Studies On The Synthesis Of The Core Ring System Of The Doterpenoid Alkaloids Via Phenylactealdehydic [3+2]-Dipolar Cycloaddition

Azomethine ylides, an important type of allylic 1, 3-dipoles, have been widely and effectively used in constructing the multi-substituted pyrrolidine skeleton through their [3 + 2]-dipolar cycloaddition reactions with unsaturated compounds. In most cases, azomethine ylide precursors are produced by the condensation of non-enolizable aromatic aldehydes or simple aliphatic aldehydes with glycine esters, however, the use of easily enolizable phenylacetaldehyde derivatives as the precursors are not reported.In this thesis, the core skeleton of C₂₀-doterpenoid alkaloids was constructed through the development of a new azomethine ylide [3+2]-dipolar cycloaddition reaction system using easily enolizable phenylacetaldehyde derivatives. As diterpenoid alkaloids have being shown to possess signifigant bioactivities, such as analgesia, antiphlogosis, antitumor and immunoregulation, this new methodology not only provides an extension of the scope of dipolar cycloadditions, but also will find broad applications in the total synthesis of C₂₀-diterpenoid alkaloids, which would be useful for revealing the structure-activity relationships and mechanism of action of these alkaloids, and for further development of innovative drugs.