The chemical synthesis of the 9α-hydroxy derivatives of chenodeoxycholic and lithocholic acids is reported. For initiating the synthesis of the 9α-hydroxy derivative of chenodeoxycholic acid, cholic acid was used; for the synthesis of the 9α-hydroxy derivative of lithocholic acid, deoxycholic acid was used. The principal reactions involved were (1) decarbonylation of conjugated 12-oxo-Δ 9(11) -derivatives using in situ generated monochloroalane (AlH 2 Cl) prepared from LiAlH 4 and AlCl 3 , (2) epoxidation of the deoxygenated Δ 9(11) -enes using m-chloroperbenzoic acid catalyzed by 4,4′-thiobis-(6-tert-butyl-3-methylphenol), (3) subsequent Markovnikov 9α-hydroxylation of the Δ 9(11) -enes with AlH 2 Cl, and (4) selective oxidation of the primary hydroxyl group at C-24 in the resulting 3α,9α,24-triol and 3α,7α,9α,24-tetrol to the corresponding C-24 carboxylic acids using sodium chlorite (NaClO 2 ) in the presence of a catalytic amount of 2,2,6,6-tetramethylpiperidine 1-oxyl free radical (TEMPO) and sodium hypochlorite (NaOCl). The 1 H-and 13 C-NMR spectra are reported. The 3α,7α,9α-trihydroxy-5β-cholan-24-oic acid has been reported to be present in the bile of the Asian bear, and its 7-deoxy derivative is likely to be a bacterial metabolite. These bile acids are now available as authentic reference standards, permitting their identification in vertebrate bile acids.

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