Construction Of Nitrogen-containing Heterocycles By Cyclization Of Electron-deficient Alkynes

Nitrogen-containing heterocycles are one of the most important heterocyclic compounds in organic chemistry.Nitrogen-containing heterocyclic skeletons are ubiquitous in natural products and various artificial drug molecules.Therefore,the development of simple and efficient methods to synthesize nitrogen-containing heterocycles has always been the focus of our research on organic chemical synthesis.Electron-poor alkynes have been widely used as starting materials for organic synthesis methodological studies due to their excellent addition and tandem reaction properties.Our research focuses on the construction of nitrogen-containing heterocycles from electron-poor alkynes.In this paper,we mainly discuss the synthesis of nitrogen-containing heterocycles with quinolizinone,pyrrole and isoquinoline skeletons by the tandem cyclization of electron-poor alkynes,including the following three parts:(a)A one-pot synthesis of quinolizinones from iodoarenes,methyl propiolate and 2-alkylazaarenes was reported.The reaction has good functional group tolerance,especially the unsaturated double bonds and triple bonds can also be compatible with the reaction system,and the corresponding target products can be obtained with good yields.(b)A Cu-catalyzed for the synthesis of pyrrole compounds from the cyclization of oxime esters and ynals in moderate to excellent yields was developed.The advantages of this transformation included good functional group tolerance,easily available raw materials,simple operation,etc.(c)An efficient Rh-Cu bimetallic co-catalyzed toward isoquinolines by the cyclization of oxime esters and ynals was described.The reaction was compatible with various electron-donating and electron-withdrawing groups.The Rh complex was used to activate the C-H bond on the orthoposition of the benzene ring and then form the isoquinoline products.These products containing aldehyde group have great potential application value in the field of medicine chemistry.