Direct Synthesis Of N-arylindoles Via The Cascade Reactions Of Allenic Ketones With Indoles

Indole is one of the most common heterocyclic compounds in nature.Among them,N-arylindoles are attractive molecules as they are not only privileged structural motifs in natural products,pharmaceuticals,and functional organic materials,but also the most widely applied precursors in organic synthesis,due to its unique structure and properties.As an important bioactive group,they have attracted great attention of synthetic chemists.However,it has been reported that the synthesis route often needs to be catalyzed by noble metal complexes with complex structure,difficult to obtain and high cost,which is prone to bring about environmental pollution and metal residue.Therefore,the development of a simple,economical,green and efficient method for the synthesis of N-arylindole derivatives is of great significance for the research and development of new drugs and bioactive molecules.In continuation of our interest in indole and allene chemistry,this thesis mainly studies the novel method for the synthesis of various N-arylindole derivatives by the multi-component cascade reaction of indoles and allenic ketones.In this study,the multi-component tandem cyclization reaction has been developed using cheap and readily available allenic dienone and indoles as the substrates under the promotion of Cs₂CO₃.We constructed functional benzene with high selectivity and atomic economy,and realized the efficient synthesis of a series of N-arylindoles.This novel study enable facile construction of N-arylindoles from easily obtainable acyclic units with high atom economy.This reaction not only makes indoles strongly tolerant to various functional groups,but also applies to N-H-pyrrole derivatives.It is noteworthy that this method does not require addition of transition metals,has the advantages of atom and step economy,high regional selectivity,simple and readily available starting materials and wide scope of substrates.Thus,the methodology developed herein is expected to find wide applications in the field of organic synthesis.