Potassium Fluoride → ethyl (2E,4E)-5-(8-hydroxy-2,3,7,9,9-pentamethyl-1,4-dioxaspiro[4.5]dec-6-en-8-yl)-3-(trifluoromethyl)penta-2,4-dienoate

Participants

Reaction Steps

Under argon, 2,3,7,9,9-pentamethyl-8-[(E)-2-(tributylstannyl)vinyl]-1,4-dioxaspiro[4.5]dec-6-en-8-ol (300 mg, 0.55 mmol) and ethyl (2Z)-4,4,4-trifluoro-3-iodobut-2-enoate (163 mg, 0.55 mmol) in a round-bottom flask that had been dried by heating were dissolved in abs. N,N-dimethylformamide (4 ml), dichlorobis(acetonitrile)palladium(II) (7 mg, 0.03 mmol) was added and the mixture was stirred at room temperature for 3 h. After the addition of potassium fluoride solution, the reaction mixture was stirred further at room temperature overnight. The aqueous phase was then repeatedly extracted thoroughly with diethyl ether, and the combined organic phases were then dried over magnesium sulfate, filtered and concentrated under reduced pressure. By final column chromatography purification of the resulting crude product (ethyl acetate/heptane gradient), ethyl (2E,4E)-5-(8-hydroxy-2,3,7,9,9-pentamethyl-1,4-dioxaspiro[4.5]dec-6-en-8-yl)-3-(trifluoromethyl)penta-2,4-dienoate (150 mg, 61% of theory) was obtained in the form of a colorless oil. 1H-NMR (400 MHz, CDCl3 δ, ppm) 7.47 (d, 1H), 6.29 (d, 1H), 6.25 (s, 1H), 5.48 (s, 1H), 4.26 (q, 2H), 3.68 (m, 1H), 3.59 (m, 1H), 1.93 (d, 1H), 1.83 (br. m, 1H, OH), 1.77 (d, 1H), 1.69 (s, 3H), 1.32 (t, 3H), 1.25 (m, 3H), 1.18 (m, 3H), 1.10 (s, 3H), 0.91 (s, 3H).

Provenance & Evidence