The Synthesis Of Axially And Helically Chiral Compound:Palladium Catalyzed Asymmetric Macrocyclization And Ring-opening Reactions

Atropisomeric compounds are a class of chiral compounds which contain an axis with a set of substituents so that it cannot rotate freely and be non-superposable with their mirror image.They are widely used in the fields of asymmetric catalysis,materials and biomedicines.The synthesis of the atropisomeric compound is the popular area of organic chemistry in recent years.This article mainly focused on transition metal catalyzed construction of axially chirality and included the following three parts:Chapter I:The Total Synthesis of Atropisomeric Natural Product Isoplagiochin D.Isoplagiochin D is a 16-membered macrocyclic bisbibenzyl compound which contains a high ring strain and hindrance so that a biphenyl structure in the macrocycle cannot rotate freely.The only successful strategy of synthesis this compound is an asymmetric Heck cyclization reaction controlled by chiral sulfoxide auxiliary group.We have developed a catalytic asymmetric method to prepare Isoplagiochin D via palladiumcatalyzed asymmetric macrocyclization between benzyl halides and carbenes.Excellent enantioselectivity has been achieved by using WingPhos as the chiral ligand.It showcased an efficient way for catalytically asymmetric construction of macrocycle.Chapter Ⅱ:Palladium Catalyzed Asymmetric Ring-Opening Reaction of 8Hindeno[1,2-c]thiophen-8-ols.Axially chiral arylthiophenes are useful in material science while their catalytic synthesis is rarely reported.We have developed an atroposelective kinetic resolution of 8H-indeno[1,2-c]thiophen-8-ols via Pd-catalyzed C-C bond cleavage reaction to obtain axially chiral thiophene-phenyl ketones and central chiral ols.We studied its reaction mechanism and proposed a plausible reaction model.We also found the point to axial chirality transfer of optically active 8Hindeno[1,2-c]thiophen-8-ols to corresponding axially chiral thiophene-phenyl ketones under achiral condition.Briefly investigation of the synthetic applications of the obtained thiophenyl atropisomers were performed.Chapter Ⅲ:Palladium Catalyzed Asymmetric Ring-Opening Reaction of Helicene Alcohols.Helicene compounds is a class of molecules contained a plurality of fused aromatic(hetero)rings which showed helical chirality.Based on the reaction model of the kinetic resolution in Chapter Ⅱ,we have realized it for helicene derivatives which contained five-membered ring tertiary alcohol structure and could get helicene alcohols with high enantiopurity.These helicene alcohols have been successfully converted to helical chiral carbocation compounds which may be used as Lewis acid to approach asymmetric catalysis.