Nardoaristolones A and B, Two Terpenoids with Unusual Skeletons from Nardostachys chinensis Batal

Nardoaristolones A and B, two novel terpenoids derived from the aristolane-type sesquiterpenoid, were isolated from the underground parts of Nardostachys chinensis Batal. Nardoaristolone A is the first reported aristolane-chalcone derivative, while nardoaristolone B possesses a nor-aristolane sesquiterpenoid skeleton with an unusual 3/5/6 tricyclic ring system. Their structures were elucidated by spectroscopic measurements, and the absolute configurations were established by single-crystal X-ray diffraction experiments.