Study On The Cyclization Reaction Of Acid/Base-Co-Catalyzed Ketone With O-aminobenzylamine

Quinolines are a kind of heterocyclic aromatic nitrogen compound with a double-ring structure.Its skeleton is widely found in alkaloids and natural products.It has antiviral,antitumor,antibacterial,antimalarial and other medicinal chemical and biological activities.In addition,quinoline and its fused quinoline are effective intermediates in organic synthesis and widely used in the synthesis of biocides,dyes,rubber chemicals,corrosion inhibitors and other substances.As a result,the preparation of quinoline compounds and the application of various properties are of continuing interest.There are various methods to prepare the quinolone compound.The methods of Friendl?nder annulation is considered to be the most straightforward methods to develop quinoline derivatives.However,the unstable 2-aminobenzaldehyde used in this synthesis method is unstable,and the self-aldol condensation of the 2-aminoaryl carbonyls has affected the reaction efficiency.Therefore,many effective methods for the synthesis of quinoline rings have widely been reported by several groups.However,these reactions have limitations such as poor functional group tolerance and transition metal as catalyst.In a result,a simple and efficient method,for the synthesis of quinoline derivatives without excessive metal catalysis,is highly desirable.In this paper,we report an acid/base-co-catalyzed intermolecular cyclization of ketones with 2-（amino methyl）anilines using O₂ as the sole oxidant under transition metal-and chemical oxidant-free conditions,and series of quinoline derivatives were prepared by this method.This method has many advantages such as simple operation,mild reaction conditions and wide substrate scope.The reaction not only tolerates a wide range of ketones,but also does not use excessive metals as catalysts in the reaction process,which is in line with the concept of green environmental protection.The experimental results not only provide a simple and effective method for the synthesis of quinoline derivatives,but also provide a new method for the further application of acid-base catalytic systems in the synthesis.