| There are more than 2000 species and 250 genera in Apocynaceae.In this dissertation,the syntheses of aspidofractinine indole alkaloids which belong to kopsia and aspidosperma family are completed.These monoterpenoid indole alkaloids are natural products with complex fused ring structures and important biological activities.Therefore,these indole alkaloids have attracted great interests of organic chemists for a long time.We have completed the divergent total syntheses of four aspidoactinine alkaloids.This paper is mainly divided into two chapters:In chapter one,the isolation,biogenenic hypothesis,structural classification,and bioactivities of these alkaloids from the genus of kopsia and aspidosperma are introduced in detail.The syntheses of aspidofractinine indole alkaloids and structurally related alkaloids are fully detailed,and the biomimetic transformations between them are briefly summarized.In chapter two,the separation and bioactivities of indole alkaloids aspidofractinine,N(1)-methyl-14,15-didehydroaspidoactinine,N-formylasidofactinine and related alkaloids are described with a brief introduction of the research background of semipinacol rearrangement reaction for the construction of the core skeleton of complex natural products.On the basis of the structural characteristics of aspidofractine and the long-term research interest of semipinacol-rerrangement reaction from our group,we designed and developed a Bischler-Napieralski/ semipinacol-rearrangement/Mannich tandem reaction that could effectively construct the two spiro quaternary centers in the C2 and C7 positions as well as the aza five-membered ring of aspidofractinine alkaloids.Then,we successfully expanded the cyclopentanone into cycloheptanone by sequential ring-expansion reations.Finally,we established the final piperidine ring of aspidofractinine by an intramolecular Aldol reaction of amide to aldehyde,which enabled the total syntheses of aspidofractinine,N(1)-methylaspidofractinine,N(1)-methyl-14,15-didehydroaspidofractinine,and N-formylaspidofractinine. |
