Schiglautone A, a New Tricyclic Triterpenoid with a Unique 6/7/9-Fused Skeleton from the Stems of Schisandra glaucescens

Schiglautone A (1), a unique 6/7/9-fused tricyclic carbon backbone triterpenoid, was isolated from the stems of Schisandra glaucescens. Its structure was determined on the basis of spectroscopic analysis and single-crystal X-ray crystallography. A hypothetical biosynthetic pathway of 1 was postulated.