Synthesis Of Isobenzopyran Compounds By Radical Cyclization And Tandem Coupling Reaction

Isobenzopyran is important pharmacophore presented in biologically active molecules and natural products.At present,some synthesis of isobenzopyran compounds often required the use of the metal catalysts,which are costly and cannot be reused.They do not meet the requirements of atomic economy.The transition metal impurities need to be further separated during the post-treatment process.There are also certain problems in terms of aspects.There are many methods involving regioselective synthesis.Although the reaction has good selectivity under many conditions,some isomers are still generated,which may affect the experimental results or subsequent experiments.This thesis is based on the previous research on the synthesis of benzofuran compounds in our group.The metal-free-catalyzed radical cyclization tandem coupling reaction,induced by LiHMDS,uses 2-iodo benzyl allenyl ethers and imines as the substrate,in order to synthesize a series of isobenzopyran compounds.This thesis consists of three chapters.The first chapter briefly described the biological activity of isobenzopyran compounds,and the research progress on the synthesis of isobenzopyran compounds.On this basis,the research topics of this thesis were put forward.In the second chapter,the synthesis method of isobenzopyran was studied.The addition of a base converted the imine to a 2-azaallylanion,followed by single electron transfer(SET)with 2-iodo benzyl propadienyl ether.SET initiated radical-radical cyclization,and then an intermolecular radical-radical coupling reaction was used to synthesize isobenzopyran compounds.By screening the reaction conditions such as the base,the solvent,the temperature,and the concentration used in the reaction,a cost-effective synthesis condition was finally determined.Afterwards,the applicability of this new synthesis method was studied.22 different substituted types of isobenzopyran compounds were synthesized by using different imine substrates and 2-iodobenzylpropadienyl ether.And the subsequent synthesis of polycyclic isobenzopyransThe third chapter was the experimental part,which mainly included the synthetic experimental operation steps and spectral data of related compounds in the thesis.