A Simple and Mild Procedure for the Preparation of Bile Acid Methyl Esters

Abstract

Bile acid ester are useful intermediates in reaction schemes yielding bile alcohols^2–5 and other acid derivatives. Reported methods for the preparation of bi le acid methyl or ethyl esters consist of dissolving the bile acid in a large excess of absolute alcohol (ei ther methanol or ethanol) containing a catalytic amount of concentrated mineral acid (either hydrochloric or sul furic). Alternately bile acid methyl esters have been prepared using diazomethane thus avoid the use of strong mineral acids. This very simple methods, presented howe ver several drawbacks. In the former method, the use of strong mineral acids, expecially hydrochloric acid, on polyhydroxy steroids, such as bile acids, can often cau se the formation of undesirable side products.