Efficient Synthesis Of Nickel-catalyzed Triarylamines

Triarylamines,as a special class of organic compounds with large conjugated systems,have a wide range of applications in materials chemistry,organic solar cells,photosensitizers,supramolecular chemistry and other fields due to their unique physical and chemical properties.Therefore,the development of an efficient synthesis method for triarylamine compounds has great application value.Transition metal-catalyzed CN cross-coupling is the best strategy for the synthesis of triarylamines,especially the palladium-catalyzed Buchwald-Hartwig reaction,which greatly promotes the application of triarylamines in materials.Palladium dominates in transition-metalcatalyzed C-N cross-coupling reactions,however,its high cost and scarcity have prompted constant efforts to find a cheaper and more abundant metal to replace it.Copper-catalyzed Ullmann reactions have also been used in the synthesis of triarylamines,however,such reactions usually require expensive aryl iodides for coupling with diarylamines.Although great progress has been made in the C-N crosscoupling reaction of diarylamines,the efficient synthesis of such compounds is still very challenging due to the low nucleophilicity and large steric hindrance of the diarylamine substrates.Nickel sits right above palladium on the periodic table and is one of the most important substitutes for palladium.Over the past two decades,nickel catalysis has made tremendous progress.However,only a few methods have been reported for the synthesis of nickel-catalyzed triarylamines so far,and this reaction still has a lot of room for development.We have developed a bivalent nickel coordinated by a bidentate ligand in combination with Grignard reagents for the efficient synthesis of triamines.The method is simple and efficient,and the different kinds of diphenylamine substrates can obtain the target compound in high yield,including diphenylamine,phenoxazine,phenothiazine,9,9-dimethyl-9,10-dihydroacridine,9H-Tribenzo[b,d,f]azepine,10,11-dihydro-5H-dibenzo[b,f]azepine,5H-dibenzo[b,f]azepine,9H-tris Benzo[b,d,f]azepine etc.