
TY  - JOUR
A1  - Collins, DJ 
A1  - Hobbs, JJ 
T1  - Steroidal &#945;,&#946;-epoxyketones. IV. Synthesis of the isomeric 6&#946;-Bromo-4,5-epoxycholestan-3-ones
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1965
VL  - 18
IS  - 7
SP  - 1049
EP  - 1058
KW  - 
UR  - https://doi.org/10.1071/CH9651049 
N2  - 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%). 
ER  -

