL). The combined organic layers were evaporated under reduced pressure at room temperature. The oil obtained was submitted to silica gel chromatography (solvent B) to obtain 10 (1.80 g, 95%) as a syrup: [α]D20 +26° (c 3.8, acetone); 1H NMR (CDCl3): δ -0.11, 0.08 (2s, 6H, --SiCH3), 0.80 [s, 9H, --C(CH3)3 ], 0.90 (d, 3H, J=6.90 Hz, --CHCH3), 0.96 (t, 3H, J=7.30 Hz, --CH2CH3), 1.39, 1.43 (2s, 6H, --C(CH3)2), 1.60 (m, 2H, --CH2CH3), 2.54 (m, 1H, --CHCH3), 2.80 (m, 2H, --CH2CH2CH3), 4.86-5.00 (m, 2H, --CH=CH2), 5.22 [d, 1H, J=6.85 Hz, --CHOSi(CH3)2 --], 5.46 (d, 1H, J=10.0 Hz, H-3), 5.68-5.87 (m, 1H, --CH=CH2), 5.83 (s, 1H, H-9), 6.59 (d, 1H, J=10.0 Hz, H-4), 9.20 (s, 1H, Ar--OH); 13C NMR (CDCl3): δ -0.42, -0.22, 13.90, 16.14, 17.95, 23.02, 25.58, 27.47, 27.90, 38.49, 44.45, 74.08, 77.49, 102.63, 106.65, 106.72, 110.00, 115.60, 116.51, 126.61, 139.63, 150.99, 151.69, 155.33, 158.33, 160.90; Anal. Calcd for C28H40O5Si: C, 69.38; H, 8.32. Found C, 68.55; H, 8.42. MS (negative-ion FAB): m/z 483 (M-1)-, 351, 297.
