Copper-catalyzed Multi-component Cascade Reaction To Construct Multi-substituted 1,2,3-triazoles

Multi-substituted 1,2,3-triazoles are very important azole compounds,which occupy an important position in many fields such as the modification of existing drugs,the development of new drugs,biochemistry,medicinal chemistry,agricultural chemistry,and material chemistry.The traditional copper-catalyzed cyclization of organic azides and alkynes(Cu AAC)is the most favorable tool for the construction of disubstituted 1,2,3-triazoles and has the advantages of mild reaction conditions,high conversion efficiency,and good regioselectivity.A multicomponent cascade reaction developed on the basis of copper-catalyzed azide cycloaddition of alkynes has emerged as the most powerful approach to construct Multi-substituted 1,2,3-triazoles.But at present,the functionalization types of the products synthesized by this method are not rich enough,and the reaction mode is relatively simple.Therefore,it is very meaningful to develop more copper-catalyzed multi-component cascade reactions to construct multi-substituted 1,2,3-triazoles with diverse functions and structures.This thesis contains the following two parts:(1)The recent research progress in the construction of multi-substituted 1,2,3-triazoles and catalyzed by transition metal is reviewed,which is described by the reaction classification of three alkynes: Enyne,terminal alkyne and alkynic acid.(2)A three-component t reaction of terminal alkynes,organic azides,and elemental selenium is described in detail.Diselenide compounds with Se-Se bonds are widely used.In many methods of synthesizing diselenide compounds,using elemental selenium as a selenium source has its irreplaceable advantages.For the first time,we have achieved the construction of bistriazolyl diselenides by the copper-catalyzed cascade reaction of terminal alkynes,organic azides,and elemental selenium.The reaction has the characteristics of simple and easy-to-obtain raw materials,mild reaction conditions,high atom economy,and good regioselectivity,and can be scaled up to the gram scale.Mechanistic studies indicated that the transformation may involve dipolar cycloaddition of terminal alkyne and azide,oxidative addition of selenium,and reductive elimination.This reaction provides an efficient and concise route for the construction of bistriazolyl diselenides.