5«-Cholestan-2/3,3/3-thiirane

The use of thiocyanic acid for thiirane synthesis is usually compatible with many functional groups found in natural steroids. The method has found application in androstanes, pregnanes, cholestanes, cholanates and cardeno-lides. However, the presence of a,j5-unsaturated carbonyl groups may decrease the yield of the thiocyanatohydrin due to conjugate addition of thiocyanic acid. Indeed, the 1,4-addition of thiocyanic acid has been carried... 

Treatment of 2a.,3a.-Epoxy-5a-cholestane with Potassium Thiocyanayte to Yield the 2 3 -Thiirane ... 

To a mixture of ethyl 5a-cholestan-3-one 2a-xanthate (2 g, 3.95 mmol) and 100 ml methanol is added sufficient ether to completely dissolve the solids. Sodium borohydride (90 mg, 2.36 mmol) is added directly to the reaction flask and the solution is stirred at room temperature for 4 hr. (The use of an excess of sodium borohydride and an extended reaction time produces 5oc-cholestan-2a,3a-thiirane.) The reaction is diluted with 200 ml ether and washed several times with ca. 100 ml water, dried (MgS04) and the solvent is removed under vacuum. The crude sticky gum is chromatographed on a column of 85 g silicic acid. The hexane eluates contain 5a-cholest-2-ene. Ethyl 5a-cholestan-3a-ol 2a-xanthate is obtained in ca. 30% yield by subsequent elution with benzene hexane (1 7) and the desired ethyl 5a-cholestan-3 -ol 2a-xanthate is eluted with ether hexane (1 3) in ca. 30% yield. 

Cholestane-3/3,5a-diol 3-acetate, 397 Cholestane-4a,5a-diol 4-tosylate, 398 Cholestane-5a,6a-diol 6-tosylate,394 5a-Cholestan-2-one, 57, 88, 427 10(5 4 H)ijAeo-Cholestan-5-one, 398 10(5 6)ij ieo-Cholestan-5-one, 392, 394 5a-Cholestan-3-one cyanohydrin, 359 5a-Cholestan-3-one cyanohydrin acetate, 360 5a-Cholestan-2a,3a-oxide, 42 5a-Cholestan-2/3,3/3-thiirane, 43 Cholest-5-ene-3, 19-diol, 268 Cholest-5-ene-3, 25-diol, 71 5(10->l/3H)flfc eo-cholest- 10(19)-ene-3/8,5a-diol 3-acetate, 397, 398 Cholest-4-ene-3,6-dione, 105 Cholest-4-en-3-one, 318 Chromium trioxide, 147, 150 5a-Conanine-3/3-ol-ll-one 3-acetate, 259 Cupric bromide, 210, 211 Cuprous chloride-catalyzed conjugate addition, 76, 80... 

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