Cp~*Co(?)-Catalyzed C-H Bond Amination Of Indolines At The C7-position

Indoline and its derivatives are meaningful precursors for the synthesis of numerous natural products and pharmaceutical molecules.Among them,C7-amidated indoline has attracted considerable attention because it is the core skeleton of many pharmacologically active molecules.However,the traditional synthetic methods to aromatic amines involve cross-coupling of prefunctionalized aryl halides with amines,which means less atom-economic and environmentally benign.In recent years,transition metal-catalyzed C-H bond functionalization had received widespread attention due to its simple steps and high atomic economy.Among them,the construction of C-N bonds by C-H bond activation had achieved remarkable results.Based on our group's research on Cobalt-catalyzed C-H bond amination reaction and literature investigation,we speculated that cobalt catalysts,especially Cp~*Co(?),are extremely advantageous for the construction of C-N bonds.In this paper,we synthesized N-pyrimidine indoline compounds as substrates,using dioxazolone as the amination reagent,under the catalysis of Cp~*Co(?),31 compounds of 7-amidoindoline were synthesized by activating the C-H bond at the C7-position of indoline.At the same time,both N-methyl-N-(pyrimidin-2-yl)aniline and N-pyrimidinecarbazole can be realized the amination of C-H bond under this system.The method requires no additives,and the reaction is carried out under air conditions.It has the characteristics of simple operation,good substrate applicability,and the the yield up to 99%.The reaction mechanism was explored through H/D exchange experiment,kinetic isotope effect experiment and free radical trapping experiment,and a possible reaction mechanism was proposed.A series of derivatization experiments have proved the application potential of this reaction.In addition,a series of derivatization experiments had been conducted,such as gram-scale reaction,removing diecting group,dehydrogenation-oxidation to indole derivatives,which further demonstrated the potential application of this reaction in organic synthesis.