Studies On The Synthesis Of Polysubstituted Quinolines Based On Copper-catalyzed Tandem Reaction Of Alkynyl Imines With Diazo Compounds

Quinoline derivatives are one of the most important heterocyclic compounds,which exist widely in nature and reveal numerous biological activities such as antimalarial,antitumor,anti-inflammatory,antimicrobial activities etc.Therefore,the synthesis of quinoline molecule in an efficient manner has already become the research hotspot in the field of organic synthesis.Plenty of classical approaches to quinoline molecule have been extensively developed since the 19 th century,such as the Skraup,Doebner-von Miller,Friedlander,Pfitzinger and Conrad-Limpach reactions.Despite these notable advances in this area,some challenges still exist,such as harsh reaction conditions,tedious reaction procedure and the generation of byproducts during the reaction course,which not only pollute the environment but also make it difficult separate the products.In recent years,transition-metal-catalyzed tandem reactions have become a concise and efficient strategy for the construction of structurally complex molecules in organic synthesis.In the course of reaction,multiple chemical bonds are broken and formed only by one “pot”.Accordingly,developing methods for the construction of quinoline derivatives by a transition-metal-catalyzed tandem strategy is significant in organic synthesis.In this paper,an efficient and concise synthesis of quinoline derivatives through copper-catalyzed tandem annulation of alkynyl imines with diazo compounds is described.This transformation involves an in situ formation of allene and intramolecular electrocyclization,which features high efficiency,mild reaction conditions,easy operation,and broad functional-group tolerance.A wide variety of C4-functionalized quinolines were provided in up to 92% yield for 33 examples.