Synthesis Of Pyrazolederivatives By 1,3-dipolar Cycloaddition Reaction Of Nitrile Imine

Pyrazole,one of the most common heterocyclic structures,is widely found in natural products and drug molecules with significant biological activity,and has important applications in drug and agriculture.Moreover,some pyrazoles are used in polymer chemistry and food industry,while some have liquid crystal properties.Substituted pyrazoles have also been applied as ligands for transition metal-catalyzed reactions.It is highly desirable for the development of a direct method for the synthesis of pyrazole derivatives.This thesis is based on in situ formation of nitrile imine as a key intermediate,two methods of regioselectivity synthesis of substituted pyrazole were developed,the content is as follows:Firstly,we described copper(I)iodide catalyzed tandem reaction of ?-chlorohydrazone and acetylene,using a pot method to facilitate the effective synthesis 1,3,5-trisubstitute-1H-pyrazoles,this reaction obtain the ?,?-alkynylhydrazone by the nucleophilic addition of the acetylene to the in situ formed nitrile imine,and in the role of copper under the action of molecular electrophilic cyclization reaction to Synthesis pyrazoles.Secondly,we have developed a efficient method for the synthesis of fully substituted pyrazoles with ?-chlorohydrazone and cycloprop-2-ene-1,1-dicarbonitrile via a 1,3-dipolar cycloaddition reaction,this method has the characteristics of simple operation,mild reaction condition etc.