Design,Synthesis And Investigation On Catalytic Properties Of PAR₃-Au Complexes Supported By Triazole (TA)

Recently,great progress has been made in gold catalysis in the field of homogeneous catalysis.With the design and preparation of new ligand compounds and Au catalysts,various novel coordination modes and chemical reactions of Au ions have been explored and studied.Phosphine ligands are commonly used ligand compounds,which promote the innovative development of gold catalytic reactions.Among them,1,2,3-triazole(TA),as a functional group,has strong coordination ability with Au ions and hydrogen bond acceptance ability.Therefore,a series of new gold catalysts were designed and prepared with organically combining gold catalysts,phosphine ligands and 1,2,3-triazole(TA),which were utilized to investigate hydroamination reaction,A₃ asymmetric coupling reaction and Au(I)redox reaction in this paper.This paper consists of four parts,part one is the Au(I)-catalyzed hydroamination,part two is the design,synthesis and resolution of a new axially chiral biaryl TA-PPh₂ ligand,part three is TA-PPh₂-Au(I)catalyzed A₃ asymmetric coupling reaction and part four is the Au(I)-catalyzed redox reaction.1.Study on intermolecular hydroamination of alkynes and aliphatic amines catalyzed by TA-Au-P metal complexesTransition metal catalyzed intermolecular hydroamination of the arylalkynes with aliphatic amine is generally problematic due to good coordination between amine and metal cation.With the combination of 1,2,3-triazole coordinated gold(I)catalyst(TA-Au)and Zn(OTf)₂ cocatalyst,this challenging transformation was achieved with good to excellent yields(93%)and regioselectivity(> 20 : 1)with a large scope of amine choices(>50 examples).Compared with previously reported methods,this approach offered an alternative catalyst system to achieve this fundamental chemical transformation with high efficiency and practical conditions.2.Design,synthesis and resolution of a novel axially chiral biaryl TA-PPh₂ligandWe developed the design and preparation of novel axially chiral biaryl ligands,and proposed the synthesis of chiral triazole skeleton induced by ?-? stacking of aromatic rings.A series of 1,2,3-triazole(TA)chiral biaryl ligands were synthesized,such as TA-PPh₂.It is obvious to find that the prepared triazole system has excellent coordination ability and potential application value.Combined with the commonality of two types of axial chiral molecules and extensive investigation of the relevant literature on the chiral resolution of traditional BINOL series axial chiral molecules,many types of optical resolution methods were applied.Interestingly,Stack-TA-OH was successfully resolved by amino acid esterification.The optically pure chiral molecule Stack-TA-PPh₂(> 99% ee)can be obtained by coordination,crystallization and dissociation of Stack-TA-PPh₂ with chiral palladium salt.The crystal of the obtained Stack-TA-OH was analyzed,and the basic skeleton of Stack-TA axis chiral molecule was also determined.The thermal stability of optically pure Stack-TA-PPh₂ was studied.It was found that Stack-TA-PPh₂ had strong thermodynamic stability at 65 oC and below.The experimental results show that the C2 position on the naphthalene ring with large functional groups can dramatically enhance ?-? stacking,which can provide sufficient steric hindrance and improve the thermodynamically stable axial chirality of molecular Stack-TA-PPh₂.The results show that the triazole system designed in this chapter has excellent coordination ability and potential application value.3.A new chiral catalyst TA-PPh₂-Au(I)was designed and prepared to catalyze the A₃ asymmetric coupling reaction of aldehydes,secondary amines and alkynes.The axially-chiral metal complexes j-a(TA-PPh₂ Au Cl)and j-b(TA-PPh₂ Au OTf)2 were designed and prepared.The axially-chiral metal complexes j-a(TA-PPh₂ Au Cl)and j-b(TA-PPh₂ Au OTf)2 were characterized and studied by 1H NMR,13 C NMR,31 P NMR,XRD,single crystal diffraction and elemental analysis.At the same time,we also determined the spatial structure and coordination mode of axially chiral compound TA-PPh₂.By investigating the literature,we studied the catalytic A₃ asymmetric coupling reaction between aromatic formaldehyde,secondary amine and alkyne through chiral biaryl series metal complex TA-PPh₂ Au.This challenging transformation was achieved with good to excellent yields(93%)and ee value of asymmetric coupling product(66%)with a large scope of substrate choices(14 examples).Through this reaction,we have a better understanding of our new chiral biaryl system compounds,which provides an experimental and theoretical basis for the later research group to study such new axial chiral biaryl system compounds.4.Au(I)redox catalyzed cyclization of allyl Cyclohexanedione compounds with aryldiazonium saltsBy exploring the effects of concentration,temperature,various Lewis bases and their equivalents,various solvents and catalysts on the cyclization of allyl Cyclohexanedione,we obtained the optimal conditions for the cyclization of allyl Cyclohexanedione series compounds.Then we carried out substrate expansion(16examples)to obtain satisfactory substrate adaptability and good catalytic effect.The highest separation yield of cyclization reaction was 93%.This is the first example to realize the cyclization of allyl 1,3-Cyclohexanedione catalyzed by transition metal catalyst to prepare functionalized dihydrofuran molecules,which provides a new promising route for the preparation of functionalized furan molecules and their derivatives.This study further broadens the scope of gold redox chemistry.