Synthesis Of 2-aryl-3-sulfonyl Substituted Quinolines Through An Electrochemical Pathway

As six-element nitrogen-containing heterocyclic compounds,quinolines are widely used in the field of organic materials,and have outstanding roles in the field of medicine and industry.Quinolines are found in coal,oil,shale oil,and wood,and are also widespread in natural products,especially in alkaloids and drug molecules.The synthesis of quinoline compounds also attracts much attention due to their wide applications.At the same time,as the core skeleton of many natural products and drugs,sulfonyl compounds have received extensive attention for their important biological activities.At present,the preparation of sulfonyl compounds has become an important topic in the academic circle.However,the traditional preparation methods require the harsh conditions of strong acid and strong oxidant,which usually lead to the disadvantages of low regioselectivity and limited substrate range.Therefore,the reaction conditions for synthesizing sulfonyl-substituted quinolines by traditional chemical methods are more severe,which greatly limits the development of sulfonyl-substituted quinolines.Electrochemical synthesis has become an attractive and environmentally friendly organic synthesis method to synthesize chemical compounds instead of traditional chemical oxidizing and reducing agents.The advantage of this method is that precise control of product selectivity can be achieved by adjusting the current and voltage.The electrochemical synthesis reaction conditions are mild,and the need for oxidizing agent and reducing agent,while greatly reducing the occurrence of side reactions.In this paper,a reaction for the synthesis of 2-aryl-3-sulfonyl-substituted quinolines using benzoxazinones as substrate and sulfonyl hydrazide as a sulfonylation reagent under electrochemical catalysis was established,and a new method for the synthesis of quinolines was developed.This method has the advantages of mild reaction conditions and does not require the use of noble metal catalysts or external oxidants,and provides a green and environmentally friendly route for the synthesis of functionalized quinolines with excellent regioselectivity.In addition,the method has good functional group tolerance and a wide range of substrates.The scale-up experiments and subsequent extension experiments prove the practicality of electrochemical synthesis.which is in line with the characteristics of green environmental protection.In addition,the possible mechanism of the reaction was verified through control experiments and density functional theory calculations.The structures of all the products were characterized by ~1H NMR,¹³C NMR and HRMS,and the structure of products 3aa and 3ha were determined by the single-crystal X-ray diffraction.