Abstract
In order to confirm the structure of α-trichechol, the major bile alcohol of the West Indian manatee, chemical synthesis of 5β-cholestane-3α, 6β, 7α, 25, 26-pentol was carried out. The chain of 3α-hydroxy-5β-chol-6-en-24-oic acid was elongated by an Arndt-Eistert reaction to form 3α-hydroxy-26, 27-dinor-5β-cholest-6-en-25-oic acid. The unsaturated C25 bile acid was converted into 3α, 6β, 7α-trihydroxy-25-homo-5β-cholan-25-oic acid by 1, 2-glycol formation of the Δ6-double bond. The acetylated derivative of the trihydroxy C25 bile acid was then converted into 3α, 6β, 7α, 26-tetraacetoxy-27-nor-5β-cholestan-25-one by successive treatment with thionyl chloride, diazomethane, and acetic acid. A Grignard reaction of the 25-oxo compound with methylmagnesium iodide afforded the desired bile alcohol, 5β-cholestane-3α, 6β, 7α, 25, 26-pentol. By direct comparison with the synthetic pentahydroxy bile alcohol, the structure of the naturally occurring α-trichechol was determined to be 5β-cholestane-3α, 6β, 7α, 25, 26-pentol.
