title: Synthesis of diastereomers of 3 alpha,7 alpha,12 alpha, 24-tetrahydroxy- and 3 alpha,7 alpha,24-trihydroxy-5 beta-cholestan- 26-oic acids and their structures.
abstract: Four stereoisomers of 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acids were synthesized as possible intermediates of the side-chain degradation step of bile acid biosynthesis. 3 alpha,7 alpha,12 alpha-Trihydroxy-5 beta-cholest-25-en-24-one prepared by thermolysis of beta-ketosulfoxide was reduced to the (24R)- and (24S)-allylic alcohols by reduction with sodium borohydride. Each isomeric alcohol was subjected to hydroboration and oxidation to give (25R)- and (25S)-3 alpha,7 alpha,12 alpha,24,26-pentahydroxy-5 beta-cholestanes. The separated four stereoisomers were converted into the corresponding 26-carboxylic acids. The stereoisomers of 3 alpha,7 alpha,24-trihydroxy-5 beta-cholestan-26-oic acids were synthesized in the same manner. To establish the stereochemistry of these carboxylic acids, the chemical transformation of methyl 3 alpha,7 alpha,12 alpha-trihydroxy- and 3 alpha,7 alpha-dihydroxy-5 beta-cholest-24-en-26-oates into the above stereoisomers and the reductive dehydroxylation of the 24-hydroxyl group into known 3 alpha,7 alpha,12 alpha,26-tetrahydroxy- and 3 alpha,7 alpha,26-trihydroxy-5 beta-cholestanes are described. The applications of spectroscopic methods (circular dichroism and 1H nuclear magnetic resonance) to elucidation of the stereochemistry are also discussed.
authors.affiliation: Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kurosawa
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Nakano
authors.forename: M
authors.initials: M
authors.lastname: Tohma
mesh_terms: D001647:Bile Acids and Salts / Q000096:biosynthesis / Q000138:chemical synthesis / Q000737:chemistry*; D002777:Cholestanols / Q000138:chemical synthesis / Q000737:chemistry*; D002942:Circular Dichroism; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
chemical_list: D001647:Bile Acids and Salts; D002777:Cholestanols; C024759:3,7,12,24-tetrahydroxycholestanoic acid; C022069:3,7,12-trihydroxycholestan-26-oic acid