p-Toluenesulfonic acid/methanol: mild reagent for the preparation of bile acid methyl esters.

Article abstract of DOI:10.1016/S0039-128X(81)80021-9

An improved method for the preparation of bile acid methyl esters is described. This is achieved by the addition of catalytic amounts of p-toluenesulfonic acid in a solution of bile acid in methanol. Advantages of this procedure over conventional methods include (1) use of a mild solid acid catalyst which prevents the formation of undesirable byproducts, (2) isolation of a solid product of high purity and (3) utilization of a relatively safe reagent in comparison to other methods involving diazomethane, hydrochloric acid or sulfuric acid.