Cyclization Of Alkyne For The Synthesis Of Nitrogen-containing Heterocyclic Compounds

Nitrogen-containing heterocyclic compounds are widely found in natural products and pharmacologically active molecules.They are widely used in medicines,pesticides,fine chemicals and dyes due to their high physiological activity.Isoquinoline and furoxane,having high biological activity,are the basic skeleton of many drugs.In addition,isoquinoline derivatives are also used as ligands in most transformation.Thus,the development of a simple,environmentally friendly,and efficient method for synthesizing such compounds is highly desirable.Alkynes,with an unsaturated C≡C bonds,can undergo addition reactions,oxidation reactions,polymerization reactions,etc.Addition of organic molecules to unsaturated bonds increases the diversity of the molecules.The cyclization of alkynes has been widely used in the synthesis of cyclic compounds due to its high atom utilization and chemical selectivity,which has important research values and broad development prospects.This paper introduces the participation of alkynes in the construction of nitrogen-containing heterocyclic compounds and mainly includes the following:（1）The first chapter introduces the synthesis methods of several common nitrogen-containing heterocyclic compounds in recent years,including indole,pyrrole,pyridine,isoquinoline,and cyclic nitrogen oxides.This article mainly describes the cyclization reaction by using cheap and easily available alkynes as raw materials to construct the corresponding nitrogen heterocycles.（2）In the second chapter,a[4+2]cyclization of 3-phenyl-4-sulfonyl-4,5-dihydro-isoxazole and internal alkynes to synthesize polysubstituted isoquinolines by using[（Cp*RhCl₂）₂]and AgSbF₆ synergistic catalysis was described.The reaction substrate has a wide range,and various substituted arylalkynes or alkylalkynes can react with isoxazole to obtain the target product in moderate to good yields.This method provides a simple and efficient new way for isoquinoline synthesis.（3）In the third chapter,a MnO₂-catalyzed[2+2+1]tandem cyclization reactions of terminal alkynes,tert-butyl nitrite and sodium sulfinate for the synthesis of furoxans was achieved.In this transformation,cheap and easily available tert-butyl nitrite provides a nitrogen source.Three chemical bonds,namely C-S,C-N,and N-O bond,were constructed through a one-step reaction,and the range of substrates is wide.In addition,menthol modified arylacetylene can also carry out the reaction smoothly.