Cycling Reaction Study Of α-substituted Aryl Sulfonylhydrazone

Hydrazone is a cheap,easy to obtain,safe and stable compound,which can replace unstable diazo compounds.Due to its special structure,the application of hydrazone in cyclization reaction has attracted extensive attention.The most common is the synthesis of nitrogen heterocyclic compounds such as thiazole,pyrazole and triazole through intermolecular or intramolecular interaction,Nitrogen heterocyclic compounds penetrate into all aspects of our life,so it is of certain significance to synthesize nitrogen heterocyclic compounds by cyclization of hydrazone compounds.Therefore,the research content of this thesis will focus on the cyclization of N-p-toluenesulfonyl hydrazone.The research work is mainly divided into the following three parts:In the first part,the selective synthesis of substituted arylthiadiazoles was studied.Using2-（p-toluenesulfonyl）-N-p-toluenesulfonyl hydrazone as raw material,different substituted 1,2,3-thiadiazole can be obtained by changing the reaction conditions.Under the action of K₂CO₃,2-（p-toluenesulfonyl）-n-toluenesulfonyl hydrazone can react rapidly with S₈to produce 4-aryl-1,2,3-thiadiazole.In the case of I₂as catalyst,4-aryl-5-toluenesulfonyl-1,2,3-thiadiazole can be obtained as the main product.In addition,using KSCN as sulfur source,this conversion can obtain highly selective 4-aryl-1,2,3-thiadiazole.This strategy has the advantages of short reaction time,simple reaction conditions and no transition metal catalysis,It provides an effective way for the selective construction of different substituted1,2,3-thiadiazole.In the second part,the one pot two-step reaction of 3-oxo-3-arylpropiononitrile,methyl hydrazide（or hydrazine hydrate）and arylsulfonyl hydrazide was studied.Firstly,under the action of 10 mol%iodine,3-oxo-3-arylpropionitrile and methyl hydrazine formate（or hydrazine hydrate）can be condensed and cyclized to form N-ester substituted aminopyrazole,and then 50 mol%NIS and 2.5 equiv.arylsulfonyl hydrazide are added to obtain the product of 3-aryl-4-（arylthio）-1H-pyrazole-5-amine.This strategy does not need to separate the intermediate cyclization products and simplifies the experimental steps,It saves time,has good atomic economy,mild reaction conditions and a wide range of substrate applications.In addition,the reaction can carry out gram scale experiments and the products can be further transformed,It provides a feasible method for the construction of C4 thioetherified aminopyrazole.The third part focuses on the[3+2]cyclization of 1,3-diketone or unsaturated ketone with sulfonylhydrazine.Under the action of TBAI,the product of 3,5-diphenyl-4-（phenylthio）-1H pyrazole can be obtained by cyclization and C（sp²）-H thioetherification of 1,3-diphenylpropane-1,3-dione and phenylsulfonyl hydrazine;Similarly,C4 sulfonated pyrazole derivatives can also be obtained from benzylidene acetone and p-toluenesulfonyl hydrazide under the action of NIS.This part provides a useful strategy for constructing different aryl substituted pyrazole skeletons.