Studies On The Total Syntheses Of Dasyscyphin D,E,Mitchellene B And Asymmetric Robinson Annulation Catalyzed By Chiral Phosphoric Acid

This thesis mainly focused on the total synthesis of dipertene-type nature product: Dasyscyphin D. Meanwhile, syntheses of Dasyscyphin E and Mitchellene B were also studied. And asymmetric Robinson annulation catalyzed by the chiral phosphoric acid was studied. This thesis consists of the following four chapters:Chapter1. Total syntheses of dipertene-type nature products.(review)In this review, based on the type of the skeletons of the diterpenoids, we divided the diterpenoids into chain diterpenoids, bicyclic diterpenoids, tricyclic diterpenoids, tetracyclic diterpenoids and macrocyclic diterpenoids. On this basis, We listed some total syntheses of the diterpenoids which have important physiological activities. And we cited the total syntheses of diterpenoid natural products in our group.Chapter2. Total syntheses of dasyscyphin D and EThree synthetic strategies toward the syntheses of the terpenoids natural products Dasyscyphin D and E were proposed. Finally, the first, concise and efficient total synthesis of (±)-Dasyscyphin D was acomplished by the third strategy in9steps with22.6%overall yield. The key steps involved PtCl2-catalyzed pentannulation reaction and double acid catalyzed Robinson annulations.Chapter3. Asymmetric Robinson annulation catalyzed by chiral phosphoric acidStudies on the asymmetric Robinson annulation catalyzed by the chiral phosphoric acid were demonstrated. This methodology used2-indanones and1-chloro-3-pentanone as the substraties, and a varieties of chiral phosphoric acids were prepared as the catalysts.Chapter4. Studies on the synthesis of mitchellene B Studies on the synthesis of mitchellene B were demonstrated. The key steps involved Hajos-Parrish reaction and Pauson-Khand reaction. We had carried out a series of attempts of the choice of the promoters in the Pauson-Khand reaction. This synthetic efforts will pave the way for the total synthesis of mitchellene B.