Abstract:
A highly toxic diterpene ester, prostratin, has been isolated from Pimelea prostrata. The properties of this compound are shown to be extremely similar to phorbol, the parent alcohol of the co-carcinogenic diesters recently isolated from Croton oil. A revised structure (19-56) is proposed for phorbol and (20-56) is proposed for the structure of prostratin. The previously proposed formulation of pododacric acid as (33a-127) is shorn to be incorrect by the synthesis of the latter from podocarpic acid (1-125). Note to the reader: Throughout the majority of this thesis, diagrams, tables and figures are recorded as (x-y) where x refers to the diagram, table or figure number and y refers to the appropriate page number. In part II, diagrams 1-38 on the fold-out pages 125-127 are recorded as the diagram number only, and furthermore, these diagrams represent the normal A-B trans ring system where the C-5 hydrogen has the α configuration. The numbering systems for the different carbon skeletons discussed are shown in diagrams (10-55), (12-55), (19-56) and (2-125). The normal αβ convention for terpenes and steroids is used, viz. β refers to the front of the molecule and is represented by full line bonds and a refers to the rear or underside of the molecule and is indicated by dotted bonds.