Trimethylsulfonium iodide → (-)-(6aR,8R,9R,9aR)-9-Fluoro-2,2,4,4-tetraisopropyl-7-methylenehexahydrocyclopenta[f]-[1,3,5,2,4]trioxadisilocin-8-ol

Participants

Reaction Conditions

Reaction Steps

To a suspension of trimethylsulfonium iodide (30.5 g, 138.4 mmol) in THF (150 mL) at −20° C., n-BuLi (2.5 M solution in hexane) (55.3 mL, 138.4 mmol) was added. After 30 min, the epoxide 13 (6.0 g, 15.5 mmol) in THF (30 mL) was introduced at −20° C. and the reaction mixture allowed slowly to warm to 0° C. over 1 h. The mixture was then stirred at ambient temperature for 2 h, quenched with water and then extracted with ethyl acetate (3×200 ml). The combined organic layer was washed with brine, dried over Na2SO4 and concentrated reduced under pressure. The residues were purified on silica gel column chromatography (10% EtOAc/Hexane) to give the allylic alcohol 14 (5.1 g, 81%) as oil. [α]26D −0.54° (c 0.5, MeOH); 1H NMR (500 MHz, CDCl3) δ 0.93-1.12 (m, 28H), 1.99 (dd, J=2.5, 5.5 Hz, 1H, OH), 2.58 (m, 1H), 3.85 (dd, J=9.5, 11.5 Hz, 1H), 4.08 (dd, J=5.0, 12.0 Hz, 1H), 4.44 (m, 1H) 4.48 (m, 1H), 4.73 (dt, J=5.0, 9.0 Hz, 1H), 5.09 (s, 1H), 5.35-5.34 (m, 1H); 19F NMR (500 MHz, CDCl3) δ −203.0 (m); 13C NMR (125 MHz, CDCl3) δ 12.5, 12.9, 13.4, 13.5, 17.0, 17.03, 17.41, 17.46, 17.5, 17.6, 48.5, 50.2, 65.5, 72.6, 97.4 (d, J=185.0 Hz), 111.8, 146.8; HR-MS Calcd. For (C19H37FO4Si2+H)+ 405.2214. found 405.2202.

Provenance & Evidence