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A DCM (0.5 mL) solution of 9 (3.3 mg, 9.9 mmol, 1 equiv.) and cesium carbonate (17.5 mg, 50 mmol, 5 equiv.) was cooled to 0° C. open to the air in a 10-mL heart-shaped flask, and palladium(II) hydroxide on carbon (20 wt % Pd, 0.3 mg, 0.50 mmol, 0.05 equiv.) and tert-butyl hydroperoxide (70 wt % in H2O, 5 μL, 50 μmol, 5 equiv.) were added sequentially. The flask was capped with a rubber septum, an oxygen-filled balloon was attached, and the flask was purged with oxygen. The flask was then placed in a 4° C. refrigerator and stirred vigorously. After 19.5 h, the slurry was diluted with DCM, warmed to room temperature, and filtered through a short plug of SiO2, rinsing with DCM followed by EtOAc. The resulting solution was concentrated in vacuo. Flash column chromatography (2 mL SiO2 in pipette, 9:1 to 4:1 to 1:1 hexane:EtOAc) afforded 0.9 mg (2.6 mmol, 26% yield) of 10 as a colorless residue. TLC Rf 0.56 (1:1 hexane:EtOAc). 1H NMR (600 MHz; CDCl3): δ 5.98 (td, J=17.1, 7.9 Hz, 1H), 5.35 (s, 1H), 5.06-5.01 (m, 2H), 4.99 (t, J=7.1 Hz, 1H), 3.91 (d, J=5.5 Hz, 1H), 3.71 (s, 3H), 3.48 (s, 3H), 2.69 (s, 1H), 2.53 (dd, J=14.2, 6.7 Hz, 1H), 2.39 (dd, J=14.2, 7.9 Hz, 1H), 2.06 (d, J=13.1 Hz, 1H), 2.04-1.98 (m, 2H), 1.73-1.67 (m, 1H), 1.64 (s, 3H), 1.55 (s, 3H), 1.43-1.36 (m, 1H), 1.34-1.28 (m, 1H), 1.25 (s, 3H). 13C NMR (125 MHz; CDCl3): δ 197.8, 180.7, 136.8, 132.1, 124.2, 117.3, 115.2, 100.9, 80.9, 56.8, 56.5, 52.1, 48.3, 48.1, 38.2, 38.0, 34.1, 27.8, 25.8, 22.8, 17.8. HRMS-ESI (m/z): [M+Na]+ calculated for C21H30O4, 369.2036. found, 369.2034.

1. customThe flask was capped with a rubber septum
2. customthe flask was purged with oxygen
3. customwas then placed in a 4° C.
4. additionthe slurry was diluted with DCM
5. filtrationfiltered through a short plug of SiO2
6. washrinsing with DCM
7. concentrationThe resulting solution was concentrated in vacuo