Acetate → Cholesta-5,7-dien-3beta-yl acetate

Participants

Reaction Steps

507.6 mg of the pure 7α-bromocholester acetate obtained sub (a) were dissolved in 5 ml of anhydrous tetrahydrofuran. To this solution was added at 25° C. a solution of 1.0 g of tetrabutyl ammonium fluoride which contained per mol 1 mol of crystal water, in 5 ml of anhydrous tetrahydrofuran, and then, after stirring at 20°-25° C. for 60 minutes, 10 ml of petroleum ether (40°-60° C.). The 1 mole crystal water-containing tetrabutyl ammonium fluoride was obtained by freeze-drying a 10% solution in water. After washing the reaction mixture three times with 10 ml of water, the organic layer was evaporated to dryness. 426 mg (100%) of dry substance were obtained with a content of 7-dehydrocholesterol acetate of 100% (UV). The final product could be recrystallized from ethanol in which 400 mg of white crystalline material were obtained with a melting-point of 128°-129° C. The crystalline final product was 100% pure Δ5,7-cholestadienol acetate both according to the UV-absorption spectrum and according to the NMR spectrum.

Provenance & Evidence