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 oxabicydo [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.