Synthesis of 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oic acids by the use of beta-ketosulfoxide.

The biosynthetic intermediates of bile acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oic acids, were synthesized by means of the thermal elimination of beta-ketosulfoxides. The alpha, beta-unsaturated ketones as key compounds of the synthesis, 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholest-25-en-24-ones, were effectively derived from the beta-ketosulfoxides prepared from methyl cholate or chenodeoxycholate by reaction with methylsulfinylcarbanion. These unsaturated ketones were converted into 3 alpha, 7 alpha, 12 alpha, 26-tetrahydroxy- and 3 alpha, 7 alpha, 26-trihydroxy-5 beta-cholestanes by reductive deoxygenation and hydroboration, of which stereoisomers were chromatographically separated into 25S- and 25R- isomers. The oxidation of each of the above isomeric alcohols after the protection of the hydroxyl groups on the steroidal ring and the following hydrolysis gave the title 26-carboxylic acids.