Iodine → 7alpha-(5-Chloropentyl)-11beta-fluor-estr-4-ene-3,17-dione

Participants

Reaction Conditions

Reaction Steps

First, 20% of a solution of 39 ml of 1-bromo-5-chloropentane in 300 ml of THF is added to a suspension of 7.2 g of magnesium chips in 100 ml of THF under nitrogen. After the reaction starts, which can be achieved by adding iodine and dibromomethane, the remaining solution is added in drops in such a way that the internal temperature does not exceed 35° C. In a second flask, 51.2 g of lithium bromide is added to a suspension of 28.1 g of copper(I) iodide in 130 ml of THF at 0° C., whereby the internal temperature climbs to 40° C. Without cooling, 49.4 ml of 1,3-dimethyl-3,4,5,6-tetrahydro-(1H)-pyrimidin-2-one is now added and stirred for 15 minutes at 40° C. A clear solution is obtained, which is added in drops to the Grignard solution that is cooled to −50° C. Then, it is stirred for 15 more minutes at −30° C. and mixed at −70° C. drop by drop with a solution of 25 g of 11β-fluoro-estra-4,6-diene-3,17-dione in 260 ml of THF, 26 ml of 1,3-dimethyl-3,4,5,6-tetrahydro-(1H)-pyrimidin-2-one and 59 ml of trimethylchiorosilane in such a way that the internal temperature does not exceed −65° C. It is stirred for 30 minutes cold, then 34.7 ml of glacial acetic acid is added in drops, the cooling bath is removed, and it is stirred for 1 more hour at room temperature. For working-up, the reaction mixture is added to 1.5 1 of water, diluted with the same amount of ethyl acetate, the precipitate is separated on Celite, rewashed with ethyl acetate, the aqueous phase is extracted 3 times with ethyl acetate, washed with sodium bicarbonate and common salt solution, dried on magnesium sulfate and concentrated by evaporation in a vacuum. After the crude product is chromatographed on silica gel with a hexane-ethyl acetate gradient, 22.1 g of 7α-(5-chloropentyl)-11β-fluoro-estr-4-ene-3,17-dione is obtained.

Provenance & Evidence