Studies On The Synthesis Of Leonuketal And Securidanes A&B

This thesis mainly aims to studies on the total synthesis of leonuketal and the asymmetric synthesis of securidanes A&B,and the detail contents could be divided into the following two parts.Chapter 1.The Study on the Total Synthesis of LeonuketalThe isolation,structure identification,bioactivities of leonuketal and the synthesis of diterpenoid natural products from Leonurus.Based on the literatures,we designed a new method for constructing the bridge spiroketal fused lactone core,and planned to use this feasible strategies to synthesize leonuketal.Compound 1-104 was synthesized from monoiodide 1-95 and aldehyde 1-102,which was then transformed to compound 1-105 via singlet oxygen,The key intermediate 107 could be obtained from 1-105 through a two-step sequence.This research provides a referential route for the synthesis of similar compounds.Furthermore,we also designed a [2+2] cycloaddition strategy,and synthesized the key precursor alkene 1-120.Related works are under way.Chapter 2.The Studies on Asymmetric Synthesis of Securidanes A&BIn this chapter,firstly the isolation,structure identitication,and bioactivities of the Securidanes A&B were introduced;then the recent progresses on the asymmetric synthesis of triarylmethanes was summarized.Based on the works of pioneer researchers,we developed a new method for the construction of chiral triarylmethanes through Friedel-Crafts alkylation.Unlike other methods,in our protocol all the aryl groups of the synthesized triarylmethanes were benzene rings.