Steroids of Unnatural Configuration

Cholesterol has been converted into lOa-cholesterol by a method essentially identical with that used to prepare lOa-progesterone. Dehydration of (293) produced a mixture of A - and A -3-ketones in which the former predominated. Each could be converted to the same A -enol acetate which, on reduction with sodium borohydride, afforded lOa-cholesterol. 

9j8-Testosterone has been prepared by Simmons-Smith methylenation of the 5(10)-ene (294) followed by base-catalysed opening of the resulting cyclo- 

Syhora, J. A. Edwards, and A. D. Cross, Coll. Czech. Chem. Comm., 1969,34, 2459. 

Ozonolysis of neoergosterol under carefully defined conditions leads to high yields of aldehyde (297), which was further ozonised, as its morpholino-enamine, to the 19-norpregnane (298). A two-stage reduction using first ruthenium and then rhodium followed by Jones oxidation led to the cis-syn-cis-syn compound (299). 

The major products obtained by hydroxylation of 9j ,10a-retro-steroids with Curvularia lunata and brachyspora are 9 -equatorial alcohols, although 8j3-alcohols are also produced.  

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