Investigation On Azide With Aldehydes/Unsaturated Aldehydes To Synthesize1,2,3-triazole Derivatives

In2001,the concept of "click chemistry" was proposed at first by Sharpless at the Scripps Research Institute. The most classic reaction in "click chemistry" was the copper(I) catalyzed azides-alkyne cycloaddtion(CuAAC)., The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been developed as a powerful tool to access1,2,3-triazole molecules,. However, the presence of the transition metal may cause copper-induced degradation of viruses or oligonucleotide strands in biological system. Additionally, copper ions are potentially toxic for living organisms. Notably, the reactions are only suited for terminal alkynes.Therefore,exploring more effective and gentle method to synthesis triazole derivates become a main issue after the CuAAC reaction.In the first part of this thesis, the organocatalytic cycloaddition of azides and unsaturated aldehydes was mainly introduced:a straightforward synthesis of triazole-olefins. Azide compound was used in the reaction with the a,β-unsaturated aldehydes in the presence of an organic small molecule amine catalysis, with strong organic base1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) as additives to achieve1,3-dipolar cycloaddition reactions. By optimizing the reaction conditions, including screening of catalysts, solvent selection, the amount of catalyst and reactants used in an amount proportional control to obtain the optimal reaction conditions in hand:diethylamine as catalyst, the reaction was stirred at50℃in DMSO within2hours, delivering the corresponding production with high yields. We developed an organocatalytic inverse-electron-demand1,3-dipolar cycloaddition reaction between various azides with unsaturated aldehydes to directly access to1,2,3-triazole-olefins and proposed the plausible mechanism.In the second part, it was demonstrated that azides with saturated aldehydes gave the1,4-disubstituted1,2,3-triazoles through one-pot protocol in the condition of the pyrrolidine taking part in the reaction and adding the MCPBA. Meanwhile, it was investigated that the types of secondary amines, ratio of reagents, temperature and solvents for obtaining the optimal reaction condition:azides:saturated aldehyde:pyrrolidine=1:1.1:1.1, at50℃, and THF as solvent,when the azides was completely consumed after12h,5.0eq MCPBA was added into the reaction at0℃and continued stirred1h at room temperature to give almost quantitative yield,67%-99%.In addition, research summary and prospects about aldehydes, ketones and azide though1,3-dipolar cycloaddition in the field of organocatalysis were wrapped up.