Reaction Steps
A mixture of dienyl sulfone 33 (45 mg, 0.11 mmol), OsO4 (2 mg, 0.0078 mmol), 4-methylmorpholine N-oxide (27 mg, 0.23 mmol) in acetone (0.5 mL) and H2O (0.5 mL) as co-solvent was stirred at room temperature for 36 h, then saturated aqueous Na2S2O3 (5 mL) was added, and stirred for 30 min. The reaction mixture was diluted with ethyl acetate (10 mL), separated, and the aqueous layer was extracted with ethyl acetate (3×5 mL). The combined organic layers were dried over Na2SO4 and concentrated. The residue was purified by flash column chromatography (ethyl acetate/hexanes; 1:1) to afford 40 mg (83%) of diol 39 as a colorless solid. mp 117.0-119.0° C.; [α]20D=−72.7 (c=1.09, CH2Cl2); 1H NMR (CDCl3, 300 MHz) δ 7.86-7.90 (m, 2H), 7.52-7.67 (m, 3H), 7.31 (d, J=7.5 Hz, 1H), 4.55 (d, J=2.7 Hz, 1H), 3.79 (dd, J=5.4 Hz, 1.5 Hz, 1H), 3.47 (dd, J=9.9 Hz, 2.4 Hz, 1H), 2.82 (m, 2H), 2.35 (m, 1H), 2.06 (br s, 1H), 1.26 (d J=7.5 Hz, 3H), 1.13 (d, J=6.9 Hz, 3H), 0.88 (s, 9H), 0.10 (s, 3H), 0.08 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ 147.9, 140.1, 138.9, 133.4, 129.2, 127.7, 77.5, 71.8, 69.8, 40.1, 35.9, 25.8, 18.0, 17.4, 16.8, −4.5, −4.8; Analytical. Calculated for C21H34O5SSi: C, 59.12; H, 8.03. Found: C, 59.07; H, 7.89.
