Palladium-Catalyzed Desulfitative Cross-Coupling Of ?-oxo Ketene Dithioacetals With Aryl Iodides

In recent years,transition metal-catalyzed desulfurization cross-coupling reactions of organic sulfides have been paid more and more attention in the field of carbon-carbon bond synthesis methodology.Compared with the organo-halide reagents in traditional cross-coupling reactions,the organic sulfide has the characteristics of diverse structure,low cost and easy availability,and stable properties.The study of cross-coupling reactions based on organic sulfides is of great guiding significance for the establishment of new carbon-carbon bond construction methods and for the expansion of cross-coupling reactions.?-oxo ketene-(S,S)acetals is a type of?,?-unsaturated carbonyl compound,which has the structural characteristics of intercalated thioesters.Because of?-oxo ketene-(S,S)acetals has multiple reaction sites and variable functional groups,it is widely used in synthesis.Our research group has been engaged in the research of ketene dithioacetals chemistry for a long time,and has successfully developed it into a functionalized organic conjugate,and has established a series of new ways of carbon-carbon bond formation.Sulfur has a strong poisoning effect on transition metals and is not conducive to the circulation of catalysts,so there are few reports on cross-coupling reactions for desulfurization catalyzed by transition metals.This thesis explored the cross-coupling reaction between the electrophilic reaction site(?-position)of?-oxo ketene-(S,S)acetals and the desulfurization coupling reaction of aryl iodine electrophiles under the catalysis of transition metal palladium.Meanwhile,a new method of reductive cross-coupling has been developed to provide new content for the activation and transformation of carbon-sulfur bonds.This thesis mainly includes the following content:1.This thesis briefly describes the reaction characteristics and application of?-oxo ketene-(S,S)acetals as an intermediate in organic synthesis,and summarizes the reaction types of C(sp~2)-S bond activation and new C-C bond construction.Combined with previous work,using?-oxo ketene-(S,S)acetals as an organic coupling body,we developed a new method for desulfurization cross-coupling reaction and carbon-carbon bond construction.2.We developed the reduction cross-coupling reaction of two types of electrophiles,?-carbonyl dithioketal and aromatic iodide.Using the easily available?-carbonyl dithioketal as an organic sulfur conjugate,under the catalysis of bis(triphenylphosphine)palladium dichloride,we achieved cross-coupling of?-carbonyl dithioketal and aromatic iodine through the C(sp~2)-S bond activation of?-carbonyl dithioketal and in-situ formation of aryl zinc halide.This is the first coupling at the?-position of the electrophilic reaction site of?-oxo ketene-(S,S)acetals with an aromatic iodide electrophile,which provides new content for the study of reductive cross-coupling methodology.In addition,the structures of?-carbonyl dithioketal and aromatic iodine are diverse.The new reaction developed in this thesis expands the new synthetic pathways of tri-and tetra-substituted alkenes.