An oxepane derivative of panaxadiol from the leaves of Panax notoginseng.

Hydrolysis of the crude saponin isolated from the leaves of PANAX NOTOGINSENG (Burk.) F. H. Chen yields five sapogenins which are separated by column chromatography. The structures of four of those were elucidated earlier to be panaxadiol, panaxatriol, dammar-20(22)en-3beta, 12beta,26-triol and 20(R)-dammaran-3beta, 12beta,20,25-tetrol. The fifth sapogenin is identified as an oxepane derivative probably arising from acid catalyzed dehydration and rearrangement of panaxadiol. The structure as proposed from NMR data was confirmed by single-crystal X-ray diffractometry.