Study On The Development Of Novel Methods For The Preparation Of Two Classes Of Fused Nitrogen-containing Heterocycles

Fused nitrogen-containing heterocycles not only constitute the essential unit of numerous natural products,but also demonstrate significant and diverse bioactivities.Therefore,the development of novel methods for the preparation of fused N-containing heterocycles is an important task in both synthetic and medicinal chemistry.Meanwhile,one-pot multi-component cascade reaction has become one of the most effective strategies in building N-containing heterocyclic frameworks due to its remarkable advantages such as atom-economy,environmental benignancy and operational simplicity.Inspired by the above facts,some highly efficient and novel synthetic approaches toward pyrido[2',1':2,3]imidazo[4,5-c][1,2,3]triazolo[1,5-a]quinolines and 3-acylquinolines via one-pot cascade reactions have been established in this thesis.The main results are summarized in the following two parts:Firstly,an efficient synthesis of pyrido[2',1':2,3]imidazo[4,5-c][1,2,3]triazolo[1,5-a]quinolines through a one-pot bimetallic relay catalyzed cascade reaction of 2-?2-bromophenyl?imidazo[1,2-a]pyridines,alkynes and sodium azide is developed.Mechanistically,the formation of the title compounds involves firstly a Cu-catalyzed Click reaction and C–N coupling of the substrates to give the key intermediate2-?2-?4-phenyl-1H-1,2,3-triazol-1-yl?phenyl?imidazo[1,2-a]pyridine followed by its Pd-catalyzed intramolecular cross dehydrogenative coupling.Compared with literature methods,this new protocol shows advantages such as simple operation process,high efficiency,and broad substrate scope.Secondly,an efficient synthesis of 3-acylquinolines via the one-pot cascade reaction of saturated ketones with 2-aminoaryl carbonyl compounds under the promotion of Cu?OAc?₂/bpy/TEMPO is developed.Mechanistically,the formation of the title compounds involves a cascade procedure including C?SP³?–H bond amination,enaminone formation,and enamine-carbonyl condensation.Compared with literature methods,this new protocol shows advantages such as cheap substrates,mild reaction conditions,and good tolerance of functional groups.