Study On Thioetherification And Phosphorylation Based On Cross-dehydrogenation Coupling

With the development of modern chemistry,chemical reactions are required to be more efficient,reaction conditions are milder,reaction results are more environmentally friendly,atomic utilization is higher,and by-products are less.Therefore,the cross-dehydrogenation coupling reaction（CDC reaction）has attracted the interest of researchers.Based on the cross-dehydrogenation coupling reaction,the carbon-sulfur bond,carbon-phosphine bond and nitrogen-phosphine bond were constructed under mild conditions.The research content is divided into the following three parts:（1）In the second chapter of this thesis,the carbon-sulfur bond formation reaction ofβ-dicarbonyl compound and thiophenol is studied.A series ofβ-carbonyl thioethers can be efficiently synthesized at room temperature in the presence of air and Cs₂CO₃.Thiyl radical is generated from the autoxidation of thiol in the presence of Cs₂CO₃ and dioxygen,and thiyl radical undergoes homocoupling to produce disulfide.The active methylene compound reacts with Cs₂CO₃ to form an enol intermediate.The nucleophilic attack of the in situ-generated enolate on disulfide affordsβ-carbonyl thioethers.The method is based on the CDC reaction of thiophenol withβ-dicarbonyl compound,and realizes an efficient and practical method for synthesizingβ-carbonyl sulfide compound without halogen and precious metal.（2）The third chapter of this thesis mainly studies the phosphonylation reaction of xanthene and diarylphosphine oxide by using 2,3-dichloro-5,6-dicyanobenzoquinone（DDQ）as oxidant.Initially,a single-electron transfer process between xanthene derivatives and DDQ generates the radical ion pair.Afterwards,the benzylic radical is formed via a proton abstraction by the DDQ radical anion.The second single-electron transfer process generates the benzylic cation and the DDQH anion.The diarylphosphine oxide acts as a nucleophile and the P（III）form via the tautomerization,attacks the benzylic cation to produce the unstable phosphonium cation.The subsequent deprotonation produces the phosphonylated product of xanthene.（3）The fourth chapter of this thesis mainly studies the phosphonylation reaction of imine and diarylphosphine oxide.By using t-butyl hydroperoxide（TBHP）as oxidant and under the catalysis of iodide,this method can synthesize a phosphoimide compound in one step.