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To a stirred solution of allylic alcohol 14 (5 g, 12.3 mmol) the Dess-martin periodinane reagent (7.8 g, 18.5 mmol) was added at 0° C. The mixture was warm to ambient temperature and stirred for 1 h. Mixture was passed through celite bed and the filtrate was concentrated under reduced pressure to give a crude allylic ketone, which was proceeded as such in next step without further purification. The crude ketone (4.5 g, 11.1 mmol) was dissolved in anhydrous methanol, cooled the solution at −78° C., CeCl3.7H2O (5.5 g, 14.7 mmol) was added at −78° C., and then after 10 minutes stirring, NaBH4 (0.54 g, 14.3 mmol) was added at one portion. After 15 min stirring at −78° C., the reaction mixture was allowed to reach 0° C., saturated solution of ammonium chloride (30 mL) and 10% aqueous solution of acetic acid were added, and then the mixture was allowed for 1 hr while stirring. Organic solvent was removed under reduced pressure and the residue was extracted with DCM (200 ml×2). The combined DCM extracts were washed with brine (50 mL×2), dried (anhydrous Na2SO4), filtered and concentrated under reduced pressure. The residue was purified by flash silica gel column chromatography (5% EtOAc/hexane) to give compound 15 (4.3 g, 86%) as oil. [α]26D −88.1° (c 0.5, MeOH); 1H NMR (500 MHz, CDCl3) δ 0.93-1.08 (m, 28H), 2.66 (s, 1H), 3.89 (dd, J=6.0, 11.5 Hz, 1H), 3.99 (dd, J=4.5, 12.0 Hz, 1H), 4.26-4.21 (m, 1H), 4.47 (dd, J=4.5, 13.5 Hz 1H), 4.65 (dt, J=8.0, 15.0 Hz, 1H), 5.16 (d, J=2.5 Hz, 1H), 5.35 (s, 1H); 19F NMR (500 MHz, CDCl3) δ −195.8 (m); 13C NMR (125 MHz, CDCl3) δ 12.5, 12.7, 13.3, 13.4, 16.9, 16.98, 17.07, 17.08, 17.4, 17.5, 49.1, 63.7, 73.7, 74.7, 102.3 (d, J=192.7 Hz), 111.5, 144.9, 150.0; HR-MS Calcd. For (C19H37FO4Si2+H)+ 405.2214. found 405.2202.

1. concentrationthe filtrate was concentrated under reduced pressure
2. customto give a crude allylic ketone, which
3. customwithout further purification
4. temperaturecooled the solution at −78° C.
5. stirringafter 10 minutes stirring
6. stirringAfter 15 min stirring at −78° C.
7. customto reach 0° C.
8. waitthe mixture was allowed for 1 hr
9. stirringwhile stirring
10. customOrganic solvent was removed under reduced pressure
11. extractionthe residue was extracted with DCM (200 ml×2)
12. washThe combined DCM extracts were washed with brine (50 mL×2)
13. dry with materialdried (anhydrous Na2SO4)
14. filtrationfiltered
15. concentrationconcentrated under reduced pressure
16. customThe residue was purified by flash silica gel column chromatography (5% EtOAc/hexane)