C–N Bond Borylation Of Unactivated Aromatic Amines

The aromatic amine is an important organic compounds.Their skeletons are widely found in the molecules of various drugs,pesticides,dyes and organic materials.In recent years,the carbon-nitrogen bond activation conversion of aromatic amines has become a hot topic in organic synthesis chemistry.The carbon-nitrogen bond activation of primary aromatic amines is mainly through the pre-activation strategy to convert primary aromatic amines into active diazonium salts,quaternary ammonium salts,pyridinium salts and(sulfonamides)compounds.Because of the high dissociation energy of chemical bonds,there are few reports on the activation and conversion of carbon-nitrogen bonds of tertiary(secondary)arylamines,mainly focusing on the transition metal-catalyzed activation and conversion of carbon-nitrogen bonds of benzidine or naphthylamine with o-oriented arylamines and nickel.At present,non-ortho-guided,non-biphenyl or naphthalene-type arylamine carbon-nitrogen bond activation conversion reaction is still a challenging problem.In this paper,the related studies on the carbon-nitrogen bond activation reaction of arylamines are discussed in detail,and the study on the carbon-nitrogen bond boriding reaction of non-activated arylamines is carried out:1.Using di-tert-butyl peroxide as the radical initiator and pinacol borate as the boron source,the carbon-nitrogen bond boronation of N,N-dimethylarylamine was carried out.The intermediate yield of phenyl borate was obtained by the boriding reaction of N,N-dimethylaniline under optimized reaction conditions.Under these conditions,we have tried a series of boriding reactions of N,N-dimethylarylamine compounds,and obtained medium or lower yields.2.On the basis of the first part,the boronation of N,N-dimethylarylamine with carbon-nitrogen bond was carried out under the condition of oxygen-induced reaction by visible light.The reaction conditions are simple and mild,just need to be filled with aromatic amine and boric acid pinacol ester test tube on the blue LED lamp,can start the reaction.The reaction has excellent substrate compatibility,and a series of aromatic amine compounds containing different functional groups,including bioactive molecules containing aromatic amine skeletons,can undergo carbon-nitrogen bond boriding reactions.The mechanism of the reaction was also studied in detail.The experimental results showed that the reaction experienced a radical boriding reaction with the participation of superoxide radical anions.