Studies On Syntheses Of Pharbinilic Acid And Crokonoids A-C

The ent-kaurane are important part of tetracyclic diterpenoids,which have drawn continuous attention from synthetic chemist due to unique structure and high potential biological activities.They contain common bicyclo[3.2.1]octane moiety.Therefore,the straightforward synthesis of bicyclo[3.2.1]octane moiety is crucial for syntheses of tetracyclic diterpenoids.We have developed a general synthetic approach to 1-Hydroxyl allogibberic methyl ester by a key step of transannular Pinacol coupling reaction.This study is expected to provide a new approach to the GA-and allogibberic acid-type diterpenoids,and pave the way to the discovery of biologically significant lead compounds.We also devoted to the total syntheses of Crokonoids A-C.The paper contains three chapters as follows:Chapter 1.Syntheses advances of bicyclo[3.2.1]octane moiety of ent-kaurane diterpenoids（Review）.Almost three-quarters of tetracyclic diterpenoids possess a bicyclo[3.2.1]octane moiety.Synthetic chemist have developed several efficient approaches to construct bicyclo[3.2.1]octane scaffolds due to inherent reactive activities.This chapter described the recent advances in syntheses of tetracyclic diterpenoids which contain bicyclo[3.2.1]octane moiety in recent ten years.Chapter 2.Synthesis of Pharbinilic acid.This chapter mainly introduced the isolation and synthetic advance of Pharbinilic acid.We have accomplished the first de novo synthesis of 1-hydroxyl allogibberic methyl ester,en route to numerous other important bioactive molecules including pharbinilic acid.The synthesis relies on the strategic application of a Pd-catalyzed Suzuki-Miyaura cross coupling reaction to assemble two fragments,a Lewis acid-catalyzed reductive Prins cyclization reaction to construct the central cyclopentane ring,and a Sm I₂-mediated transannular Pinacol coupling reaction to construct the bridged[3.2.1]skeleton.These key reactions basically proceed in excellent chemo-and diastereo-selectivities.Chapter 3.Total syntheses of Crokonoids A-C.This chapter mainly introduced the isolation and biosynthesis of Crokonoids A-C.We expected to achieve the total syntheses of Crokonoids A-C by a key MHAT step.The bicyclo[3.2.1]octane moiety could be constructed through Conia-ene reaction.We are making effort to realize the total syntheses of Crokonoids A-C now.