Stereoselective synthesis of 3β-bile acid derivatives from the 3α-analog

Article abstract of DOI:10.1016/0009-3084(95)02476-Y

The stereoselective transformation from the commonly occurring 3α-bile acids and derivatives to their 3β-analogs is important for certain applications of these amphiphilic natural compounds, especially in the preparation of polymers. We report here the stereoselective conversion of methyl cholate to its 3β-hydroxy epimer by the use of the Mitsunobu reaction and to a 3β-amino cholic acid analog via a tosylation followed by a S(n)2 displacement with sodium azide and a hydrogenation of the azide group with overall yields of 86% and 78%, respectively. The preparation of the methacrylate and methacrylamide derivatives from these compounds is also described.