Study On The Transition-metal Catalyzed Synthesis Of 1,2,3-Triazole Derivatives

1,2,3-Triazoles are useful structural elements and have been widely used in pharmaceuticals, pesticides, materials and organic synthesis. There are two procedures available for the preparation of substituted 1,2,3-triazoles. Cu-catalyzed azide-alkyne 1,3-dipolar [3+2]-cycloaddition and transition-metal catalyzed C-H functionalization of 1,2,3-triazole. The former has been fully developed through several decades. The latter has gradually attracted lots of interest because of the wide application of C-H activation functionalization. The copper catalysts used in this[3+2]-cycloaddition reaction includes almost all of Cu(I) and Cu(II) compounds and complexes.Copper nanoclusters have also already been documented as catalysts for the click reaction. However, up to date, tandem reaction have rarely been reported when using Cu as catalyst for three-component click reaction. In addition, as far as we know, transition-metal catalyzed C-H functionalization of 1,2,3-triazoles mainly focused on 2-substituted 1,2,3-triazoles, whereas the reported reaction of 1-substituted1,2,3-triazoles reports were was relatively few.The thesis consists of three chapters:Chapter 1: Progress in synthesis of 1,2,3-triazole derivatives and N-alkylationThis chapter focuses on the research progress in synthesis of 1,2,3-triazoles and N-alkylation. The related literatures are reviewed in detail.Chapter 2: Nano-copper catalyzed three-component tandem cycloaddition reaction and N-alkylation reactionThe focus of this work is to develop a facile and highly efficient protocol for the synthesis of 1-alkyl-4-(N-alkylaminophenyl)-1,2,3-triazoles by one-pot,three-component tandem reaction from aminophenylacetylenes, sodium azide and alkyl halides via tandem 3+2 dipolar cycloaddition and two or three N-alkylation reaction catalyzed by copper nanoparticles. The advantages of this protocol include low amount of the catalyst(10 mol%), mild conditions(room temperature and in air),simple operation, middle to good yield(up to 87%).Chapter 3: C-5 Arylation of 1,2,3-triazoles with diaryliodonium salts under airThe focus of this work is to develop an effective method to prepare C-5 selective arylation triazoles via sp2 C-H activation that using palladium as a catalyst, whereas diaryliodonium salts served as arylating reagent. This method also showed electron-rich, electron-deficient and halogenated triazoles or diaryliodonium salts were succeed in giving the desired products with good isolated yields in 24 hours under air, and the mechanism was proposed.