Bismuth(III) Triflate-Catalyzed Direct Conversion of Corticosteroids into Highly Functionalized 17-Ketosteroids by Cleavage of the C17-Dihydroxyacetone Side Chain

The use of bismuth(III) triflate as catalyst for the direct conversion of corticosteroids into highly functionalized 17-ketosteroids by cleavage of the C17-dihydroxyacetone side chain is reported. This catalytic process is very chemoselective, since functionalities of the starting corticosteroids, such its Delta(4)-3-keto, Delta(1,4)-3-keto, 11 beta-hydroxyl, and 9 beta, 11 beta-epoxide, remained intact.