Synthesis Of Chiral-?-amino Acids And Dithiane Compounds Via Iridium-catalyzed Asymmetric Allylic Alkylation

With the development of chiral small molecules in the fields of medicine,materials and pesticides,asymmetric allylation has been widely applied in the synthesis of chiral small molecules since it is an important method for the formation of carbon-carbon bonds and carbon-heterobonds.Due to its outstanding advantages,such as high yield,high selectivity,mild reaction conditions,excellent functional group compatibility and extensive applicability of substrate,the catalyst system of iridium complex of chiral phosphoramidite ligand has been particularly favored by chemists.This dissertation focuses on the formation of chiral carbon-carbon bond that is based on the iridium-catalyzed asymmetric allyl alkylation reaction using simple and available substrates.Firstly,the transition metal-catalyzed asymmetric allylic substitution reaction introduced,and the research progress and application of the iridium-catalyzed asymmetric allyl substitution reaction in related fields in the recent decades is reviewed.Secondly,the feasibility of the bimetal synergistic catalysis system is studied and corresponding work is developed,after which a series of optically active chiral-?-amino acid compounds with high yields and enantioselectivities are synthesized,not only realizing the synthesis of 2-amino-3-cyclopropylbutyric acid for the regulation of plant growth hormone in gram units but also efficiently synthesizing key fragments of the natural cyclic ester peptide Haepteptins A/B with strong anti-inflammatory activity.Thirdly,the intermolecular asymmetric allyl alkylation of?-substituted allyl carbonate and 1,3-dithianes catalyzed by Iridium and chiral phosphoramidite ligand is introduced.A series of allyl alkylation products with potential biological activity were synthesized with excellent substrate compatibility and enantioselectivity under mild experimental conditions.Additionally,the intramolecular asymmetric alkylation reaction of 1,3-dithiane-2-carboxylate allyl ester is discussed in detail,while the thiophene and double bond in the product can be easily converted into other functional groups maintaining better enantioselectivity.The intramolecular and intermolecular asymmetric allyl substitution reactions complement each other,which provides a feasible strategy for the synthesis of more optically pure compounds containing thiane skeletons.Finally,the study on the dicarbonyl alkylation reaction of aniline at the para position is briefly described.This reaction used easily available styrene and phenylacetylene as starting materials in the I₂/DMSO catalytic system to construct a series of C4-dicarbonyl compounds of aniline with excellent chemoselectivity and regioselectivity.