Study On Construction Of Organic Selenium Compounds By Multicomponent Reaction Involving Selenium Powder/Diselenides

Organic selenium compounds are a kind of widely studied organic reagents,which can be introduced into organic molecules in the form of electrophiles,nucleophiles or free radicals.They have different application prospects in various biological processes.In recent years,the design reaction using diselenides or selenium powder as selenium source has become a powerful tool for researchers to construct complex organic selenium compounds,and many novel selenium containing heterocyclic compounds have been synthesized through rational design of substrate structure.This paper is mainly devoted to the study of synthetic methodology of organic selenium compounds.It explores the new three-component series reaction involving aromatic o-diamines,isonitrile and selenium powder catalyzed by monovalent copper salt,as well as the rapid decarboxylation of alkynic acid by N-fluorobenzenesulfonamide（NFSI）and diselenide,which provides novel,simple and green synthesis methods for nitrogen-selenium-containing heterocycles and selenium substituted selenamines,respectively.It further enriched the reaction types involved in elemental selenium and diselenide.In the first part,the research progress in the synthesis of organic selenium compounds such as mono-selenium compounds,di-selenium compounds and selenium containing heterocycles using elemental selenium as selenium source is reviewed.And the research progress of C-H bond selenidation with diselenides in recent years is also reviewed,which focuses on the C-H bond selenidation under different reaction conditions such as copper catalysis,other transition metal catalysis and photocatalysis.In the second part,a new method has been developed for the synthesis of benzimidazole[2,3-c][1,2,4]selenodiazole-3-imine compounds by a three component tandem reaction involving aromatic o-diamines,isonitriles and selenium powder.A series of benzimidazole[2,3-c][1,2,4]selenodiazole-3-imine compounds have been synthesized in 65-92%yields by using isocyanide with multiple transformation sites as the nitrogen source,selenium powder with cheap,easy to obtain,stable and low toxicity as the selenium source,10 mol%Cu I as the catalyst and 1 equiv of Cs₂CO₃as the base in 1,4-dioxane at 80℃for 10 h.The method employs green copper/air as the catalytic system and goes through a radical tandem cyclization process,constructing one N-Se bond,one C-Se bond and three C-N bonds in one step.The simple availability of the starting material,high yield,high atom economy（water being the only byproduct）,and simplicity of operation are the features of this reaction and it provides an efficient,facile,and green route for the synthesis of benzimidazoloselenediazole compounds.The target compounds were tested by MTT assay to inhibit the proliferation of MGC-803（human gastric cancer cells）,T24（human bladder cancer cells）,A549（human lung cancer cells）and Hep G2（human liver cancer cells）four cancer cell lines in vitro.The results revealed that the target compounds showed potential anticancer activities with in-depth research values.In the third part,a new method for the synthesis of polyseleno-substituted enamines using diselenide as selenium source was developed.A series of polyseleno-substituted enamine derivatives were synthesized in 48-93%yields from simple and readily available alkynyl carboxylic acids,NFSI（N-fluorobenzenesulfonamide）and diselenide,which were reacted in1,4-dioxane for 30 min under catalyst-free room-temperature conditions.The rapid decarboxylative tri-or tetrafunctionalization of alkynyl carboxylic acids under catalyst-free room-temperature conditions has been realized by the combination of NFSI with diselenides,which employs NFSI not only as a useful oxidant but also as an efficient amination reagent with two or three C-Se with one C-N bond constructed in one step.Diselenides participated in the reaction in the form of positive selenium ion.This reaction offers an novel and facile,and green route to polyseleno-substituted enamines.