Microwave-induced organic reactions of bile acids: esterification, deformylation and deacetylation using mild reagents.

An efficient and convenient procedure for the esterification, deformylation, and deacetylation of bile acids is described. This is achieved by the addition of a catalytic amount of methanesulfonic acid or para-toluene sulfonic acid to a solution of bile acid in methanol in the domestic microwave oven. All these reactions were completed in the microwave oven within 1-3 min at 60% power (390 W) and the desired bile acids, namely trihydroxy-5 beta-cholestanoic acid, (23R)-3 alpha,7 alpha,23-trihydroxy-5 beta-cholan-24-oic acid, ursocholic acid and 7-ketolithocholic acid were isolated in 86-94% yield.