Ten undescribed cadinane-type sesquiterpenoids from Eupatorium chinense.

Ten undescribed cadinane-type sesquiterpenes (1 − 10) were isolated from the whole plant of Eupatorium chinense. Their planar structures were mainly elucidated by extensive analysis of spectroscopic data and DFT NMR calculations. The absolute configurations of 1 , 2 , and 3 were determined by TDDFT ECD calculations while those of compounds 4 – 7 and 9 were confirmed by single crystal X-ray diffraction experiments. Compounds 2 and 3 are a pair of C-10 epimers, compounds 4 and 5 a pair of C-1 epimers, and compounds 9 and 10 a pair of compounds isomerized at both C-1 and C-10. A possible biosynthetic pathway for these new sesquiterpenes was proposed. [Display omitted] [ABSTRACT FROM AUTHOR]