Steam distillation of the leaf and terminal branchlets of Prostanthera
sp. aff. ovalifolia growing in northeastern New South Wales give 1-3%
volatile oil containing 1,8-cineole, p-cymene, kessane and a novel C1
5H26O sesquiterpene. The latter gave (+)-delta-selinene on treatment w
ith trimethyliodosilane. COSY, FLOCK and NOE difference NMR experiment
s indicated cis-dihydroagarofuran. Infraspecific oscillation between k
essane and cis-dihydroagarofuran as major component in Prostanthera wa
s noted and hedycaryol proposed as a plausible common precursor.