Kadcoccinones A–F, New Biogenetically Related Lanostane-Type Triterpenoids with Diverse Skeletons from Kadsura coccinea

Six new lanostane-related triterpenoids, kadcoccinones A–F (1–6), were isolated from Kadsura coccinea. Compound 3 possesses a novel 6/6/9-fused carbocyclic core containing a rare oxabicyclo[4.3.1]­decane system. Compounds 4 and 5 are isomers representing the first example of the 18(13 → 12)-abeo-26-norlanostane triterpenoid. The absolute configurations of 1 and 4–6 were defined by X-ray diffraction and experimental ECD spectra, and that of 3 was elucidated by quantum chemical calculations. The plausible biogenetic pathway of 1–6 is postulated.