Studies On The Total Syntheses Of Daphenylline,Malabanone A,Polyrhaphin D And Marginatone

This dissertation is mainly focused on studies of the total syntheses of daphniphyllum alkaloid daphenylline,triterpenoid malabanone A and spongian diterpenoids polyrhaphin D and marginatone.It consists of the following three chapters: Chapter 1.Advance in Total Syntheses of Spongian Diterpenoids(review)In this chapter,the isolation,nomenclature,structural characters and bioactivities of spongian diterpenoids were briefly introduced at first.Then the synthetic endeavors towards the three classes of spongian diterpenoids were reviewed mainly based on their synthetic strategies.Chapter 2.Synthetic Studies toward the Daphniphyllum Alkaloid DaphenyllineIn this chapter,the previously reported synthetic highlights of the daphniphyllum alkaloid daphenylline were summarized firstly.Then,two synthetic strategies were exploited in the construction of its unique ring systems: 1)construction of the ABC(6/6/5)tricyclic framework of daphenylline by a double Michael addition reaction starting from the inexpensive commercially available natural carvone;2)assembling the ACD(6/5/7)tricyclic framework via an intramolecular [3+2] cycloaddition reaction catalyzed by [Rh] starting from the carvone as well.Chapter 3.Synthetic Studies toward Malabanone A,Polyrhaphin D and MarginatoneIn this chapter,two strategies were attempted toward the total synthesis of malabanone A : 1)construction of BCD(6/6/5)tricyclic framework of malabanone A starting from carvone using a Diels-Alder reaction as the key reaction;2)assembling the ABC(6/6/6)tricyclic framework of malabanone A through double Robinson cyclization reactions.Meanwhile,the total synthesis of spongian diterpenoids polyrhaphin D and marginatone has been achieved via several chemical conversions starting from the obtained tricyclic compound.