Development Of Ni-Catalyzed Tandem Reductive Cyclizations For Total Syntheses Of Podophyllum And Dibenzocyclooctadiene Lignans

This thesis aims at the divergent asymmetric syntheses of podophyllotoxin and related family members via stereoselective reductive Ni-catalysis and studies toward total synthesis of steganone.It consists of the following three chapters.Chapter 1: This chapter described the isolation,structure,bioactivity and research progress of dibenzocyclooctadiene lignans,and then discussed two main synthetic strategies in detail.Chapter 2: This chapter described stereoselective synthesis of tetrahydronaphtho[2,3-c]furan skeletons,through intramolecular reductive nickel-catalysis of ?-bromo acetals.This method led to the efficient syntheses of several closely related Podophyllum members,including naturally occurring podophyllotoxin and analogue.Chapter 3: This chapter described the facile synthesis of bisbenzocyclooctadiene lactone,through a similar intramolecular reductive nickel-catalysis and subsequent oxidation.An attempted synthesis of steganone was discussed.