
%0 Journal Article
%A Collins, DJ 
%A Hobbs, JJ 
%A Rawson, RJ 
%T 4,5-Seco-4,6-cyclosteroids. III. Observations on the course of reductive rearrangement of 6&#946;-Bromo-4&#946;,5-epoxy-5&#946;-cholestan-3&#946;-ol
%J Australian Journal of Chemistry
%D 1969/04/01
%V 22
%N 4
%P 807-819
%K 
%R https://doi.org/10.1071/CH9690807
%U https://www.publish.csiro.au/paper/CH9690807 
%X It has been shown that reductive rearrangement of 6&#946;-bromo-4&#946;,5-epoxy- 5&#946;-cholestan-3&#946;-ol (I) to 4,5-seco-4,6-cycle-6&#946;-cholestane-3&#946;,5&#945;-diol (IXa) with lithium aluminium hydride in tetrahydrofuran proceeds via 6&#946;-bromo-5&#946;-cholestane-3&#946;,5-diol (IIa). Relevant reactions of the latter and the corresponding 3-ketone are discussed.     Similar conversion of the 3-epimer of (I) into 4,5-seco-4,6-cyclo- 6&#946;-cholestane-3&#945;,5&#945;-diol (XIIIa) in high yield indicates that reductive rearrangement of the 6&#946;-bromo-5&#946;-hydroxy moiety proceeds without participation of the 3-aluminate complex. Some derivatives of (XIIIa) are described.     Experimental conditions required for the conversion of (I) into (IXa) are defined.     Combined evidence indicates that the reaction proceeds in a concerted manner by essentially base-catalysed, 1,3-elimination of hydrogen bromide from diol (IIa) with 4,5-bond migration to give the formal intermediate 3&#946;-hydroxy-4,5-seco-4,6-cyclo-6&#946;-cholestan-5-one (VI), further reduced to (IXa). 
