Synthesis And Application Ofα-Sulfenylated Carbonyl Compounds And Diaryl Sulfides

Organo-sulfur compounds have crucial impacts in life science,medicinal chemistry and functional materials etc..Among them,α-sulfenylated-β-diketones,α-sulfenylated amides/esters,diaryl sulfides are the most important parts of organo-sulfur compounds,which always play vital roles in synthesis of pharmaceuticals,adjusting the oxidation state of chemicals,constituting of drug skeletons.Taking the wide applications of above-mentioned compounds into consideration,the synthetic methodology to which is highly valued in organo-sulfur chemistry.Conventional methods toα-sulfenylated carbonyl compounds usually employ pre-functionalized ketones to interact with thiols,with respect to the preparation of diaryl sulfides,it mainly uses transition-metal-catalyzed cross-coupling as well as pre-functionalization pathways.Recently,the progresses in this domain are chiefly focused on oxidation reactions and transition-metal catalysis.To summarize the known methods,most of them have the drawbacks like long preparation routines,low functional group tolerance,low atom economy etc..In this case,high-efficient pathways to aforementioned compounds are still intriguing for many chemists just like us.During my master study,to develop some new methodologies to organo-sulfur compounds,I carried out the projects as follows:1.New Synthetic Pathway toα-Sulfenylated-β-Diketones Based on Oxidation Relay Chemistry.Employment of KI as the catalyst,O₂ as the terminal oxidant,through oxidation of I^—into trace amount of I₂ to run this reaction,endowing KI oxidation capacity by O₂ oxidation.Various symmetrical/unsymmetricalα-sulfenylated-β-diketones are obtained within our protocol,even for the ones with quaternary carbon centers.Notably,the embellishment of anti-inflammatory drug Butazodine was also realized on gram scales in this case.2.New Synthetic Pathway toα-Sulfenylated Amides/Esters Cascading C-S Bond Formation and C-C Bond Cleavage.On the basis of project 1,inspired by retro-Aldol reactions,we employed 1,3-diketones as the precursors of amides/esters,cascading C-S bond formation and C-C bond cleavage,developed an efficient pathway toα-sulfenylated amides/esters through acidic hydrolysis.We successfully introduced heteroatoms intoα-C-H of amides/esters.The acidic hydrolysis process was confirmed by detailed mechanism study.3.Selective Synthesis of Diaryl Sulfides via Cu（II）Catalysis.We used N,O-contained motifs as the bidentate directing group,Cu（II）as the catalyst,achieved selective sulfenylation of electron-deficient arenes as well as heterocyclic arenes.The Cu（II）coordinated complex was isolated and the structure was unambiguously confirmed by X-ray diffraction,that was the direct evidence to show copper’s participation in C-H activation process.4.Confirmation the Effect of CO Ligand to Pd Complexes’s Chemical Reactivity Through the Interactions Between PhS-SPh and Different Ligands Coordinated Pd Complexes（just selected parts are introduced）We systematically revealed the reason why CO-coordinated Pd complexes were reluctant to undergo carbonylation process,by the usage of crystallography,cyclic voltammetry,chemical conversion as well as DFT studies,the results demonstrated the strong interaction between Pd-C（CO）and the rigid structure of 8-aminoquinoline Pd complexes caused the CO migration insertion barriers.Employing PhS-SPh as the sulfenylating reagent,the chemical reactivities of different ligands coordinated Pd complexes were distinguished.