The Study On Acid Promoted Tandem Carbonylation/Bicyclization Of Diaryl Alkynes

N-Containing heterocyclic skeletons are valuable structures in pharmaceutical molecules,thus their synthesis has been extensively explored.This thesis mainly focuses on the two types of transition-metal-free eyclization reactions for the efficient constructionof N-beterocycles:one is an acid promoted tandem carbonylation/bicyclization of diaryl alkynes,and the other is a transition-netal-free fluoroaiylation of diazoacetamides.1.Acid Promoted Tandem Carbonylation/Bicyclization of Diaryl AlkynsAn unprecedented atom-economic tandem bicyclization of diaryl alkynes has been disclosed,which provides a streamline access to a range ofpolycyclic 2N-indazoles in high to excellent yields.The salient features of this reaction include readily available starting materials,good fimctioml group compatibility,mild and transition-metal-free reaction conditions,no column chromato graph,high bond-formation efficiency,and ease in further transformations.Notably,this is the first exarpple for the synthesis of indazoles with in situ generated diazonium salt as the nitrogen source,and a mechanistic rationale involving an acid promoted tandem diazonium salt formation/bicyclization process is also discussed.2.Transition-Metal-Free Fluoroarylation of DiazoacetamidesAn efficeent transitton-metal-free fluoroarylation reaction of N-aryldiazacetamides with NFSI(N-fluorobenzenesulfonimide)is described.This reaction directly provides 3-fluorooxindole derivatives in high ylields with high selectivity via a carbene-free process under mild reaction conditions.