Study On The Synthesis Of Three Types Of Nitrogen-Containing Heterocyclic Compounds Using Chromones As Building Blocks

Nitrogen-containing heterocyclic compounds such as quinolinium salts,4-quinolones and pyridine-2-ones are widely distributed in nature,with rich and diverse structures,as well as physiological and pharmacological activities.They are an important class of heterocyclic compounds and are widely used in various fields.It has attracted people’s attention because it is widely used as a therapeutic drug and plays an irreplaceable role in human production and life.Therefore,finding more efficient methods to synthesize these nitrogen-containing heterocyclic compounds and derivatives is of great significance in the fields of organic chemistry and medicinal chemistry.In this paper,starting from cheap and readily available raw materials,using chromones as building blocks,through a simple and efficient synthesis method,three types of polysubstituted quinolinium salts,4-quinolones and pyridine-2-ones with novel structures and potential pharmacological activities were synthesized.nitrogen-containing heterocyclic compounds.The thesis is divided into three chapters:The first chapter is the review part,which expounds the medicinal value of nitrogen-containing heterocycles and some clinical drugs with nitrogen-containing heterocycles;introduces chromones and some drugs with chromone structure,as well as the use of chromones in applications in organic synthesis.The second chapter developed a simple and efficient one-pot synthesis of chromones with novel structures and potential pharmacological activities,using 3-formyl chromone and N-substituted aniline as raw materials,oxygen in the air as oxidant,and perchloric acid as accelerator.Methods for the synthesis of ketoquinolinium salt compounds.Meanwhile,quinolinium salts are often used as synthons to synthesize other heterocyclic compounds due to their chemical activity.Therefore,we further expanded its application on the basis of synthesizing quinolinium salts,and found that quinolinium salts can be further converted into 4-quinolone under hydrolysis conditions.Further research found that 3-formyl chromone and N-substituted aniline can be directly synthesized by a one-pot two-step method to obtain 4-quinolone without isolating the intermediate product quinolinium salt.Both methods have the advantages of high yield,simple filtration and washing,and no need for traditional purification methods such as column chromatography.A total of 28 polysubstituted quinolinium salts and 20 4-quinolone compounds were constructed.The third chapter introduced that 3-cyanochromone and ethyl 2-pyridine acetate were used as raw materials,and Cs₂CO₃ was used as a catalyst to react in the ionic liquid[BMIM]PF6 to obtain novel chromonopyridin-2-one compounds.Twenty-four compounds were constructed.This method has higher yield and milder reaction conditions,and at the same time,the post-processing only requires filtration and washing as required,no need for column purification.To sum up,in this paper,two types of chromone and fused heterocyclic compounds were obtained by using chromone as a building block,using simple and readily available raw materials,and through simple synthesis steps,and at the same time,quinolinium salts were obtained by derivatization.Multi-substituted 4-quinolone derivatives.The obtained target compounds were all determined by X-Ray single crystal diffraction to represent the single crystal of the compound,and were characterized by ¹HNMR,¹³CNMR,IR,HRMS and other spectroscopic methods to confirm the structure of the compound.