Study On Novel Copper Catalytic Systems For C-N/C-O Coupling Reaction To Synthesize Of N-Aryl Imidazoles And Benzoxazoles

N-arylimidazoles and benzoxazoles are common and useful motifs in medicine, biological and natural products. So the arylation of imidazoles and the synthesis of benzoxazoles have very important significance in organic synthesis.The N-arylation of imidazoles and benzoxazoles can be synthesized by the classic Ullmann-type coupling reactions. It are often suffered from the harsh condition invoving elevated temperature, long reaction time and stoichiometric amounts of copper reagents, which restrict the application of the reaction. However, with the further development of the study on the Ullmann reaction, the reaction condition has been reinvigorated by the implementation of the ligand.Therefore, recently the chemists devote themselves to designing and opitimizing the liagnd of copper.This thesis commits to exploit the catalytical system of the “copper/ligand”, based on the previous work, to develop and optimize the C-N or C-O coupling reaction. The specific work is as follows:The first part explains that the arylation of imidazole was finished by the system of the CuI/nitrogen azole carboxylic acid. Firstly, the copper resource, base, solvent, temperature and the amount of the catalysis were measured one by one, the best condition: Cu I(5 mol%), L 1(10mol%), DMSO, Na OH, 110℃, 12 h. And then, the amount of the substrates which were characterized by 1 H NMR had been reached to thirteen with the yield 74-96% under the best condition.The second part describes that the coupling of imidazole and halide arene could carried out by the copper(0)-pyridine N-oxide complex in water. First, there were four pyridine N-oxide ligand were synthesized. An then, the reaction condition was screened and achieved, the optimal condition: Cu(10 mol%),L8(20 mol%), KOH, 120℃, 12 h. The scope of the substrates which were characterized by the 1HNMR was made and reached to fourteen with the yield 39-97% under the best condition. At last, the reaction of imidazole with 1-iodo-4-methoxybenzene can be enlarged in gram scale.The third part indicates that the synthesis of benzoxazoles strating from N-(2-Halophenyl)benzamide could be catalyzed by the copper-methyl-2-methoxybenzoate complex. First, the reaction condition was examined and got, the best condition: CuI(10 mol%),L9(20 mol%), DMF, K3PO4, 90℃, 12 h. With the best condition inhand, 19 kinds of substrates which were characterized by 1H NMR and 13 C NMR were successed to be prepared. The benzoxazoles could be prepared from the primary amides and o-dihalobenzene via the C-N and C-O coupling reaction in a single step.In sumary, This thesis establishes two kinds of copper catalysis system for the N-arylation of imidazoles in organic solvent and water. The methods with the promising and practical appication could improve the reaction condition, shorten the reaction time. At the same time, This thesis alsosets up a copper system for the intramolecular coupling O-arylation to synthsize the benzoxazoles,which has the advantages of inexpensive, more wider scope of substrates and mild reaction condition and so on. In a word, this thesis is very key to develop and consummate the Ullmann reaction.