Reaction Steps
A DCM (6 mL) solution of 8 (100 mg, 0.30 mmol, 1 equiv.) and 2,6-di-tert-butyl-4-methylpyridine (124 mg, 0.60 mmol, 2 equiv.) was cooled to −78° C. in a 20-mL scintillation vial, and trimethylsilyl trifluoromethanesulfonate (65 μL, 0.36 mmol, 1.2 equiv.) was added dropwise. Immediately upon this addition, the solution turned bright yellow. After stirring at −78° C. for 30 min, the reaction was quenched with saturated aqueous NaHCO3 and allowed to warm to room temperature. The mixture was then extracted four times with EtOAc. The organic extracts were combined, washed with brine, dried over Na2SO4, filtered, and concentrated in vacuo to a slight yellow oil. Flash column chromatography (50 mL SiO2, 99:1 hexane:EtOAc) afforded 85 mg (0.26 mmol, 85% yield) of 9 as a clear, colorless oil. TLC Rf 0.53 (9:1 hexane:EtOAc). 1H NMR (600 MHz; CDCl3): δ 6.02 (ddt, J=17.2, 10.1, 7.1 Hz, 1H), 5.04 (t, J=7.1 Hz, 1H), 5.01-4.95 (m, 2H), 4.54 (dd, J=5.7, 2.1 Hz, 1H), 3.75 (d, J=5.3 Hz, 1H), 3.48 (s, 3H), 3.47 (s, 3H), 2.42 (dd, J=14.1, 7.3 Hz, 1H), 2.29 (dd, J=14.1, 7.0 Hz, 1H), 2.19 (ddd, J=18.1, 6.7, 2.2 Hz, 1H), 2.07-2.02 (m, 2H), 2.01-1.93 (m, 1H), 1.86 (dd, J=12.4, 5.3 Hz, 1H), 1.81 (d, J=12.4 Hz, 1H), 1.72-1.65 (m, 4H), 1.58 (s, 2H), 1.47-1.42 (m, 1H), 1.25-1.20 (m, 1H), 1.14 (s, 3H). 13C NMR (125 MHz; CDCl3): δ 158.1, 138.3, 131.7, 124.9, 115.8, 112.5, 90.7, 79.1, 54.6, 51.3, 46.3, 44.4, 42.0, 38.87, 38.72, 33.6, 28.1, 25.9, 22.9, 20.1, 17.8. IR (NaCl, thin film, cm−1) 2966, 2930, 1671, 1578, 1460, 1439, 1376, 1304, 1215, 1168, 1136, 1062, 1001, 906. HRMS-ESI (m/z): [M+Na]+ calculated for C21H32O3, 355.2244. found, 355.2245.
