Bismuth(III) Triflate-Catalyzed Direct Conversion of Corticosteroids into Highly Functionalized 17-Ketosteroids by Cleavage of the <i>C</i>17-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 as Δ4-3-keto, Δ1,4-3-keto, 11β-hydroxyl, and 9β,11β-epoxide, remained intact.