Hyodeoxy cholic acid

The bile acid derivative, 3P-acetoxychol-5-en-24-oic acid (32), has been converted in two steps in high yield to 25-hydroxycholesterol (80). The homocholenic acid derivative (33) prepared by a photochemical Wolff rearrangement in this transformation served as a key early intermediate in the first chemical synthesis of la,25-dihydroxycholecalciferol (171). Lithocholic acid, likewise, has been converted to an intermediate (16) used for the preparation of the dihydroxyvitamin (35). Hyodeoxy-cholic acid (34) also shows promise of being a desirable starting material for 25-hydroxycholesterol (132). 

By 1900, only deoxycholic acid and cholic acid had been obtained in pure crystalline form. In 1911, Fischer (30) isolated lithocholic acid from a gallstone in the course of his classical studies on the bile pigments. Hyodeoxy-cholic acid was purified by Windaus and Bohne in 1923 (31) and chenodeoxy-cholic acid was rediscovered almost simultaneously by Wieland and Reverey (32) and by Windaus et al. (33) in 1924. 

Bile acids can also be converted into phenacyl [81] and p-bromophenacyl [102] esters. A bile acid sample with 50% excess of 0.15 M triethylamine in acetonitrile was warmed briefly and 0.1 M phenacyl bromide (50% molar excess) in acetonitrile was added. The reaction mixhire was maintained at 80—90°C for 45—60 min. The separation of phenacyl esters of lithocholic, deoxy-cholic, chenodeoxycholic, ursodeoxycholic hyodeoxy-cholic and cholic acids was carried out on an ODS column. The excess derivatizing agents and interfering biological compounds from bile samples were first eluted with n-heptane/dioxane (90 10 v/v), and the separation of derivatives of bile adds was accomplished with n-heptane/dioxane/isopropanol (70 25 5, by vol). The detection limits at 254 nm for the derivatives were 5-lOng [81]. 

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