Research On A New Method Of Synthesizing Nitrogen And Oxygen Heterocyclic Compounds Through Radical Addition Tandem Cyclization

In recent years,radical addition on the alkenes and alkynes cyclization synthesis of heterocyclic compounds,it has attracted much attention from scientists.This idea provided a good way to construct new C-C bonds and carbon-heteroatom bonds.A variety of functionalized products can be obtained by the addition of radical to the alkenes and alkynes,such as trifluoromethylation,sulfonylation,alkylation,cyanation,and so on.In this dissertation,we have described the various types of radical addition with alkenes and alkynes cyclization synthesis of different heterocyclic compounds.Three different methods for synthesizing heterocyclic compounds have been developed by radical cyclization reactions.The main contents of this thesis include the following three parts:1.Cyanomethylation and cyclization of aryl alkynoates with acetonitrile synthesis of 3-cyanomethylated coumarins.Cyanomethylated coumarins were synthesized via cyanomethylation and cyclization of aryl alkynoates using cheap and available reagent acetonitrile as the cyanomethyl source in the presence of TBPB(tert-butyl peroxybenzoate)under transition-metal-free conditions.For the substrates with various substituents on benzene ring,the reaction proceeded smoothly to give the corresponding products in moderate to good yields.The resulting products could be simply converted into some other related coumarin derivatives.2.Radical cascade cyclization reaction to assemble phenanthridines from N-arylacrylamide under photoredox catalysis.A radical addition/nitrile insertion/hemolytic aromatic substitution(HAS)cascade reaction to prepare 6-quaternary alkylated phenanthridines was developed.The addition of the active methylene radicals which were generated from 2-bromoacetonitrile,ethyl 2-bromoacetate,2-bromo-N,N-dimethylacetamide,or 2-bromo-l-phenylethan-l-one to carbon-carbon double bonds of N-arylacrylamides followed by the cyano-participating sequential cyclization produced a series of phenanthridines in moderate to good yields under photoredox catalysis.3.Visible-light-mediated decarboxylative alkylation cascade cyano insertion/cyclization of N-arylacrylamides.The visible-light-mediated decarboxylative functionalization of aliphatic carboxylic acids using organocatalysts has rarely been reported.This study represented an environmentally benign decarboxylation method involving the combination of eosinY and(NH4)2S2O8.This system converted aliphatic carboxylic acids to alkyl radicals,followed by their addition to the carbon-carbon double bond of the Narylacrylamide cascade cyano insertion/cyclization to construct alkylated phenanthridines in moderate to good yields under photoredox catalysis.