Dehydrazinative Coupling,Addition,and Rearrangement Reactions Of Hydrazine Derivatives

Substituted hydrazines are a common class of organic compounds,which have widely applications in pharmaceutical chemistry,polymer materials,and dyes.In organic synthesis,the early research on the hydrazine derivatives mainly focused on the reduction of double bonds and the synthesis of five-membered heterocyclic compounds.As the research progresses,chemists have found that hydrazine derivatives can remove the-NHNH2 group under oxidative conditions.Based on this,we have demonstrated hydrazinecarboxamides react as new carbamoylating agents through the dehydrazinative reaction with electron-deficient nitrogen heteroarenes,the tandem carbamoylation/cyclization reaction of N-arylacrylamides.And also,we realized aryne-induced[2,3]-? rearrangement reaction of tri-substituted allylic/propargyl hydrazines.This dessertation includes four chapters.Chapter l:Research progress in the reaction of hydrazine derivatives.Recently,there were many reports on the dehydrazinative reaction of substituted hydrazines by cleaving the C-N bond.Five kinds of substituted hydrazines are conmmon used,such as aryl hydrazines,aroyl hydrazines,sulfonyl hydrazines,carbazates and phosphorohydrazidates.In this chapter we give an overview of the reactions of hydrazine derivatives on the coupling reaction and the addition reaction through C-N bond cleavage.Chapter 2:Highly regioselective carbamoylation of electron-deficient nitrogen heteroarenes with hydrazinecarboxamidesWe firstly discover that hydrazinecarboxamides can be used as a novel carbamoylation agent.With 5 mlol%of CuCO3 as catalyst,25 mol%of AICl3 as Lewis acid,3 equiv.of TBHP as oxidant,and DMSO as solvent,hydrazinecarboxamides can undergo the dehydrazinative Minisci reaction of electron-deficient nitrogen heteroarenes.The reaction gives a highly regioselective and chemoselective to afford structurally diverse nitrogen-heteroaryl carboxamides.Preliminary study of the reaction mechanism show that hydrazinecarboxamides were gradually oxidized to carbamoyl radicals and then undergoes C-H functionalization with nitrogen heteroarenes.Chapter 3:Tandem carbamoylation/cyclization reaction of N-arylacrylamides with hydrazinecarboxamidesWe report a series tandem carbamoylation/cyclization reaction of N-arylacrylamides with hydrazinecarboxamides.The reaction conditions were simple,only 1 mol%of CuCO3 and 4 equiv of TBHP were used.The reaction avoids usinga large excess of carbamoylation agents.This reaction shows a broader range of substrates,and very good tolerance of different functional groups(cyano,nitro,hydroxyl,ester,halogen,pyridyl,etc.).Chapter 4:Aryne-induced[2,3]-sigmatropic rearrangement of tri-substituted allylic/propargyl hydrazinesFor the first time,we realized the[2,3]-? rearrangement reaction of the tri-substituted allylic/propargyl hydrazines under mild conditions.A range of allylic/propargyl hydrazines bearing various substituent groups smoothly underwent[2,3]-sigmatropic rearrangement to furnish structurally diverse tetrasubstituted hydrazines in moderate to good yields.In addition,we have a more detailed understanding of the reaction mechanism through the deuteration experiments and the separation of the reaction intermediates,and proposed that the substituted allylic/propargyl hydrazines generate allylic/propargyl zwitterions intermediates in situ by using arynes.