An efficient total synthesis of the enantiomer of cholesterol is reported. The enantiomer of testosterone was prepared and converted into a C21l 3-silyloxy-Δ(5,17(20))-diene according to literature procedures. The additional five carbon atoms of the cholesterol side chain were introduced by an ene reaction. Selective hydrogenation of the resultant Δ16 double bond and removal of the 22-hydroxyl group by a mesylation and demesylation sequence gave ent-cholesterol in 9.7% overall yield from ent- testosterone.
- Ene reactions
- Steroids and Sterols