Selective Oxidation Of Diaryl Thioether Catalyzed By A Tridentate Schiff Base-VO?acac?₂ System

The cross coupling reaction of the C-S bond has been extensively studied by organic chemists.A variety of bioactive diaryl thioether have been widely used as therapeutic drugs in the chemical synthesis of drugs,which resulted in the detail study of diaryl thioether being of great practical significance in the field of medicinal chemistry.It has been known that thioether is easily oxidized to sulfone or sulfoxide.As practical intermediates,sulfoxide and sulfone have been applied in the preparation of fine chemicals and in the synthesis of bioactive compounds.With this in research background,a series of fluorinated and carboxyl substituted diaryl thioether compounds were synthesized and characterized for the substrates of catalytic oxidation.The tridentate{N,O,S}Schiff base-VO?acac?₂ catalytic system was set up for the optimized experiments of the thioether selective oxidation.The specific plan is as follows:18corresponding thioether compounds were prepared by the reaction of fluoro or carboxyl substituted iodobenzene and aryl mercaptan,employing CuI as the catalyst and PEG₂₀₀as the phase transfer reagent.All thioether compounds were characterized by nuclear magnetic resonance?NMR?spectroscopy,of which molecular structures of part compounds were established by single crystal X-ray diffraction.Tridentate{N,O,S}Schiff-base ligands were synthesized to explore the catalytic oxidation of thioether under the catalytic systems of tridentate Schiff-bases,VO?acac?₂ and 30%H₂O₂.The conversion and chemical selectivity of the catalytic system for the thioether oxidation were investigated.Catalytic oxidation mechanism was speculated.