The Application Of Phosphoramidites In Palladium Catalyzed Asymmetric Allylic Alkylation Reactions

Palladium catalyzed allylation is one of the most important methods for the formation of carbon-carbon and carbon-heteroatom chemical bonds.In palladium catalyzed asymmetric allylation reactions.Chiral ligands are basically exploited as chiral source to control the stereoselectivity.However,phosphoramidites,a kind of important trivalent phosphines,are seldom used in palladium catalyzed asymmetric allylation.This thesis describes palladium catalyzed asymmetric allylic allylation reaction using simple alkenes as allylating reagents and chiral phosphoramidites as ligands.We have established an asymmetric three-component cascade reaction of 1,3 dienes with aryl iodines and sodium dialkyl malonates under the catalysis of a palladium complex of chiral phosphoramidite ligand.The reaction underwent a cascade process of a Heck insertion of aryl group and asymmetric allylic alkylation.The asymmetric version of 1,2-difunctionalization of 1,3-dienes has been accomplished,affording the corresponding products in good yields,regio-and enantioselectivities.The asymmetric allylic C-H alkylation reaction of terminal olefins with pyrazol-5-ones has been established by the cooperative catalysis of a palladium complex of chiral phosphoramidite ligand and Br(?)nsted acid.The reaction afforded the chiral N-heterocyles containing an all-carbon quaternary stereogenic center in high yields and with high levels of regio-and enantioselectivities.More importantly,a family of new chiral phosphoramidite ligands have been found to show great potential in asymmetric allylic C-H functionalization reactions.An asymmetric allylic C-H alkylation reaction of 1,4-dienes with azlactones enabled by the catalysis of apalladium complex of chiral phosphoramidite ligand favors the generation of Z-dienyl branched products in high yields and with excellent levels of regio-,diastereo-and enantioselectivities.The products have been applied to the synthesis of structurally divergent a,a-disubstituted a-amino acid derivatives by classical transformations.