Studies On Electrophilic Sulfenylation And Free Radical Sulfonylation Reaction Of Alkene Or Alkyne Derivatives

Recently,studies on the transformation of unsaturated hydrocarbons have attracted more and more attention.As two important classes of heterocyclic skeletons,quinolinones and isoxazoles are widely found in maining natural products and drug molecules,which are usually prepared from alkene or alkyne derivatives.If the sulfenyl group is introduced to the quinolinone and isoxazole,the pharmacological activity and functional properties will be significantly changed;sulfone compounds are also known as an important class of organic sulfur compounds,which have played a unique role in the fields of organic polymer material chemistry and medicinal chemistry.Therefore,how to efficiently introduce sulfonyl group into heterocyclic molecules using easily available and green sulfonyl source is also a big issue.In the first two parts of this thesis,N-thiosuccinimide is used as an electrophilic sulfur reagent to promote the cyclization of alkenyl ketones and alkynyl ketoximes,respectively,to access 3-thioquinolinones and 4-thio isoxazoles.Through the optimization of reaction conditions,the yield of both of these transformations can be up to 90%.Furthermore,a variety of substrates are examined under the optimal conditions,and most of them transformed to3-thioquinoliones or 4-thioisoxazoles in moderate to excellent yields.Finally,the key intermediate sulfenium cations are captured and the reaction mechanisms are further confirmed based on the results of control experiments.In the third part of this thesis,a new kind of sulfone derivatives,??arylhydrazo-?-keto sulfones are prepared efficiently.The sodium sulfinates as green sulfone sources.The?-arylhydrazo-?-keto sulfones are accessed in one pot from simple olefins and aryl boron tetrafluoride diazonium salts.After optimization of conditions,the best conditions are obtained as follows:0.75mmol styrene,0.15 mmol 4-methoxyphenyl boron tetrafluoride diazonium salt,0.3 mmol p-toluene sulfinate sodium,0.03 mmol of CuSO₄·5H₂O,and 1.5 mL of N,N-dimethylacetamide as the solvent,at room temperature for 6-10 hours.The yield of the desired product can be up to 80%.Under the optimal conditions,the substrate scope is extended and most of them can be produced in satisfying yields.Finally,the reaction mechanism is investigated carefully,and synthetic application is demonstrated to be useful through the conversion of cinnoline heterocycles from the desired products.The corresponding products are characterized by HRMS?¹H NMR and ¹³C NMR.The structures of some products are further confirmed by X-ray single crystal diffraction.The synthetic methods for sulfenyl heterocycles are relatively simple to operate,which provide a new alternative for the synthesis of sulfur-containingheterocycles.Theefficientpreparationof?-arylhydrazo-?-keto sulfones is directly from three simple substrates,sulfinates,alkenes and diazonium salts,which is not only step-economic process,but also fulfills the requirements of green chemistry.