
%0 Journal Article
%A Collins, DJ 
%A Hobbs, JJ 
%T Steroidal &#945;,&#946;-epoxyketones. IV. Synthesis of the isomeric 6&#946;-Bromo-4,5-epoxycholestan-3-ones
%J Australian Journal of Chemistry
%D 1965/07/01
%V 18
%N 7
%P 1049-1058
%K 
%R https://doi.org/10.1071/CH9651049
%U https://www.publish.csiro.au/paper/CH9651049 
%X 6&#946;-Bromocholest-4-en-3-one (I) was converted to 6&#946;-bromo-4&#945;,5-epoxy-5&#945;-cholestan-3-one (II) with alkaline hydrogen peroxide. 5,6&#946;-Dibromo-5&#945;-cholestane- 3&#946;,4&#946;-diol (X) with alkali gave 6&#946;-bromo-4&#946;,5-epoxy-5&#946;-cholestan-3&#946;-ol (IXa), which was oxidized to non-crystalline 6&#946;-bromo-4&#946;,5-epoxy-5&#946;-cholestan-3-one (XIII), characterized as the crystalline 3,3-dimethyl ketal (XIIa). Cleavage of (II) with hydrogen bromide in acetic acid gave 4,6&#946;-dibromocholest-4-en-3-one (V) via the isomeric bromohydrins (IVa) and (IVb). Compound (XIII) yielded (V) directly.   Sodium borohydride reduction of (I) gave cholesterol in high yield, while reduction with lithium tri-t-butoxyaluminium hydride afforded cholest-4-en-3-one (52%), cholesterol (30%), and cholest-4-en-6&#946;-ol-3-one (7%). 
