Studies On Synthesis Of Malabaricane And Isomalabaricane Triterpenoids

This thesis mainly consists of four chapters:(1)Isolation and synthesis of malabaricane and isomalabaricane triterpenoids;(2)First generation synthesis of Pauson-Khand reaction as the core strategy;(3)Second generation synthesis of HAT reaction as the core strategy.Chapter 1: Isolation and synthesis of malabaricane and isomalabaricane triterpenoids.The natural products of malabaricane and isomalabaricane are triterpenoids with a6/6/5 tricyclic core skeleton,which can be isolated from plants,animals and microorganisms.In this chapter,the sources,structural characteristics,biological activities and synthesis of these two natural products were introduced.Chapter 2: First generation synthesis of Pauson-Khand reaction as the core strategy?Pauson-Khand reaction can quickly construct cyclopentenone ring structure,which is widely used in the total synthesis of natural products.We used Pauson-Khand reaction to construct the 6/6/5 tricyclic skeleton,but enylene ring isomerization reaction occurred to construct 6/5 union ring.Chapter 3: Second generation synthesis of HAT reaction as the core strategy?Hydrogen atom transfer reaction is a kind of free radical reaction initiated by transition metal.It has good chemical selectivity and functional group tolerance.HAT reaction has unique advantages in the construction of five-membered or six-membered rings.We successfully constructed the core skeleton of malabaricane and isomalabaricane triterpenoids by HAT reaction.