Synthetic Studies To Asteriscanolide’s Skeleton

This thesis focuses on the total synthesis of asteriscanolide,and it consists of the following two chapters.Chapter 1: First of all,the types and sources of sesquiterpenes natural products were introduced.Especially,isolation and activities of the representative compound asteriscanolide,and the synthetic progress of some research groups were introduced in detail.The key steps involved in these synthetic routes include ring-closing metathesis,Pauson-Khand cycloaddition,Rh(I)-catalyzed cycloaddition,and free radical cyclization etc.Chapter 2: A nickel-catalyzed [4+4] cycloaddition developed by Wender group for total synthesis of sesquiterpene asteriscanolide was firstly introduced.Synthetic progresses on its carbocyclic skeleton by other research groups were then mentioned.The nickel-catalyzed tandem cyclization developed by our group was also utilized for a construction of carbon ring skeleton embedded in this molecule.Due to the conformation of eight-membered ring,difficulty was encountered during its construction.Although various nickel sources and ligands were screened to try to form the desired eight-membered ring,unfortunately,all failed.Since the color property of these model substrates is not obvious under UV-Vis irradiation,the carbocyclic skeleton with a phenyl group was designed.Once again,the target product was still not obtained.