Study On Synthesis Of Organosulfur/Selenium Compounds Employing Thios/Selenium Sulfonates Under Nickel Or Light Conditions

Organic sulfur compounds are widely found in natural products and pharmaceutical molecules.In recent years,the development of new strategies to construct C-S bonds has attracted widespread attention from chemists.Organic chemists have developed different sulfur reagents to constract the C-S bonds.These sulfur reagents have found widespread application in synthesis of pesticides,drugs,and polymers.Traditional sulfur reagents face three main challenges:(1)With unpleasant odors;(2)Not easy to be prepared and less variety;(3)Unstable to air and not easy to store;(4)Relatively toxic.Some new sulfur reagents have been synthesized and used in the synthesis of organic sulfur compounds.As a new sulfur reagent,thiosulfonate has some advantages such as without unpleasant odors and easy to be prepared.They are easily handled liquids or solids,which generally show a low to moderate toxicity.They can be used as not only sulfenyl reagents but also sulfone reagents.Selenosulfonate has similar characteristics,so we will study together.This paper mainly focuses on the development of a series of reactions with thios/selenium sulfonates to construct C-S or C-Se bonds,and has been successfully used in the synthesis of various structural compounds.This paper mainly consists of the following three parts:In the first part,a nickel-catalyzed defluorinative reductive cross-coupling ofgem-difluoroalkenes with thiosulfonate or selenosulfonates is described.The reaction involves the formation of thiolated or selenylated monofluoroolefins via regio-selective C-F bond cleavage and C-S or C-Se bond formation and features easily available substrates,mild reaction conditions and high E-selectivity.Some substrates can also achieve reduced cross-coupling in high yields under conditions without ligands.Through this strategy,not only the selective construction of C-S bonds,but also the selective construction of C-Se bonds can be achieved.This reaction broadens the application range for the synthesis of monofluoroolefin derivatives.Moreover,one of the derivatives by further cross coupling with PhMgBr exhibited aggregation induced emission(AIE)enhancementeffect.In the second part,a nickel-catalyzed ring opening and subsequently reductive cross-coupling of cycloketone oxime esters with thiosulfonate or seleniumsulfonate is reported.C-C bond cleavage and C(sp3)-S or C(sp3)-Se bond formation have been achieved through the strategy of Ni-catalyzed reduction coupling.A new strategy was provided for the synthesis of thioether compounds containing cyano groups.Through mechanism experiments,we postulated that a radical mechanism was involved,and more detailed mechanistic studies are being undertaken.The reaction is amenable to scaleup with lower catalyst loading,which has broad industrial application prospects.In the third part,a visible-light-promoted cross-coupling of 4-alky 1-1,4 dihydropyridines with thios/selenium sulfonate was studied.A novel synthetic route is provided for the construction of C(sp3)-S bond or C(sp3)-Se bond under metal-free condition wiout oxidant or base.4-alkyl-substituted tetrahydropyridine can be easily prepared from aldehyde in one step and easy to store.By reacting it with thiosulfonate,a series of sulfur(selenium)ether can be efficiently prepared.The reaction conditions are mild and the functional groups are well tolerated.In addition,a series of thioether or selenoether monosaccharide compounds can be efficiently synthesized by this strategy.It is worth mentioning that sulfoxides can be obtained with highe yields via a facile variation of the atmosphere under photocatalyzed conditions.