| Chirality is a ubiquitous phenomenon in nature. Almost all the importantbiological macromolecules are chiral, such as proteins, carbohydrate and nucleic acids.A large number of research results show that in the field of synthetic drugs in itseffectiveness in chiral drugs and chiral molecule. Up to now, the methods to obtainthe chiral compounds are so many, among them asymmetric synthesis is the mostconvenient efficient one. In asymmetric synthesis, Pd(II)-Catalytic asymmetricreaction has all the time attracted broad attention. The metal catalysts for catalyticasymmetric are so many, such as Rhodium catalyst, copper catalyst, zinc catalystetc., while Palladium catalysts and ligands are developed in recent years and showgood potential in the field of asymmetric synthesis.The application of palladium acetate and chiral ligand catalyst in the asymmetriccoupling reaction and arylation of N-Acyl-N,O-acetals is studied in this paper.Asymmetric coupling reaction and arylation of N-acyl-N,O-acetals of the transitionmetal palladium achieves high reactivity and enantioselectivity through changing thestructure of ligand and experimenting different types of ligands. In Palladiumcatalyzed asymmetric coupling reactions, nine new ligands of three types weredesigned, and four coupling substrates were synthesized by the catalysis of theseligands to evaluate and screen the function of ligands and catalysts. The temperatureof80℃,Palladium acetate (Pd (OAc)2) as catalyst, cesium carbonate as alkaline andtoluene as solvent is the best reaction conditions. The study shows that the ligandsamino acid and menthol as chiral center perform good reaction activity and selectivityexcept tert-butyl sulfoxide ligands l in this asymmetric coupling reaction. Ligandswith94%yield and50%enantioselective coupling products are screened out. Thishas laid a good foundation of the extension of our later chiral ligands and the study ofasymmetric coupling reaction.In Palladium catalyzed asymmetric coupling reactions and arylation ofN-Acyl-N,O-acetals,16new compounds with different substituents and location weresynthesized based on the consideration of electronic effect and steric effect of groups,and the elimination of addition reaction of N-(ethoxy(4-nitrophenyl)methyl)-benzamide and boron anhydride catalyzed by Palladium as a model to screen the newsynthesized ligands and reaction conditions. Dichloroethane as solvent, the reactiontemperature at60℃,Palladium acetate as catalyst, bipyridine as ligands and arrangedin the open is the best condition. The results show that the stereoselectivity ofproducts is determined by the chiral center of ligand. Although our new synthesizedligands have not been very good application in the reaction, R-Binap ligand has very good performance. While the steric effect and electronic effect of product itself hasgreat influence on the stereoselectivity. From the reaction results, the reaction activityof the designed new ligands is very good in the Palladium catalyzed asymmetriccoupling reaction. We investigated the palladium catalyzed arylation ofN-Acyl-N,O-Acetals, the results show that the yield of these new reactions between8%-84%and enantioselectivity between3%-37%. |
