Studies towards tricyclic sesquiterpenes

• Main Author: Henry, S. G.
• Published: University of Cambridge 2008
• Subjects: 547.71
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603969

There has been considerable interest in the synthesis and biological properties of sesquiterpene lactones as a result of their cytotoxic activity. This manuscript describes a concise synthesis of the elemanolide model compound 3.1 and studies towards the synthesis of 8-deoxyvernolepin 1.6. The first chapter will deal with sesquiterpene motifs, culminating in the introduction of elemanolides and eudesmanolides. Isolation and biological activity of elemanolides (particularly vernolepin) will be presented, along with a possible biosynthesis and selected previous syntheses. Chapter two details the role of manganese triacetate in oxidative radical reactions, highlighting the main differences between manganese and tin. A brief outline of work done in our group on oxidative cyclisations with manganese(III) acetate is included, along with examples of tethered cyclisations. Chapter three discusses an enantioselective route to a model compound of 8-deoxyvernolepin 1.6 utilising an enantioselective Diels Alder reaction, followed by attempted 1,3-transpositons of stereochemical information. Chapter four describes a racemic synthetic pathway to both 8-deoxyvernolepin 1.6, the model compound 3.1 and subsequent analogues, using a racemic Diels-Alder reaction, palladium-mediated π-allyl substitution and tin-mediated radical substitution.