Studies On Hydroazidation Of Alkynes And Its Related Cascade Reactions

Vinyl azides are a class of structurally unique and synthetically useful functionalized alkenes。Since they were first discovery and separation by Foster,it has a long history of more than 100 years.However,they have been regarded as “sleepers” among the reactive species and have drawn little attention due to its potential for explosiveness,toxicity and instability.With the improvement of synthetic methods and the development of transition metals,the vinyl azide chemistey has attracted much attention again.Our group has focused on silver-catalyzed organic reactions in recent years.In 2014,we develpoed silver-catalyzed hydroazidation of alkynes,which is a simple and efficient method for preparing vinyl azides.This method has been greatly promoted the development of vinyl azide chemistry.In this thesis,we focus on developing some new reaction of hydroazidation of alkynes using vinyl azide as starting materials or using vinyl azide in suit as intermediates.My thesis is divided into seven Parts.Part Ⅰ: The progress of hydroazidation of alkynes.Part Ⅱ: The progress of the radical of vinyl azidesPart Ⅲ: The paper topic.Part Ⅳ: Radical Enamination of Vinyl Azides: Direct Synthesis of N-Unprotected EnaminesWe developed an electron-withdrawing-group-generable radical-induced enamination of vinyl azides,acceping a variety of β-functionalized N-unprotected enamines in a stereoselective manner.And a plausible mechanism involving an unusual 1,3-H transfer of in situ generated iminyl radical intermediate was proposed on the basis of experimental results and DFT calculations.Part Ⅴ: Silver-Catalyzed Aminosulfonylation of AlkynesIn this part,we deveploed silver‐catalyzed aminosulfonylation of alkynes through an unprecedented hydroazidation / radical addition cascade for the first time,accepting a series of free sulfonyl enamine compounds.In addition,This strategy also provides a new method of producing iminyl radicals from alkynes.Part Ⅵ: Silver-catalyzed C-to N-center Remote Arene Migration:In this part,we first reported the iminyl radical-mediated C-to-N functional group migrations using vinyl azides,accessing synthetically useful β-trifluoromethyl and β-enamino ketonesPart Ⅶ: Silver-Catalyzed Tandem Hydroazidation/Azide Cycloaddition of 1,6-diynes.In this part,we develpoed a silver-catalyzed cascade hydroazidation/ cycloaddition of 1,6-diynes,affording the corresponding 1,5-fused-1,2,3-triazoles in good-to-excellent yields.