Study On Cycloaddition Reaction Involved In Alkynyl Compounds

Unsaturated carbon-carbon triple bonds in alkynyl compounds can participate in various chemical transformations,among which the cycloaddition reaction of alkynyl compounds to construct carboheterocycles has received more and more attention in recent years.Benzynes belong to a special class of reactive intermediates in alkynes and are widely used in the synthesis of carbocycles and heterocycles.Six-membered heterocyclic compounds are widely found in natural products and have major applications in the fields of drugs,materials,and dyes.Nitrogen and oxygen six-membered heterocycles can be efficiently constructed by the Diels-Alder reaction,insertion-cyclization reaction,and multi-component reaction of benzyne,but the method for constructing sulfur-containing six-membered heterocycles by benzyne cyclization is very limitedIn this thesis,using Kobayashi reagent as benzyne precursor reagent,cyclization reaction with thiocarboxylate under mild conditions to get two reaction products of six-membered sulfur-containing heterocycles.This reaction did not require transition metal catalysis,and the two products were also effective selective control could be carried out according to different reaction conditions,and its structure could be confirmed by single crystal.The universality of the substrate was high,and the product yield was 22-80%.In addition,five compounds were selected for gram-level scale-up experiments,and five samples were tested for the basic antibacterial biological activity inhibition zone.The results of the inhibition zone were compared with the existing antifungal and bacterial drugs on the market.Structural-like compounds have certain antifungal effects,and some compounds may also have certain effects on bacteria.Another attempt was made to use active alkynyl esters to construct polysubstituted benzene compounds through [4+2] cycloaddition.As important organic synthesis intermediates,polysubstituted benzene compounds are widely used in the preparation of various natural products.In this work,α-cyano-β-methylalkenyl(hetero)aryl ketones and dialkyl butynedioates were used as substrates to form rings through Diels-Alder reaction,an effective method for construction of polysubstituted benzenes was developed.The reaction did not require transition metal catalysis,and the conditions are mild.Using simple and easy-toobtain alkynoate compounds and cyanoketene derivatives under the promotion of inorganic bases,20 kinds of polysubstituted benzenes were obtained in excellent yields of 62-94%.The structure of the target compound was confirmed by single-crystal confirmatory diffraction,and the reaction could be scaled up on a gram scale with a yield of 90%.This study provides a simple and convenient new method for the generation of polysubstituted benzene compounds.In conclusion,the thesis developed two types of cycloaddition reactions involving different types of alkynyl compounds.6-alkoxyl-6-aryl-6H-benzo[c]thiochromenes,6-alkoxyl-6H-benzo[c]thiochromenes,and polysubstituted benzene compounds were efficiently constructed without transition metal catalysis.The reaction can be scaled up at the gram scale,and the yield remains unchanged.Two new methods are provided for the synthesis of six-membered sulfur-containing heterocycles and polysubstituted benzene derivatives...