Functionalization Of Inert Carbon Hydrogen Bond With Maleimide And The Following Cyclization It Initiated

Maleimide and its derivatives not only exist widely in nature,but also have important applications in medicinal chemistry and material sciences due to their significant biological activities and unique optical properties.On the other hand,transition metal-catalyzed dehydrogenative cross-coupling reactions through inert C(sp~2)-H bond activation have been developed as green and economical methods for the synthesis of fused-heterocyclic compounds due to their notable features such as easy availability of raw materials,mild reaction conditions,and high atom-economy.Based on the above background,this dissertation is dedicated to the synthesis of N-fused heterocyclic compounds containing a maleimide unit via transition metal-catalyzed dehydrogenative cross-coupling via inert C(sp~2)-H bond activation by using maleimide as an economical and effective substrate.This dissertation mainly includes the following two parts:The first part of this dissertation is focused on Rh(III)-catalyzed dehydrogenative cross-coupling of 2-arylindazoles with maleimides via inert C(sp~2)-H bond activation.Through systematic screening of various oxidants,additives and solvents,a simple,efficient and reaction condition-controlled selective synthesis of indazoquinolinomaleimides and indazoloindole spiropyrrolidinones has been established.Further study on the scope of substrates showed that 2-arylindazoles and maleimides bearing various substituents attached on different sites could participate in the reactions to afford the target products with good efficiency.The second part of this dissertation is about Rh(III)-catalyzed dehydrogenative cross-coupling of 2-arylimidazopyridines with maleimides via inert C(sp~2)-H bond activation.Through systematic screening of various catalysts,oxidants,solvents and reaction temperatures,a novel and atom-economical method for the synthesis of imidazopyridinonaphthomaleimides has been established.By using this method,a series of diversely substituted products were synthesized,providing a library of candidate compounds for biological activity screening and material property test.In summary,some novel methods for the synthesis of fused N-heterocyclic compounds containing a maleimide unit have been developed based on Rh(III)-catalyzed dehydrogenative cross-coupling reactions.Compared with literature protocols,the methods developed in this dissertation have the advantages of easily available starting materials,high atom-economy,good functional group tolerance,simple operation and mild conditions.