Synthetic Studies Towards Galanthamine And Diocollettines A

The total synthesis of natural products is one of the most important fields in modern organic synthesis research and plays a vital role in drug development.Total synthesis can not only determine the structure of natural products,but also realize the efficient creation of natural products,it can stimulate the innovation of synthetic methodologies and promote the development of organic chemistry.To date,although the research on the total synthesis of natural products has made important progress,there are still many challenges to be faced.Synthesizers still take the development of efficient and concise synthetic strategies as the main goal.This thesis selects the natural products Galanthamine and Diocollettines A with important biological activities as the target to carry out synthesis research,which is mainly divided into the following three chapters:Part Ⅰ: Firstly,the development history and significance of total synthesis of natural products are mainly summarized.Part Ⅱ: The origin,biological activity and structural characteristics of Galanthamine are briefly introduced,and the related synthesis work of Galanthamine is reviewed.Discovered a new strategy for constructing the tricyclic skeleton of hydrodibenzofuran.By screening the types of palladium catalysts,phosphine ligands and bases,the optimal reaction conditions were determined.Through substrate expansion,10 tricyclic skeletons containing hydrodibenzofuran were obtained.Taking this strategy as the key reaction in the synthesis of Galanthamine,Galanthamine was formally synthesized after three route adjustments.Part Ⅲ: The isolation,identification,biological activity and structural characteristics of Diocollettines A were briefly described,and the research work on its total synthesis were briefly summarized.The retrosynthetic analysis of Diocollettines A was proposed,and the metalcatalyzed homopropargyl alcohol cyclization reaction and intramolecular inverse-electrondemand oxa-Diels-Alder reaction are regarded as the key reactions in the synthetic strategy.Two synthetic routes were explored to obtain a new structure of oxepane and furan,which laid the foundation for the later total synthesis of Diocollettines A.