Studies On Synthesis Of Indole Alkaloid Melotenine A

Monoterpenoid indole alkaloid Melotenine A was isolated from Melodinus tenuicaudatus.Due to its characteristic multicyclic framework and the variety of biological properties,we are interested in the chemical synthesis of this alkaloid.Melotenine A has an unprecedented skeleton with a 6/5/5/6/7 pentacyclic ring system,containing a twisted 1,3-diene unit in dihydroazepine E ring,which has a large ring strain energy.There are certain challenges in organic synthesis.In this thesis,Melotenine A is selected as the target molecule,and the construction of seven-membered ring with 1,3-diene unit in this molecule is investigated.This thesis mainly includes the following four chapters:Chapter I: The isolation,structure,bioactivity,biogenesis and progress on the synthesis of Melotenine A are described.Chapter II: The previous work about synthesis of Melotenine A at our group is discussed in detail,and the problems encounted during the investigation of various synthetic strategies are discussed.Chapter III: Based on Conia-ene reaction to construct the conjugated diene seven-membered ring of the indole alkaloid Melonenine A,we synthesized some model substrates and made attempts to close E ring of Melotenine A.Chapter Ⅳ: The synthesis of Melotenine A based on formal [5+2] annulation is studied.Starting from the molecular structure,we designed and examined a [5+2] model reaction,and the construction of seven-membered ring has been preliminary accessed.