Study On Amination At The α-carbon Of Carbonyl

α-amino ketones are a kind of important structural units,which exist in natural products and drugs widely,also are important intermediates in organic synthesis.In recent years,the synthesis methods of α-amino ketones have attracted wide attention of organic synthetic chemists,and many C-H amination reactions of α-carbonyl groups have been reported successively.Previously,the construction method of C-N bond mainly depends on transition metal catalyzed coupling reaction,which usually requires high temperature and stoichiometric catalyst.In recent years,with the development of free radical chemistry,C-H amination mediated by free radicals can generate nitrogen radical intermediates moderately and selectively,and then C-N bond could be constructed efficiently.In this paper,we developed a nitrogen radical mediated amination method for the α-site of carbonyl group.Under the catalytic system of TEMPO and NFSI,the nitrogen-center radicals has been generated,and then the free radical addition reaction occurs between nitrogen radical and the enol ester to introduce the amino group to the α-site of carbonyl group.The reaction is widely applicable to all kinds of carbonyl compounds,and has the advantages of mild conditions,high efficiency and economy and so on.This paper is mainly divided into the following two parts:In the first part,the application and synthesis methods of α-amino ketones are summarized,and the initiation methods and application of nitrogen-centered free radicals are summarized.In the second part,the method of generating nitrogen-central free radical under the catalytic system of TEMPO and NFSI was developed by our group previously,which also can be used to realize the C-H amination reaction of carbonyl group,and the optimal reaction conditions were determined through the selection of solvent,the reaction duration and leaving group.On the basis of the experimental results and literature references,we proposed the possible reaction mechanism.Unlike the well-known reported methodologies,this metal-free catalytic strategy gave a novel example for the synthesis of α-amino ketone with mild,simple and atom economic conditions.