Saturated B-homo ketones and hydrocarbons

Saturated B-Homo Ketones and Hydrocarbons 1. Tiffeneau Ring Enlargement 

B-Homosteroids were first reported by Ringold in the course of an investigation of the relationship of structural changes to biological activity of anabolic agents. The Tiffeneau rearrangement sequence described earlier for the preparation of A-homosteroids was used to synthesize 17/ -hydroxy-B-homo-5a-androstan-3-one (56a). 

In a study of the stereochemistry of the B-homosteroid ring system, Kohout, Fajkos and Sorm prepared 3 -hydroxy-B-homo-5a-cholestan-7-one acetate 

Tiffeneau ring enlargement of 5a-deuterio ketone (59) gives the required 3yS-hydroxy-B-homo-5a-deuteriocholestan-7-one acetate (60). The 6a-bromo-3 -hydroxy-B-homo-5a-deuteriocholestan-7-one acetate (61) obtained by bromination is then treated with lithium bromide in dimethylformamide to give the deuterium free a,j5-unsaturated ketone (62). The loss of deuterium bromide proves that bromination takes place at C-6 and that the carbonyl group must therefore be located at C-7. 

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