Fused ring systems in natural product synthesis

Abstract

On the instigation of A/Prof C. S. P. McErlean I investigated the rapid synthesis of fused ring compounds by a key polyene cyclisation. Chapter 1 sets the scene by highlighting deficiencies in literature syntheses of selected fused-ring compounds, where synthetic strategies are often suboptimal. In particular, the scarcity of reported syntheses involving a direct cyclisation method is noted. Chapter 2 discusses the taiwaniaquinoids and previous synthetic approaches including McErlean group efforts which delivered the non-natural stereochemistry. A method to produce the desired trans stereochemistry of ()-taiwaniaquinone G was developed. Attempts to apply this methodology to a divergent synthesis of the taiwaniaquinoids are detailed. Chapter 3 extends this strategy to the attempted synthesis of compounds with a greater number of rings: the dasyscyphins, pelorol, atomarianone B and disidein. The successful partial cyclisation and subsequent full cyclisation of two farnesylarenes was reported. Larger architectures remain an elusive goal. Chapter 4 discusses efforts in the synthesis of a different class of fused-ring compounds: the marine polycyclic ethers. The application of newer methodologies to the synthesis of the polycyclic ethers is described, however this did not lead to a viable strategy to these compounds.