Study On The Copper-Catalyzed One-Pot Synthesis Of Nitrogen-Containing Heterocyclic Compounds

Copper-catalyzed cross-coupling reaction serves the new strategy for the formation of C-C, C-N and C-O bonds. The novel one-pot procedure for multicomponent coupling reaction is carried out in dispensing with further purification of the intermediates and simplifying the procedure. It has been highlighted as one of the research frontiers in organic chemistry. In the dissertation copper-catalyzed Ullmann-type coupling reaction and multicomponent reaction have been studied. Twenty-five new nitrogen-containing heterocyclic compounds were synthesized in one-pot procedure. The synthetic topic is novel, which has its great originality and research value.The copper-catalyzed one-pot synthesis of benzimidazo[1,2-a] quinolines was studied starting from 2-(1H-benzo[d]imidazol-2-yl) acetonitrile and 2-bromobenzaldehyde. The possible mechanism was studied. 2-(1H-benzo[d]imidazol-2-yl) acetonitrile reacts with 2-bromo- benzaldehyde known as Knoevenagel condensation followed by an intramolecular C-N coupling reaction. The influence of solvent, ligand, base and temperature on the reaction had been investigated. The reaction was carried out in the yield of 84% with 5% mol CuI, 20% mol 1,10-phenanthroline and 2.0 eq. K2CO3 in dioxane under 90℃. The scope of substrates was subsequently examined. Unsubstituted benzimidazo [1,2-a]quinoline was synthesized in the yield of 90%.The copper-catalyzed three-component reaction in one-pot procedure was studied starting from acetylene, p-toluenesulfonyl azide and 2-bromoallyamine. The possible mechanism was studied. The [3+2] cycloaddition between terminal alkynes and azides is conducted in the presence of CuI and TEA. The ketenimine intermediate is attacked by 2-bromoallyamine to give N-Sulfonylamidine derivatives, followed by an intramolecular C-N coupling reaction. In order to screen the optimal reaction condition, the influence of solvent, temperature, ligand and base was investigated on the sequential C-N coupling reaction. The reaction was carried out in the yield of 60% with 10% mol CuI, 20% mol N,N'-dimethylethane-1,2-diamine and 2.0 eq. K2CO3 in the mixed solvents of CH3CN and DMSO (the volume ratio is 2∶1). The scope of substrates was subsequently examined.25 new compounds synthesized were characterized by 1H-NMR, ¹³C-NMR and HRMS analysis. Copper-catalyzed one-pot synthesis of nitrogen-containing heterocyclic compounds shows some advantages such as simple experimental procedure, mild reaction condition, moderate to good yield and superior to step economy.