The constituents of Olearia heterocarpa. The structure of olearin, a diterpene dilactone of the cascarillin group

Abstract

Chloroform extraction of Olearia heterocarpa S. T. Blake has yielded a new diterpene dilactone, olearin, the known flavone, xanthomicrol, an unknown C27H42O3 hydroxy acid, and a mixture of long-chain (approx. C50) esters. On chemical and spectroscopic evidence olearin (1) has been shown to possess a rearranged enantio-labdane skeleton of the type displayed by the cascarillins. Correlation of olearin with a diterpene of known stereochemistry has defined the absolute con- figuration at all but one centre.