Preparation of radiolabelled 3α-hydroxy-7-keto-5β-cholanic acid and its glycine and taurine conjugates

Article abstract of DOI:10.1002/jlcr.2580160308

3α-Hydroxy-7-keto-5β-cholanic acid has been prepared from cholic acid by a route which allowed introduction of ³H into positions 11 and 12 of the steroid C ring. Labelling with ¹⁴C was done by halodecarboxylation and resynthesis of the carboxyl function with ¹⁴C cyanide. The conjugates of both ³H- and ¹⁴C-labelled compounds with glycine and taurine were prepared. ¹⁴C-labelled compounds were prepared by degradation of the carboxyl-containing side chain to the norchloride, which was used to prepare the homologous ¹⁴C-containing nitrile. Hydrolysis afforded the acid in good yield. ³H was introduced into the C ring of the steroid nucleus by dehydration of 3α,12α-dihydroxy-7-keto-5β-cholanic acid to the Δ¹¹-alkene which was catalytically tritiated. Physical and spectral data are presented to characterize the new compounds and TLC methods for purification are reported.