Extended ketones of the tricyclic terpane series in a Tasmanian tasmanite bitumen

The following novel ketones of the extended tricyclic terpane series (cleistanthane skeleton) were identified in the ketone fraction of a Permian tasmanite bitumen from Tasmania, Australia by HRGC—MS—C and HRGC—MS—MS—C—SRM:C20; the C23 13,14-stereoisomers ββ,αβ,βα,αα; the C28 and C33 diastereomers R/S βα and R/S αα; and higher homologs in lower relative abundance. These tricyclic terpane ketones may be derived from oxidation of the side chain of a tricyclooctaisoprene. The proposed biological precursor for these series is tricyclooctaprenol (C40), derived from cyclization of octaprenol in the tasmanites algae.