Novel polycyclic polyprenylated acylphloroglucinols from Hypericum sampsonii

Four new polycyclic polyprenylated acylphloroglucinols with a tricyclo[4.3.1.15,7]undecane skeleton, hypersampsones N-Q (1-4), together with four know compounds (5-8), were isolated from the aerial parts of Hypericum sampsonii. Compound 1 bearing a rare 20, 25-epoxy group with the losing of C-21-23 in isopentenyl. An unusual 21, 24-epoxy group was found in the structure of 2. All structures were elucidated by extensive NMR spectroscopic methods. The absolute configurations of new compounds were determined by ECD calculation.