Studies On The Synthesis Of Nitrogen-containing Monocyclic Rings And Indole/Indolinone-derived Fused Azacycles

N-heterocycles are widespread in nucleic acids,proteins,natural products,and synthetic bioactive molecules,which exhibited significant utilization in human society.Thus,the development of simple,rapid and efficient synthetic access to various N-heterocycles has always been the interests of organic chemists.In this thesis,a series of N-heterocycles were synthesized from simple and readily available raw materials by Neber rearrangement,cycloaddition,aerobic oxidative dearomatization-cycloaddition-rearrangement cascade reaction and Diels-Alder reactions.The specific contents are devided into four parts as followed:Firstly,a one-pot metal-free Et₃N-mediated Neber reaction of aryl/alkyl-2,2,2-trifluoroethylketoximes has been developed in the presence of methanesulfonyl in DCM,which enables the facile construction of an array of trifluoromethyl-substituted azirines in up to 92%yield.The reaction is easy to manipulate,react under mild reaction conditions and can be scaled up to gram scale with well-maintained yield.In addition,the azirines can be efficiently transformed to CF₃-containing amino-alcohol,amino ketone and trisubstituted pyrrole derivatives.Secondly,we break the traditional[3+2]cycloaddition type of diazomethyl phosphate and realize a new[3+3]cycloaddition of it with glycine ester imine in the presence of cesium carbonate and silver catalyst,affording a series of phosphate substituted tetrahydrotriazines in 28-75%yields with 80:20 to>99:1diasteroselectivities and single regioselectivities.In the third section,by using enamides as dinucleophilic reagent,a one-pot aerobic oxidative dearomatization-cycloaddition-rearrangement cascade reaction of2-aryl-1H-indoles was realized under cobalt catalysis,furnishing a series of fused tricyclic N-heterocycles in up to 94%yield and 68:32 to 86:14 diastereoselectivities.The reaction was able to be amplified to gram scale in 91%yield.Further transformation of obtained product to biologically active substances1H-pyrrol-2(3H)-one derivative and alkenyl substituted indole-3-one derivative was also demonstrated.Mechanistic experiments showed that the oxidation process of the reaction may go through a radical process.What's more,we prepared the key indole-3-one intermediate,and successfully realized its cascade reaction with enamides in high efficiency to provide the final product.Finally,a new diene 1-aryl-1-acetamido-1,3-butadiene was disclosed and a phosphoric acid-catalyzed Diels-Alder reaction of it with 2-phenyl-3H-indole-3-one was developed,produced a series of nitrogen-containing tricyclic compounds in 68-76%yields and>95:5 diastereoselectivities.Furthermore,by employing chiral phosphoric acids derived from BINOL as catalysts,the tricyclic N-heterocycle can be generated in high yield,diastereoselectivity and enantioselectivity.