Cycloaddition Reactionsof Isoquinolinebased C,N-Cyclic Azomethine Imine

N-heterocycles are important motifs in many natural and bioactive compounds,which possess a broadspectrum of applications as pharmaceutical and agrochemicalproducts,and functional materials.Therefore,it is highlydesirable to develop mild and straightforward protocols for their synthesis.The thesis is mainlyfocused on the highly efficient synthesis of heterocyclic compounds through cycloaddition reactions.A formal [3 + 3] cycloaddition of isoquinoline based C,N-cyclic azomethineiminewith difluorocyclopropene has been developed.It provides biologically important 2H-pyridazino[6,1-a]isoquinolin-2-onederivativesin good to excellent yields.The difluorocyclopropene was found to be a novel three-carbon synthon.This protocol features mild conditions,high efficiency,and wide substrate scopes.We have developed a mild and efficient method for the synthesis of polysubstituted pyrroles derivatives through the base mediated 1,3-dipolar cycloaddition between in situ formed nitrile ylides anddicyanocyclopropene.This reaction proceeds through a tandem [3 + 2] cycloaddition,ring-opening and aromatization,leading to the cycloadductsin moderate to good yields.The dicyanocyclopropene work as two-carbon synthon in this process.