Transformed steroids 194. Synthesis of pregna-Δ4,9-dien-3,20-diones from their 9α-hydroxyanalogs
The approaches to the synthesis of various 16α,17α-disubstituted pregna-4,9-dien-3,20-diones from the corresponding 9α-derivatives with labile epoxide, dioxolane, and oxathiolane rings D' have been studied.The transformation has been found to proceed efficiently when the 9α-sulfinic esters are used at the intermediate stage and then elimination of sulfinic acid by TsOH/SiO2 is carried out.
Turuta, A. M.,Dzhlantiashvili, N. V.,Voishvillo, N. E.