Reaction Steps
A 200-mL round-bottomed flask was charged with enone 10 (1.1 g, 2.2 mmol, 1.0 equiv) and MeOH:CH2Cl2 (7:1, 32 mL). The resulting solution was cooled to 0° C., and a cooled solution of H2O2 (30% aq., 20 mL) and NaOH (20% aq., 5 mL) was added dropwise. The reaction was stirred at 0° C. for 2 h, and diluted with Et2O (30 mL). The layers were separated and the aqueous layer was extracted with Et2O (3×15 mL). The combined organics were washed with H2O (3×30 mL), brine (20 mL), dried with magnesium sulfate, and concentrated in vacuo. The crude product was purified via flash chromatography (70:30 petroleum ether:acetone) affording the title compound as a clear, viscous oil with >20:1 diastereoselection (0.91 g, 81%). Analytical data: [α]D19 −22.4 (c=1.00, CHCl3); 1H NMR (600 MHz, CDCl3): δ 7.32-7.26 (m, 5H), 5.66 (d, J=9.6 Hz, 1H), 5.20 (d, J=12.0 Hz, 1H), 4.93 (d, J=12.6 Hz, 1H), 4.68 (s, 1H), 4.68-4.66 (m, 1H), 4.07-4.04 (m, 2H), 4.02-3.98 (m, 2H), 2.64 (s, 6H), 1.15 (d, J=6.6 Hz, 3H), 0.89 (s, 9H), 0.11 (s, 3H), 0.10 (s, 3H); 13C NMR (150 MHz, CDCl3): δ 204.4, 156.9, 156.0, 136.6, 128.3, 128.1, 128.0, 74.0, 69.3, 66.4, 65.9, 60.7, 56.0, 52.3, 36.1, 25.5, 18.2, 17.7, −3.9, −4.8; LRMS (ESI+) Calcd. for C25H39N3O7Si+, 522.26. Found, 522.23. IR (thin film, cm−1) 3402, 2954, 2857, 2359, 2249, 2125, 1650, 1519, 1227, 830, 732; TLC (70:30 petroleum ether/acetone): Rf=0.30.
