Ni-Catalyzed Synthesis Of P-Stereogenic Compounds And Their Transformations

P-stereogenic phosphines are of great significance in synthetic chemistry,which have been widely used in organic chemistry,pharmaceutical synthesis,materials and polymer science.In recent years,with the rapid development in the field of asymmetric organic synthesis,the diversity of structures and functions of P-stereogenic phosphines has been continuously developed by researchers from multiple disciplines.Compared with the conventional ligands with carbon or axial chirality,P-chiral compounds have the advantage of being closer to the reaction center,which may generate unique properties in asymmetric synthesis.Chapter 1 mainly introduced the research significance and synthesis strategy of P-stereogenic phosphines.In spite of the significance of P-chiral compounds in many fields,strategies towards their construction seems very scarce.Here,we summarized the strategies which were reported previously to access P-stereogenic phosphines and the progress which have been made in methods of catalytic asymmetric synthesis of P-chiral compounds are shown in this part.In chapter 2,the research of asymmetric allylic alkylation of secondary phosphine oxides was introduced.In this work,the chiral tertiary allylic phosphine oxides were obtained with inexpensive allylic acetates and stable secondary phosphine oxides.The reaction proceeded through a dynamic kinetic asymmetric transformation(DYKAT)pathway using racemic substrates with Ni(COD)2/(S,S)-BDPP as the catalyst.This work is the first example of nickel catalyzed asymmetric allylic alkylation of secondary phosphine oxides,which provide significant reference for further relevant research.Accordingto the monitoringofthe reaction mixture,the kinetic resolution and dynamic kinetic asymmetric transformation process were compared intuitively.Further study revealed that the Ni(Ⅱ)species which was the resting state played the key role in this reaction.The work introduced in chapter 3 was nickel-catalyzed asymmetric hydrophospination of alkynes.The secondary phosphines,were prepared in-situ with high efficiency from PhSiH3 and bench stable secondary phosphine oxides,which could be used directly in the subsequent catalytic reaction.In this case,the problem of the high air-sensitivity of secondary phosphines in the preparation and purification process was solved.In addition,the chiral vinyl P(Ⅲ)compounds from the nickel catalysis can be derivatized in a variety of ways.For example,P-stereogenic phosphine sulfides,phosphine boranes,phosphine oxides,phosphine selenides,iminophosphorane and quaternary phosphonium salts can be synthesized respectively.These compounds may serve as potential organocatalysts and phase transfer catalysts.In addition,P(Ⅲ)products can also be used directly as ligands to synthesize a variety of chiral transition metal complexes,which has demonstrated the powerful application prospects of our strategy.Moreover,the C-C double bond in our products can also be used as another significant fulcrum for molecular modification.For example,potential bidentate ligands like P-P,P-N and P-S were also afforded with a variety of nucleophiles by 1,4-addition pathways.This paper was summarized in chapter 4.More importantly,the challenges and problems remaining in this field were also been discussed.We hope that more valuable strategies and attentions could be put into the field of constructing P-stereogenic phosphines.