One-pot Reductive Tandem N-Alkylation Of Nitroaromatics

The N-alkylation reaction is an important reaction in the chemical industry,which is involved in the synthesis of many chemical products,biological intermediates and pharmaceuticals.The typical N-alkylation reaction is Ullman C-N coupling reaction.With the increasing demands of society for green chemistry,the problems of low selectivity,hash reaction conditions,environmentally-unfriendly additives in the previously-reported catalytic system need to be solved urgently.In recent years,the research on the reaction of amine alkylation by hydrogen borrowing strategy has become a highlight in this field.Amine is known to be produced by the reduction of low-cost and readily available nitro-compounds.Therefore,one-pot reduction of nitro-compounds and tandem N-alkylation has the advantage of economic steps.In this thesis,a series of iridium amido complexes has been synthesized and used in Nalkylation reaction under hydrogen-borrowed strategy.One-pot reductive tandem N,Ndimethylation and one-pot reductive tandem N-benzylation of nitro compounds under mild conditions have been developed respectively.For the one-pot reductive tandem N,N-dimethylation of nitro compounds,methanol was employed as a green,cheap,and easily available carbon source.Amido iridium complexes were found to be able to catalyze the tandem reaction successfully.In the reaction,methanol also acts as a solvent and hydrogen source.Nitroarenes can be efficiently and selectively transformed into N,N-dimethyl products at 90? by adding only trace amounts of potassium carbonate.The highest GC yield and selectivity can reach 100%,and the highest separation yield can reach 97%.Under the optimal reaction conditions,this catalytic system can effectively convert 15 substrates into corresponding N,N-dimethyl products and two substrates into corresponding N-methyl products.In addition,aniline,N-methyl aniline,and imine intermediates were observed by using in situ infra-red.A possible catalytic mechanism was proposed accordingly.For the one-pot reductive tandem N-benzylation,water was used as the green solvent,benzyl alcohol as employed as the benzylation reagent and hydrogen source.Under the catalysis of the amido iridium complexes,one-pot reductive tandem N-benzyl reaction of nitro compounds was achieved.In the reaction,nitroarenes can be converted into N-benzyl anilines with high efficiency and selectivity at 100 ?.The highest GC yield can reach 93%.The successful development of green N-alkylation catalytic system in this thesis based on the borrowing hydrogen strategy with amido iridium complexes has laid the foundation for the realization of green and highly efficient N-alkylation reaction.