Yoshii M, Une M, Kihira K, Kuramoto T, Hoshita T
Chem Pharm Bull (Tokyo). 1989 Jul;37(7):1852-4. doi: 10.1248/cpb.37.1852.
In order to confirm the structure of alpha-trichechol, the major bile alcohol of the West Indian manatee, chemical synthesis of 5 beta-cholestane-3 alpha,6 beta,7 alpha,25,26-pentol was carried out. The chain of 3 alpha-hydroxy-5 beta-chol-6-en-24-oic acid was elongated by an Arndt-Eistert reaction to form 3 alpha-hydroxy-26,27-dinor-5 beta-cholest-6-en-25-oic acid. The unsaturated C25 bile acid was converted into 3 alpha,6 beta,7 alpha-trihydroxy-25-homo-5 beta-cholan-25-oic acid by 1,2-glycol formation of the delta 6-double bond. The acetylated derivative of the trihydroxy C25 bile acid was then converted into 3 alpha,6 beta,7 alpha,26-tetraacetoxy-27-nor-5 beta-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, 5 beta-cholestane-3 alpha,6 beta,7 alpha,25,26-pentol. By direct comparison with the synthetic pentahydroxy bile alcohol, the structure of the naturally occurring alpha-trichechol was determined to be 5 beta-cholestane-3 alpha,6 beta,7 alpha,25,26-pentol.
为了确定西印度海牛的主要胆汁醇α-三胆醇的结构，进行了5β-胆甾烷-3α,6β,7α,25,26-戊醇的化学合成。通过阿恩特-艾斯特尔特反应延长3α-羟基-5β-胆甾-6-烯-24-酸的碳链，以形成3α-羟基-26,27-二降-5β-胆甾-6-烯-25-酸。通过δ6-双键的1,2-二醇形成，将不饱和的C25胆汁酸转化为3α,6β,7α-三羟基-25-高-5β-胆烷-25-酸。然后，通过先后用亚硫酰氯、重氮甲烷和乙酸处理，将三羟基C25胆汁酸的乙酰化衍生物转化为3α,6β,7α,26-四乙酰氧基-27-降-5β-胆甾烷-25-酮。25-氧代化合物与甲基碘化镁的格氏反应得到所需的胆汁醇，即5β-胆甾烷-3α,6β,7α,25,26-戊醇。通过与合成的五羟基胆汁醇直接比较，确定天然存在的α-三胆醇的结构为5β-胆甾烷-3α,6β,7α,25,26-戊醇。
