Study On The Electrochemical Cascade Cyclization Reaction Of Nitrosobenzene

The nitrogen-oxygen double bonds of nitroso compounds(R-N=O)are both nucleophilic and electrophilic.In the past few decades,due to the characteristics of nitroso compounds,they have been widely used in synthetic chemistry,especially in the synthesis of nitrogen-containing heterocycles by cycloaddition reactions.For example,the reported conversion of nitroso compounds mainly focuses on nitroso-ene reactions,Diels-Alder reactions,Aldol reactions,metal catalysis,and metal-free catalysis.In recent years,the use of electrochemistry has been considered as a’green’sustainable alternative to traditional toxic redox methods.Nitroso compounds can be reduced and oxidized under electrochemical conditions,and theoretically have various reactivity.However,the electrochemical conversion of nitroso compounds has rarely been reported.Based on this,this paper intends to carry out the free radical cascade cycloaddition reaction of nitrosobenzene under electrochemical conditions to construct a series of nitrogen-containing heterocyclic compounds.In this paper,the following four aspects will be described.Chapter 1 is the introduction,which introduces the related background of electrochemical reaction and its application in organic synthesis,especially cyclization reaction.It is mainly summarized that the reactivity of nitroso groups in molecular skeleton under electrochemical conditions,and it is found that the reaction of nitroso groups often involves single-electron process,but the realization of this process and further chemical selective regulation under electrochemical conditions is underdeveloped at present.Therefore,the reactivity of nitroso derivatives with alkynyl derivatives was systematically explored in this paper under electrochemical conditions.From chapter 2 to chapter 4,the cyclization reaction of nitroso aromatic hydrocarbons with alkynes under electrochemical conditions was studied.The main research contents are as follows:(1)Cyclization of nitrosobenzene with dimethyl butynedioate to construct quinoline heterocyclic compounds.An efficient method for constructing quinoline heterocyclic derivatives was found under the condition of constant current of 20 m A electrochemistry.Nitrosoaromatic nitrogen anion[ArNO]·~-was obtained by double-electron reduction of nitroso compounds at the cathode,and then electron-deficient alkynes were cyclized in series It has good tolerance to aromatic nitrosobenzene compounds and the yield is as high as 80%.At the same time,this method can be applied to the amplification gram-scale synthesis of quinoline heterocycles.(2)Cyclization of nitrosobenzene with ethyl 4-oxo-4-(p-tolyl)but-2-ynoate to construct pyrrole heterocyclic compoundsThe radical anion[ArNO]·~-of nitroso aromatic hydrocarbon was obtained by one-electron reduction of nitroso aromatic hydrocarbon at cathode,and then the pyrrole ring was constructed by radical cascade cyclization of ethyl 4-oxo-4-(p-tolyl)butyl-2-alkynoate at a constant current of 15 m A,with a yield as high as 68%.(3)Ketoamide compounds were obtained by oxidative cleavage of nitrosobenzene and ynones under electrochemical conditions.A reaction of electrochemical synthesis of ketoamide derivatives from nitrosarene and alkynone was found under the condition of constant current of 10 m A in an integrated cell.This reaction involved the oxidative cleavage of the carbon-carbon triple bond of alkynone,and a series of ketoamide compounds were obtained,with the yield as high as 46%.