Abstract
Three new compounds, 7α, 12β-, 7β, 12α-, and 7β, 12β-dihydroxy-5α-cholanic acids, were synthesized. The principal reactions employed were 1) selective acylation at C-7 of a 7α, 12α-dihydroxy ester with the propionic anhydride-4-dimethylaminopyridine system, 2) potassium superoxide-18-crown-6 ether inversion of the 7α-hydroxyl group, and 3) stereoselective reduction of the 12-ketones with the sodium borohydride-palladium chloride system and tert-butylamineborane complex. High-performance liquid chromatography was of key importance in characterizing the compounds and determining their purity
