Total Synthesis Of Chaetophenol C

This dissertation deal with the total synthesis of natural product Chaetophenol C as well as the methodology development for quick assembly of its core skeleton.It includes three chapters.Chapter 1:Current research progress of oxa Diels-Alder reactions.In this chapter,a review of oxa Diels-Alder reactions was described.Firstly,traditional catalytic oxa Diels-Alder reactions such as Lewis acid catalytic,organocatalytic,amino acid derivatives catalytic,hydrogen bonding compounds catalytic and chiral amines catalytic were documented including their synthetic applications.A brief introduction of Oxonium ionic Diels-Alder reactions was also presented.This variation of oxa-Diels-Alder reaction became more and more attractive in synthetic community due to its high reactivity which could be potentially involved in many cascaded reactions.Chapter 2:Background of Chaetophenol CIn this chapter,background of natural product Chaetophenol C was described.To date,there is no synthetic report about Chaetophenol C due to its structural uniqueness,which makes its total synthesis more important to biological,chemical and medical research.The biosynthetic hypothesis enlightened us to construct its core skeleton by a one-pot oxonium ionic Diels-Alder cascade reaction,although a lot of challenges such as reactivities,steroselectivities and quench manner are still remained.Chapter 3:Total synthesis of natural product Chaetophenol CIn this chapter,the total synthesis of Chaetophenol C has been extensively investigated.Initially,the model reactions for critical oxonium ionic Diels-Alder cascade have been systematically studied.Pd(II)proved to be the optimal catalyst among Cu Ag Au,and Pt ever tested which led to the desired polycylic product with high yield and stereoselectivity.Based on the success of this model reaction,total synthesis of Chaetophenol C has been sequentially carried out.The first tactics which based on the desymmetrisation of phloroglucinol failed.Then the strategy was adopted 2-Methylresorcinol as the starting material,through reactions like Suzuki-Miyaura coupling,Claisen rearrangement and oxa Diels-Alder cascade reaction,the desired polycylic key intermediated was successfully synthesized.After removing the protecting group and installing the terminal dimethyl group via CM reaction,Chaetophenol C would be successfully obtained.This part of work is still in progress.In addition,we also investigated the scope of our oxonium ionic Diels-Alder cascade reaction,the comprehensive understanding of this novel transformation will definitely facilitate its applications in other natural products synthesis.