Palladium Catalyzed Tandem Reaction Via C-H Activation With Structurally Modified Norbornenes

Chapter ⅠThe first chapter introduces the origin of the Catellani reaction and the development of the palladium/norbornene reaction system.Based on this reaction mechanism,it was found that norbornene plays a crucial role in the catalytic cycle,but there are also selectivity issues,as most by-products contain norbornene structural units.(1)the intermediate of aryl-norbornyl-palladacycle(ANP)directly reductive eliminated C-C to form benzocyclobutenes;(2)the oxidation between the electrophilic reagent and C(sp3)-Pd bond of the intermediate(ANP),not the required C(sp2)-Pd bond;(3)the β-carbon difficultly eliminated of norbornene without ortho substituents,and the second C-H palladation takes place,which is ortho constraint.Then,norbornene modified with different structures was introduced to solve the selectivity in Catellani reaction.Chapter ⅡCarboxylate-assisted palladium/norbornene cooperative catalyzes the Catellani reaction,which is compatible with the ortho-amination and unactivated C(sp2)-H arylation.A series of 1-amino substituted dihydrophenanthrene,phenanthrene and 6Hbenzo[c]chromones were synthesized by this method.Based on kinetic isotope experiments,the kinetic curve showed that pivalic acid can effectively increase the reaction rate of unactivated C(sp2)-H activation,and this rate is consistent with the formation rate of palladium aryl-norbornyl-pentacyclic(ANP)intermediate.Chapter ⅢPalladium/norbornadiene cooperative catalyzes the Catellani reaction,which is compatible with ortho-amination and [2+3] or [2+4] cyclization.This method could be applied to ortho-methyl substituted iodoarenes and ortho-phenyl substituted iodoarenes.In terms of mechanism,the density functional theory(DFT)calculation proved the reaction sequence of the formation of palladium aryl norbornene five-membered ring(ANP)intermediate and the C(sp3 or sp2)-H activation.Chapter ⅣPalladium/structurally modified norbornadiene(smNBDs)cooperative catalyzes the Catellani reaction,which is compatible with C-H glycosylation and retro-DielsAlder reaction.Structurally modified norbornadiene(smNBDs)could effectively regulate the reactivity of aryl-norbornadiene-palladacycle(ANP),construct high chemoselectivity and regioselectivity,and the C4-glycoside indole is unsubstituted at C2 and C3 positions.This method could be applied to chlorinated six-membered and five-membered glycosides,as well as different N-alkyl(primary,secondary and tertiary)iodoaromatics.In terms of mechanism,X-ray single crystal diffraction experiments and density functional theory(DFT)calculations had proved that the migration and insertion of structurally modified norbornadienes(smNBDs)and phenylpalladium intermediates have high chemo-and regioselectivity.Chapter ⅤPalladium/chiral norbornene(smNBEs)cooperative the Catellani reaction.Chiral norbornene(smNBEs)stereoselectively controls the aromatic axial chirality and further stereoselectively induces ferrocene into undergoing C(sp2)-H activation.In terms of mechanism,the density functional theory(DFT)calculation proved the catalytic model of chiral norbornene with substrate and the reaction process of axial-to-planar surface.