A concise synthesis of ent-cholesterol

ent-Cholesterol was synthesized in 16 steps,from commercially available (S)-citronellol. The overall yield for the synthesis was 2.0%. This route is amenable to gram-scale preparation of ent-cholesterol. Isotopic incorporation near the end of the synthesis was achieved using labeled methyl iodide. This synthesis is the most practical to date and will make ent-cholesterol more readily available to use as a probe of the function and metabolism of cholesterol.