Studies Of Synthetic Strategy Based On The Nucleophilic And Electrophilic Ambiphilic Properties Of Triflone Analogues

Sulfones synthon have been widely applied in organic synthesis for the construction C-C bonds,C-O bonds and C-X bonds due to their ambiphilic characteristics as nucleophiles and electrophiles.As one member of sulfones,although the triflones are amphoteric reagents similar to general sulfones,they are different from general sulfone owing to containing a strong electron-withdrawing group（-SO₂CF₃）.This dissertation is focused on developing new methodologies for synthesizing fluorinated alkenes and arenes starting from alkyl triflones based on the ambiphilic properties of triflones,and four results were obtained as follows:Part Ⅰ:Highly efficient synthesis of gem-difluoroalkenes from readily available alkyl triflones and difluorocarbene precursors such as TMSCF₂Br has been achieved（22-95%yields）.The reaction,regardless of electronic effect,gives gem-difluoroalkenes in good to excellent yields.The mechanism may involve tandem deprotonation of triflones,nucleophilic addition,and the elimination of SO₂CF₃.Part Ⅱ:A widely applicable approach for synthesizing Z-monofluoroalkenes from readily available alkyl triflones and NFSI has been developed（52-92%yields,Z/E≥95/5）.The reaction proceeded under mild conditions,affording mono-fluorinated alkenes in good to excellent yields with excellent chemo-regio-and stereoselectivity.The mechanism may involve electrophilic fluorination of triflones and a following highly stereoselective concerted bimolecular elimination（E2）of CF₃SO₂H.Part Ⅲ:A versatile synthesis of[¹⁸F]Ar-CF₃and Ar CF₂Nu type compounds from readily available reagent Ar CF₂SO₂CF₃ has been developed（42-99%yields,28-93%radio chemical yields）.Various nucleophiles,including weak nucleophiles such as halides(¹⁸F^-,Cl^-,Br^-,I^-),RSH,ROH,could react with Ar CF₂SO₂CF₃ efficiently to give corresponding difluoromethylene products.The reaction provides an effective synthetic methdology to hard-to-reach Ar CF₂X and important[¹⁸F]Ar-CF₃.Moreover,the control experiments and study of the Hammett plot indicated that the reaction might go through a difluorocarbocation intermediate（S_N1 process）via steric hindrance-assisted cleavage of the trifluoromethylsulfonyl group.Part Ⅳ:A facile method for synthesis of sodium aryldifluoromethyl sulfinates（Ar CF₂SO₂Na）via Na BH₄reduction of readily available aryldifluoromethyltriflones in excellent yields under mild conditions has been developed（92-95%yields）.The obtained sodium aryldifluoromethyl sulfinates are excellent radical precursors.Furthermore,the sodium aryldifluoromethyl sulfinates have been used successfully in photocatalyzed radical addition-cyclizations and Minisci type reactions（42-88%yields）.The advantages of the reactions include mild reaction conditions,easy work-up,and environment-friendliness.