The synthesis and in vitro activity of some δ(7,9(11))-lanostadienes

Abstract

The synthesis of Δ(7,9(911))-lanostadiene derivatives functionalized at C(32) starting from 3β-acetoxy-7α,32-epoxylanostan-11-one has been presented. The Δ(7,9(911)) moiety was efficiently introduced in three steps in 71% yield by the regioselective abstraction of allylic 8β hydrogen. The formyl group of the key intermediate, 3β-benzoyloxylanosta-7,9(11)-dien-32- al, has been stereoselectively alkylated into (32S) derivative, whereas its oxidation unexpectedly afforded 3β-benzoyloxy-7-oxolanost-8-ene-32,11α- lactone and not the corresponding acid. δ(7,9(911))-lanostadienes possessing HC(32)=O, C(32)=N, HC(32S)CH3OH, H2C(32)OH, as well as some 11-keto lanostenes, were tested in Vitro against several purified cholesterogenic enzymes showing moderate activity, with most the active aldehyde 16 having IC50 = 86 μm.