Synthesis Of Aryl-Substituted Aniline Derivatives Via The Palladium-Catalyzed Ligand-Free Suzuki Reaction

Aryl-substituted aniline derivatives have been extensively used in the synthesis of dyes, pharmaceuticals, ferromagnetic materials, and organometallic complexes. The palladium-catalyzed Suzuki reaction confirmed to be an efficient way to construct aryl-substituted aniline derivatives. Until now, the protocols reported in the literatures were usually promoted by oxygen and/or moisture sensitive phosphines, which were difficult to synthesize. The phosphine-promoted reactions are always combined with long times and low yields. Therefore, a general, simple and efficient protocol to prepare aryl-substituted aniline derivatives will have important application.Due to the advantages of β-diketiminates:strong electronic donor properties, steric parameters and readily adjusted electronic properties, excellent coordinative ability to metals, and easy to synthesize, in recent years, the research in the β-diketiminates and related metal complexes has become a hot topic in the area of organic chemistry. However, the β-diketiminates bearing2,4,6-trisarylphenyl and2,6-bisarylpheyl groups are rarely reported. In this thesis, a simple, efficient, aerobic and liand-free Suzuki protocol has been developed to prepare mono-, bis-, and tris-aryl-substituted anilines, which were further used to synthesize β-diketiminates. The main contents are as follows:An efficient Pd(OAc)2-H2O/DMF (N,N-dimethylformamide) procedure for the Suzuki cross-coupling reaction of bromoanilines with arylboronic acids under air has been developed. After a systematical study on the model cross-coupling of2,4,6-tribromoaniline with phenylboronic acid, the optimized reaction conditions were obtained:Pd(OAc)20.5-1.0mol%, K3PO4·7H2O, DMF:H2O=2:1(volume ratio),80℃, in air. Under the optimized reaction conditions, the couplings of2,4,6-tribromoaniline,2,6-dibromo-4-nitroanilne,2,6-dibromoaniline or4-bromoaniline with different arylboronic acids were completed in short times and gave good to excellent isolated yields of the corresponding products. Among them, the reaction of2,6-dibromo-4-nitroaniline with4-methylphenylbronic acid could be completed in15min and provided a99%isolated yield.With the Suzuki cross-coupling products in hand, we tried to carry out the reactions between these products and1,1,3,3-tetramethoxylpropane or2,4-pentandione to afford a series of β-diketiminates.