Study On Formation And Reaction Of Nitrogen Free Radicals Of Hydrazones Compounds

Hydrazones compounds are important intermediates in organic synthesis due to their simple preparation,convenient storage,and stable properties.Moreover,They can realize various forms of chemical transformation reactions.Therefore,they have received extensive attention from many chemical scientists.When it comes to the reaction of free radicals,hydrazones react with free radicals(radical receptors),and it is also easy to generate nitrogen-centered radicals under mild conditions(radical donors).In the case of a free radical acceptor,hydrazones contains an unsaturated C=N bond and can react with difluoro or perfluoroalkyl radical,nitrogen radical,and phosphorus radical.In recent years,the radical reaction of hydrazones has achieved vigorous development.The N-H bond of hydrazones could be oxidized to produce active nitrogen radical species,and then can proceed tandem reactions with unsaturated olefins and alkynes.Many scientists have obtained many biologically active nitrogen-containing heterocyclic compounds by this method,such as indazole,pyrazole derivatives.However,there are few methods to generate hydrazones-nitrogen radicals at present.In this regard,it is important to develop a new method with wider universality.Combining fluorochemical and transition metal catalysis in this paper,we have been generated the nitrogen-centered free radicals of hydrazones by different methods to realize intermolecular C-H bond amination and intramolecular cyclization reactions.The main research content is as follows:(1)The halogen-bond could be formed through a transiently generated amidylanion with perfluoroalkyl halide.Thermal or visible-light irradiation of the halogen-bond adduct induced a single electron transfer(SET),thus allowing easy access to hydrazones-nitrogen radicals.Perfluoroalkyl iodide is also used as H-abstraction reagents and finally afford the amination product.(2)Using a cheap metal Cu as a catalyst,the N-H bond of ?,?-unsaturated hydrazones are oxidized to generate a nitrogen central radical and undergo intramolecular cyclization to form a six-membered heterocyclic compound.In this reaction,the ?-position is non-activated olefins of hydrazones are used as a substrate,and dihydropyridazine or pyridazine compounds can be selectively obtained by controlling the progress of the reaction through the selection of a solvent.