Study On Synthesis Of Selenium-containing Five-membered Heterocyclic Compounds Based On I₂ Catalyzed Tandem Cyclization Of Elemental Selenium

Selenium-containing five-membered heterocyclic compounds,especially benzoselenazole and benzoselenophene,are an important class of organic selenides,and their unique skeletons are widely found in natural products,drug molecules and functional materials.Chemists such as Bayoumy have confirmed that certain organic selenium-containing compounds have stronger biological activity,better biocompatibility,and lower toxicity than natural selenium-containing compounds.Based on the potential application value and broad development prospects of benzoselenazole and benzoselenophene derivatives in pharmacy and functional materials,so looking for efficient and simple synthetic methods to construct benzoselenazole and benzoselenophene compounds have always been a hot spot of concern for chemical researchers.In this paper,based on the overview and analysis of recent research progress of benzoselenazole and benzoselenophene derivatives,a method with simple and easily available raw material and mild reaction conditions was developed to efficiently synthesize benzoselenazole and benzoselenophene compounds.The research content of this thesis mainly includes three chapters:Chapter one:The recent progresses in synthesis of selenium-containing five-membered heterocyclic compounds benzoselazoles and benzoselenophenes were summarized.Chapter two:Using simple and readily available 2-naphthylamine/1-naphthylamine,substituted formaldehyde and selenium powder can generate 2-arylbenzoselenazole compounds through the series cyclization reaction under metal-free conditions.The present approach has the advantage of the use three-component"one-pot method",uses inexpensive,easily available,low-toxic and stable selenium powder as the selenium source,and building the C-N/C-Se bond through the free radical strategy for the one-step synthesis of 2-arylbenzoselenazoleChapter three:In the absence of metal catalysts,2-phenylbenzo[b]selenopheno[3,2-d]selenophene and 2-phenylbenzo[4,5]selenopheno[2,3-b]thiophene were synthesized from 1,3-disubstituted-1-butene and2,4-diphenylthiophene by radical cascade cyclization with selenium powder,respectively.This reaction developed a new route for the synthesis of benzoselenoselenophenes and benzoselenothiophenes through C(sp~3)-H functionalization and multiple constructions of C-Se bonds.