Structure and origin of the two major monoaromatic hydrocarbons in a tasmanite oil shale from Tasmania, Australia

The structures of the two major components in the aromatic fraction of an Australian tasmanite, the tricyclic compound 13,14-dimethylpodocarpa-8,11,13-triene (C19) and the tetracyclic ring-D monoaromatic terpene (C23), were elucidated by 1H and 13C NMR. A common acyclic polyisoprenoid precursor is suggested for the compounds from a combination of genetic relationships with other members of respective homologous series and similar carbon isotopic composition for both compounds.