Biomimetic syntheses of kadcoccitane H and kadcotrione C methyl ester

Abstract

Kadcotriones and kadcoccitanes, renowned for their intricate 6/6/5-tricyclic and 6/6/5/6-tetracyclic ring systems, respectively, exhibit promising biological activities. This work proposes a biosynthetic pathway that elucidates how nature synthesizes these triterpenoids from lanosterol. Inspired by this pathway, we present the first biomimetic syntheses of kadcoccitane H and kadcotrione C methyl ester. These syntheses showcase key transformations including olefin transposition, a biomimetic ring contraction/expansion, SeO2 mediated one-pot allylic oxidation/isomerization-elimination/allylic oxidation cascade, regioselective dihydroxylation of sterically hindered double bond, unusual POCl3 mediated cleavage of diol and Still-Gennari olefination.