Acetic Acid → 7alpha-[11-(Dimethyl-tert-butyl-silyloxy)undecyl]-4-estrene-3,17-dione

Participants

Reaction Steps

7.4 g of magnesium filings is placed into 31 ml of tetrahydrofuran and combined within 1.5 hours with a solution of 113 g of 11-bromoundecyl-tert-butyldimethylsilyl ether in 310 ml of tetrahydrofuran. After one hour at a bath temperature of 100°, the mixture is diluted with 157 ml of tetrahydrofuran, cooled to -30°, mixed with 29.5 g of copper(I) iodide, stirred for 0.2 hour at -30°, a solution of 25 g of 4,6-estradiene-3,17-dione [Kalvoda, J., and Anner, G., Helv. Chim. Acta 50 : 269 (1967)]in 220 ml of tetrahdyrofuran is added dropwise, and the mixture is further stirred for 1.5 hours at -30°. Then, 18.7 ml of glacial acetic acid is added, the mixture is concentrated under vacuum, poured on water, suctioned off through "Celite", rinsed with ethyl acetate, extracted twice with ethyl acetate, washed with water and sodium chloride solution, dried over sodium sulfate, concentrated to dryness under vacuum, and chromatographed on silica gel with hexane/ethyl acetate, thus obtaining 88.6 g of 7α-[11-(dimethyl-tert-butyl-silyloxy)undecyl]-4-estrene-3,17-dione, [α]D =54.4°, as an oil, as well as 55.2 g of 7β-[11-(dimethyl-tert-butylsilyloxy)undecyl]-4-estrene-3,17-dione, mp 65°.

Provenance & Evidence