Some essential oils of the South Pacific

Abstract

The essential oils of ten species of plants endemic to New Zealand (Agathis australis, Lophomyrtus bullata, Lophomyrtus obcordata, Neomyrtus pedunculata, Pseudowintera colorata, Pseudowintera axillaris, and Paesia scaberula), Australia (Leptospermun citratum) Norfolk Island (Araucaria heterophylla), and Chile (Araucaria araucanu)were studied and 49 constituents identified. Of these, 4-methyl-l- phenylpentane-1,3-dione (87), 2-isopropyl chromone (88), isopimara-8,15- diene (33), and geraniolene (71) have not previously been isolated from a natural source and this is only the second time that (-)atisirene (39), (-)-isoatisirene (59), dehydroabietane (37a) and (-)-trachylobane (41) have been isolated. A critical review of the biosynthesis of terpenes found in essential oils is included and probable routes for the biosynthesis of the new and uncommon compounds are discussed in detail. The means of representing the biosynthesis of the tetra- and pentacyclic diterpenes are discussed fully and a more meaningful representation proposed. It was concluded that the sesquiterpene hydrocarbon "y-amorphene" (51) isolated from Amorpha fruticosa by Mot1 et al. (1966) was identical to y-muurolene (50) from Pinus sylvestris and Agathis australis.