Studies Towards [3+2]-annulation Of Arynes And Application Of Aza-prins Reations In Some Natural Products Syntheses

This thesis examined the reaction of arynes which were regarded as the important reaction intermediates and some nitrogen-containing substrates for constructing the multisubstituted hydrocarbazoles,which provides the methodological reference and new ideas for the synthesis of natural products with important physiological activity.On the basis of the development of aza-Prins-annulation in our group,we continued the application of the new form aza-Prins-annulation in the total synthesis of complex natural products,especially the alkaloids such as the lycodine alkaloids,cylindricine alkaloids and lepadifomine alkaloids.The full text contains the following four chapters: Chapter1.Applications of the aza-Prins-annulation in natural products synthesis(Review).The various reactions forms of aza-Prins-annulation are briefly introduced,and we present a large number of examples of the application of this reaction in the synthetic field separately according to the complexity of the nitrogen-containing ring system.Finally we make a prospect of the future development and breakthrough of this reaction.Chapter2.[3+2]-Annulation of Aryne for Constructing the Multisubstituted Hydrocarbazoles.A brief introduction of the discovery and the development of arynes is provided.Different kinds of methods for constructing the hydrocarbazoles previously are summarized.On the basis of the previous work,a new form of [3+2]-annulation is proposed to construct the hydrocarbazoles.Through the screening of the reaction conditions,the optimal conditions of the reaction were finally determined,and the target product was obtained in high yield.The applicability of the reaction substrate has been extensively expanded and a great deal of work has been done in terms of the gram-scale preparation and derivatization of the product.Chapter3.Study on the total synthesis of lycodine-type alkaloid ?-obscurine.A brief introduction of the separation of ?-obscurine,as well as previous synthetic works is provided.On the basis of our group's total synthesis of lycopodine alkaloids,we decided to use the aza-Prins-annulation to construct the tricyclic skeleton.On the constructing of the last ring system,we met difficulties and tried a variety of methods hoping to solve the problem.The work is onging.Chapter4.Study on the total synthesis of Cylindricine C and Lepadifomine-type alkaloids.A brief introduction of the separation of cylindricine C and lepadifomine-type alkaloids,as well as previous synthetic works is provided.The total synthesis of cylindricine C was explored by the strategy of aza-Diels-Alder/aza-Prins cascade reaction.And the total synthesis of lepadifomine-type alkaloids was explored by the strategy of N-acyliminium ions induced alkyne aza-Prins-annulation.This part of the work is still in progress.