Involucratusins A–H: Unusual Cadinane Dimers from Stahlianthus involucratus with Multidrug Resistance Reversal Activity

Three novel cadinane dimers, involucratusins A-C (1-3), five unique nor-cadinane-dimers, involucratusins D-H (4-8), together with a known compound (9) were isolated from the rhizomes of Stahlianthus involucratus. Their challenging structures and absolute configurations were determined by spectroscopic data, CD experimentation, chemical conversions and single-crystal X-ray diffraction. Compounds 1-3 are unusual cadinane dimers with new connection...