Studyonthe Asymmertic Insertion Reactionof Sulfur Ylide Catalyzedby Chiral Bronsted Acid

Traditionally,the research on asymmetric insertion reactions has focused on special types of substrates such as diazoesters and diazoketones.They produce metal carbene intermediates under the action of chiral transition metal catalysts,and then bond with carbon-hydrogen,nitrogen-hydrogen bond,oxygen-hydrogen bond,sulfur-hydrogen bond and other reagents.Sulfur ylides can also produce metal carbene intermediates under the action of transition metal catalysts,and then undergo insertion reactions.The relevant research background is reviewed in chapter 1 of this thesis.However,the insertion reaction of sulfur ylidesunder the condition of transition metal free is rarely reported.We envisioned a novel reaction mechanism:using the basicity and nucleophilicity of sulfur ylide,it first reacts with protic acid or other electrophiles to form sulfonium salt intermediates,and then replaces with the corresponding nuclephiles,leaving theby-products of thioethers,through the asymmetric induction of chiral catalysts,it is possible to achieve various types of the asymmetric insertionrssponse to sulfur ylide.Previously,our research group has reported the asymmetric nitrogen-hydrogen bond insertion reaction of sulfur ylide catalyzed by chiral phosphate acid(CPA),which is mainly suitable for aromatic amine nucleophiles.In chapter 2 of this article,our further research shows that when using chiral cyclopentadiene acid catalyst(PCCP),benzylamine nucleophile and sulfur ylide can also undergo asymmetric nitrogen-hydrogen bond insertion reaction.As so far,70%ee value can be obtained,which needs to be further optimized and expanded substrates.In chapter 3 of this article,we studied the asymmetric sulfur-hydrogen bond and oxygen-hydrogen bond insertion reactions of sulfur ylide catalyzed by chiral Bronsted acid.The highest yield is 99%,but the ee value is 0,indicating strong acidic chiral catalysts are unlikely to be suitable for this type of reaction.In chapter 4 of this article,different from the reaction of nitrogen-hydrogen bond insertion through protonation-amination,we tried the electrophilic fluorination-amination reaction of sulfur ylide,trying to generate carbon-nitrogen ang carbon-fluorine bond at the same time enantioselectively,but never succeeded.