Studies towards the synthesis of the guaianolide and pseudoguaianolide skeleton

A synthesis of the guaiane skeleton is presented in my thesis. Guaianolides and pseudoguaianolides are sesquiterpene lactones and share a sommon backbone: the guaiane skeleton. Hundreds of natural products belong to these families of compounds. The guaiane skeleton is characterised by a bicyclo[5.3.0]decane ring system (perhydroazulene). Among the guaianolide family, dehydroleucodine was chosen as a target example. The first part of the thesis introduces the guaianolide and pseudoguaianolide families. An overview of the biological properties and the biosynthesis are reported. First, structures from componds belonging to these families are described. Then, the biological properties of the dehydroleucodine are reported and, finally, the syntheses of three sesquiterpene lactones are shown. The second part of the thesis reports my studies towards the synthesis of the guaiane skeleton and dehydroleucodine. The key step of the construction of the perhydroazulene ring system 3 is an intramolecular ene reaction. The lactone is build through an inversion of the alcohol configuration followed by an allylic oxidation 2 and finished by an oxidation of the primary alcohol 1. A proposal of the synthesis of dehydroleucodine is briefly explained. The final part is the experimental part. O O O H guaiane dehydroleucodine O O O H HO H H O HO H H O OH H H O O O 1 2 3 4 5 Studies towards the Synthesis of the Guaianolide and Pseudoguaianolide skeleton. iii ACKNOWLEDGEMENTS My studies were performed in Professor Page’s group at the University of East Anglia (Norwich, Norfolk). I would like to thank my supervisor, Professor Phil Page for his welcome in his laboratory and the confidence Phil granted me for carrying on a subject started years ago. Of course, I can’t forget my fiancée for her daily support through those hard times of research, Doctor Yohan Chan for his help in the lab and outside, and all my lab-mates for the nice atmosphere we work in. I have a special thought to my so dear friend Franklin, who left us too early. I am sure he would have loved to read this thesis through and give it his mark and corrections. At last, I need to be grateful for the funding from the University of East Anglia