Synthesis of potential C 27-intermediates in bile acid biosynthesis and their deuterium-labeled analogs

Abstract

In connection with studies of alternative pathways in bile acid biosynthesis, potential intermediates in a pathway starting with 27-hydroxylation of cholesterol have been prepared in natural and deuterated forms. Established methods were used to prepare 27-hydroxycholesterol and 3β-hydroxy-5-cholestenoic acid. Clemmensen reduction of kryptogenin in unlabeled and deuterated solvents yielded 27-hydroxy-cholesterol and 16-oxo-5-cholestene-3β,27-diol, which were separated by adsorption chromatography on Unisil. The labeled 27-hydroxycholesterol and 3β-hydroxy-5-cholestenoic acid derived from it consisted of molecules with seven (50%), six (20%), and eight (20%) deuterium atoms, and unlabeled molecules were not detected. The acetates of 27-hydroxycholesterol and methyl 3β-hydroxy-5-cholestenoate were 7α-hydroxylated in a copper-catalyzed reaction with ert-butylperbenzoate, and the products were purified by chromatography on Unisil. The 7β-epimers were obtained as side products. Labeled 3β, 7α-dihydroxy-5-cholenic acid was prepared in the same way from 3β-hydroxy-5-[2,2,4,4,23- 2H 5]-cholenoic acid. The 3-oxo- Δ 4 analogs of the 3 β-hydroxy- Δ 5 compounds were prepared by oxidation with cholesterol oxidase. The labeled products had the same isotopic composition as the starting materials. Gas chromatographic retention indices and mass spectral characteristics of the trimethylsilyl ether derivatives of the neutral steroids and the methylated acids are given for all compounds. (Steroids 58:119–125, 1993)