Studies On The Synthesis Of Mollactones A-C,Mollolide A And Antroalbocin A

In this thesis,we mainly studied the synthesis of the grayanane diterpenes Mollactones A-C and Mollolide A and the sesquiterpene Antroalbocin A.It contains three chapters.Chapter 1 The advances of synthetic strategies toward bicyclic [3.2.1] skeleton and their applications in total synthesis of natural terpenoids(review)In this chapter,we introduce the construction methods and strategies of [3.2.1]bridge rings according to the type of reaction.Then we reviewed their applications in total syntheses of natural diterpenes and sesquiterpenes.Chapter 2 Synthetic studies towards Mollactones A-C and Mollolide AIn this chapter,we firstly summarized the structure characters and possible related biogenesis relationships between Mollactones A-C and Mollolide A.Then we designed three routes to synthesize Mollactones A-C.In the first route,we used a Pd-catalyzed desymmetric α-alkylation reaction of carbonyl compounds as a key reaction,but we didn’t obtain the desired bicyclic [3.2.1] product after extensive reaction conditions screening.So we turned to the second route and tried to build the required bicyclic[3.2.1] skeleton through a ring-opening reaction of the 5/5/3 tricyclic precursor.However,this route was soon abandoned due to the difficulties we met during the preparation of the required key intermediate.Eventually we moved on to the third route.And this time we successfully obtained the key tricyclic product.The follow-up work is underway.Chapter 3 Synthetic studies towards Antroalbocin AIn this chapter,we firstly introduced the the background and previous synthetic studies towards Antroalbocin A.Then starting from 2,4-dimethoxybenzaldehyde,we prepared the key precursor through a series transformations including Pd/C reduction hydrolysis,o-formylation,Grignard reagent addition,selective demethylation and reduction of the hydroxyl group.With the key precursor in hand,an oxidative dearomatization [5+2] cyclization was attempted without success.We also tried to obtain the reaction precursor from o-cresol through several functional group conversions and continue to exam the designed tandem oxidative dearomatization/ [5+2]cyclization reaction.This work will be carried out by other people in this lab.