Synthetic Applications Of Sulfonyl Hydrazides And Acylhydrazides Via Dehydrazination

In recent years,cheap and easily available hydrazine derivatives have been increasingly used in the efficient construction of carbon-carbon bonds and carbonheteroatomic bonds via dehydrazation.Among them,sulfonyl hydrazides have been developed successfully as sulfonylating agents,arylating agents,fluoroalkylating agents,and sulfenylating agents,and acylhydrazides have been developed successfully as acylating agents and arylating agents.On this basis,we studied the dehydrazylation of benzylsulfonyl hydrazides,difluoromethyl sulfonyl hydrazides and aliphatic acylhydrazides,and developed a series of new methods for the formation of carboncarbon bonds and carbon-heteroatomic bonds,further expanded the range of synthetic applications of hydrazine derivatives.This thesis is divided into four chapters.Chapter 1:Advances in synthetic applications of sulfonyl hydrazides and acylhydrazides via dehydrazinationIn this paper,the research progress of sulfonyl hydrazides in dehydrazylation reactions is reviewed according to the classification of sulfonyl hydrazides as arylating agents,fluoroalkylating agents,and sulfenylating agents.Secondly,some organic reactions involving acylhydrazides via dehydrazination as acylating agents and arylating agents are also discussed.Chapter 2:Some new reaction studies with benzylsulfonyl hydrazides as benzylating agentsBenzylsulfonyl hydrazides are first developed as a new benzylating agents by the study of the catalytic oxidation benzylation reaction of quinoxalin-2(1H)-ones.Using 10 mol%CuCN as catalyst and 2 equiv of DTBP as oxidant,a series of benzylsulfonyl hydrazides and quinoxaline-2(1H)-ones are smoothly subjected to direct benzylation reaction in 1,2-dichloroethane,giving 3-benzylquinoxalin-2(1H)-ones with wide functional group tolerance,moderate to good yields,and excellent C-3 selectivity.Radical capture experiments show that benzylsulfonyl hydrazides are oxidized in this reaction to form benzyl radical intermediates.Chapter 3:Some new reaction studies by using CF2HSO2NHNHBoc as difluoromethylthiolating agentsBy studying the difluoromethylthiolation reaction of indoles,CF2HSO2NHNHBoc is first developed as an effective difluoromethylthiolating agents.Using 10 mol%CuCl as catalyst and 1 equiv of 12 M HCl as acid additive,CF2HSO2NHNHBoc conducted smoothly direct difluoromethylthiolation reaction with a series of substituted indoles in acetonitrile,producing 3-indolyl difluoromethylthioethers with wide functional group tolerance,moderate to good yields and excellent C-3 selectively.In addition,CF2HSO2NHNHBoc can also be used as difluoromethylthiolating agents in the direct difluoromethylthiolation reaction of electron-rich aromatic compounds.The mechanism experiments show that CF2HSO2NHNHBoc generates difluoromethionyl radical intermediates under the action of HCl and CuCl.Chapter 4:Some new reaction studies by using aliphatic acylhydrazides as alkylating agentsBy studying the tandem alkylation/cyclization reaction of N-aryl acrylamide compounds,aliphatic acylhydrazides are used for the first time as a novel alkylating agents.Using 10 mol%CuCO3 as catalyst and 3 equiv of DTBP as oxidant,a series of aliphatic acylhydrazides and N-aryl acrylamides in 1,2-dichloroethane conducted smoothly tandem alkylation/cyclization reactions,providing a series of 3,3-dialkyl oxindole compounds with a wide range of functional group tolerance,medium to excellent yields.In addition,aliphatic acylhydrazides can also be used as effective alkylating agents in the direct alkylation reaction of N-aryl amide analogues and electron-deficient heterocyclic rings compounds.The radical capture experiments showed that aliphatic acylhydrazides are oxidized during the reaction,removing hydrazyl and carbon monoxide,resulting in alkyl radical intermediates.