Bisnorsesquiterpenoids from Euphorbia resinifera Berg. and an expeditious procedure to obtain resiniferatoxin from its fresh latex

The fresh latex of cultivated E. resinifera Berg. is a convenient source of the ultrapotent vanilloid resiniferatoxin, and a transesterification-reesterification procedure that substantially alleviates the hazards associated with the direct isolation of this obnoxious diterpenoid has been developed. Various known phorboid constituents of the diterpenoid fraction were obtained in pure form and have been spectroscopically characterized for the first time, while the non-diterpenoid fraction of the latex gave, besides some common triterpenoids, three new bisnorsesquiterpenes of the dihydroionol type. The structures of these compounds were established through a combination of spectroscopic data and chemical reactions.