Studies On The Construction Of Nitrogen-Containing Heterocycles By Free Radical Cascade Cyclization

Nitrogen-containing heterocyclic compounds play very important roles in natural products,pharmaceuticals,photochemistry,electroch emistry,and materials science.In recent years,with the developmen t of modern organic synthesis,the resurgence of reliable and contro llable radical chemistry,radical cascade cyclization reactions have al so received increasing attention.The cascade bicyclization reactions involving nitrogen-centered radicals can be used to rapidly construct nitrogen heterocycles due to their high functional group compatibilit y,bonding efficiency,and atom utilization.This thesis describes the research on the construction of substituted benzo[h]naphthalene[1,8bc][1,6]naphthyridines by free radical bicyclization involving nitrogen-c entered radicals.This thesis is mainly divided into two aspects in the following:1.Summarized the research progress of the double cyclization reaction involving nitrogen-centered radicals to construct nitrogen-containing heterocycles in recent years,based on the following four types of reaction systems:(1)Metal-promoted bicyclization reactions of nitrogen-centered radicals;(2)Metal-free-involved bicyclization reactions of nitrogen-centered radicals;(3)Photo-catalyzed bicyclization reaction of nitrogen-centered radical;(4)Electro-promoted bicyclization reaction of nitrogen-centered radical.2.Introduced the free radical bicyclization reaction of N-(2-cyanophenyl)-N-methyl-2-(1-naphthyl)acrylamide and dicumyl peroxide(DCP)in detail.The reaction using dicumyl peroxide as the methyl source,utilizes cascade cyclization strategy to realize the C(sp~3)-C(sp~3)bond,C(sp~3)-C(sp~2)bond and C(sp~3)-N bond in one step,and synthesizes the benzonaphthyridine nitrogen-containing polyheterocycles.The reaction not only have good functional group compatibility,but also the system is simple.In addition,the conversion can be completed by heating in a solvent.Mechanistic studies show that the transformation is a free radical process,which may include the addition of methyl radicals to carbon-carbon double bonds,the cyclization of alkyl radicals and cyano groups,and the cyclization steps of imine radicals and naphthalene rings.