| As a kind of active intermediates,nitrene plays an important role in the synthesis of nitrogen-containing compounds.Amide skeleton structure widely exists in drug molecules and bioactive molecules,and amide compounds can be constructed quickly and efficiently by inserting C-H bond through nitrene.At present,nitrene transfer reactions catalyzed by a variety of transition metals,including rhodium,iridium,ruthenium,copper,cobalt,iron and silver,have been developed.However,when multiple active sites exist,the regioselectivity control of the reaction remains a challenge.In the above studies,there are few reports on amide transfer reaction with cheap iron salt as catalyst.Therefore,this paper is mainly based on the cyclization reaction with iron salt as catalyst and N-substituent protected amide as precursor.Through the design of different substrates,the intramolecular N-cyclization bromination reaction of Nmethoxyamide catalyzed by iron salt as nitrene precursor and the iron salt catalyzed quinolinone synthesis reaction of N-pivaloyloxyamide as nitrene precursor under light were realized respectively.The specific research contents are as follows:1.Intramolecular N-cyclization bromination of o-alkynyl benzamide promoted by iron saltAn intramolecular N-cyclization bromination reaction of N-methoxyamide as a precursor of nitrene catalyzed by iron salt was developed.By screening the reaction conditions such as catalyst,temperature and solvent,the optimal reaction conditions were obtained: o-alkynyl benzamide as substrate,0.5 equiv iron bromide as catalyzed and bromination reagent,1,2-dichloroethane as solvent at 60 °C for 8 hours to obtain bromoisoindolone-1-one compounds.The reaction has good applicability to all kinds of substituted substrates.2.Intramolecular cyclization of N-pivaloyloxyphenylpropionamide catalyzed by iron salt under lightAn iron salt catalyzed intramolecular cyclization of N-pivaloyloxyphenylpropionamide under light was developed.The reaction underwent ipso addition and C-C migration,and a series of quinolinone compounds were prepared.The optimum reaction conditions were obtained by screening the reaction conditions such as catalyst,temperature and solvent: using N-pivaloyloxyphenylpropionamide as substrate,3 w Blue LED as light source and 0.2 equiv ferric chloride as catalyst,the quinolinone compounds were efficiently obtained by reacting with 1,4 dioxane as solvent at 60 °C for 4 hours(yield 50%-90%).The reaction has high selectivity and synthetic application prospect. |
