Copper(Ⅱ)-catalyzed Tandem Cyclization Reaction Of Ortho-substituted Aryl Isothiocyanate And DMF

In organic chemistry,nitrogenous heterocycles are an important component.It occupies an important position in the field of modern medicine,natural products and pesticide synthesis.Therefore,it is of great significance to develop green and efficient methods for the construction of such substances.It has also been the goal pursued by many chemists at home and abroad.In recent years,transition metal-catalyzed tandem cyclization reactions have outstanding advantages as an effective method for the synthesis of nitrogen-containing heterocyclic compounds.This method can avoid the separation and purification of intermediates,simplify the operation steps,have high bonding efficiency,and realize the construction of multiple covalent bonds in one step,which is conducive to realizing the diversity and complexity of the molecular skeleton.The compound N,N-dimethylformamide(DMF)has good solubility,low price,and other properties,and is often used as a solvent in organic reactions,but because of its simple structure and chemical properties,it can also be used as a substrate to participate in the reaction.In recent years,the study of organic synthesis reactions using DMF as a reaction substrate has occupied an increasingly high position in the study of organic synthetic chemistry.Based on the outstanding advantages of tandem cyclization,this dissertation developed a new method for constructing nitrogencontaining heterocycles based on DMF in tandem cyclization reactions of o-alkynyl aryl isothiocyanate and o-iodoaryl isothiocyanate.Specifically,it is divided into the following two parts:In the first part,we developed a new method to construct a tandem cyclization reaction with inexpensive metal copper as catalyst,potassium thiosulfate as additive,DMF and o-alynyl aryl isothiocyanate as reaction substrates to construct a substitute benzothiazide.During this reaction,the complexity and diversity of molecules can be easily introduced.The reaction substrate exhibited excellent functional group compatibility and reactivity,and successfully constructed dimethylamine-substituted benzothiazide compounds with excellent yields.In the second part,we also developed a tandem cyclization reaction with cheap metal copper as catalyst,potassium persulfate as an additive,DMF and o-iodophenyl isothiocyanate as the reaction substrate,and constructed a series of new methods for dimethylaminobenzothiazole compounds simply and effectively.In this catalytic system,both C-N bonds and C-S bonds are constructed in one step.The compatibility of the reaction substrate is good,and the mechanism is proved by the experimental findings,indicating that the experiment does not follow the free radical mechanism.The biggest advantage of this method is that cheap metal copper is used as catalyst and potassium thiosulfate is used as an additive,which provides a new method for the preparation of dimethylaminobenzothiazole compounds.