Evelopment Of Coupling Reactions Based On Palladium-Catalyzed C-H Activations

Reactions forming a new C-C bond through the activation of inactive C-H bond is notonly a simple effective method building complex compounds from small molecules, but alsocan provide more economic, simple synthetic route. Among the reaction transaction metalsutilized as catalyst, Pd has shown to be exteremely effective catalyst,such transfer metlions.Through these development, C-C bond formation via Pd-catalyzed C-H activation hasevolved into a important tool in the modern organic synthesis. The article is divideed into fiveparts as follows:In chapter1, recent developments of C-H activation to form C-C bond using transitionmetal especially palladium as catalysts are summarized.In chapter2, Pd（TFA）₂catalyzed coupling reactions of acetanilide and ethyl glyoxylatewere discussed. Previous coupling reactions on benzaldehyde generate ketones as theproducts, Inthsi reaction, Anthranilic esters were obtained through a Pd-catalyzedehydrogenative decarbonylature coupling. After examining the reaction activity of catalysts,ligands, solvents and the ratio of acetanilide and ethyl glyoxylate, we found the optimizedreaction conditions for this transformation:1equiv of acetanilide was heated with2equiv ofethyl glyoxylate and4equiv of TBHP in the presence of5mol%of Pd（OAc）₂in benzene at120oC for12h, and another batch of Pd（TFA）₂（5mol%） was added. Using the optimizedreaction conditions several Anthranilic esters were prepared. In addition a possiblemechanism was proposed.In chapter3, PdCl2（PPh3）₂catalyzed coupling reactions of salicylaldehyde and1,2-dibromobenzene were discussed. After examining the activity of catalysts and solvents, theoptimized reaction conditions were found for this transformation:1equiv of salicylaldehydewas heated with2equiv of2-dibromobenzene and2equiv of potassium carbonate in thepresence of5mol%of PdCl2（PPh3）₂in benzene at120oC for12h. Using the optimizedreaction conditions, several xanthone were prepared. In addition a possible mechanism wasproposed.In chapter4, Pd-catalyzed coupling reactions of perfluoroarenes with aromaticheterocycles were discussed. Using the optimized reaction conditions, several heterocycliccompounds containing of polyfluoro benzene mooety were prepared. In addition a possiblemechanism was proposed. After examining various ratios of catalyst, base, oxidant,solution and reaction temperature, we explored the different reaction conditions for differentsubstrates. In chapter5, coupling reactions of benzyl alcohol and benzothiazole via potassiumperoxydisulfate oxidation were discussed. After examining the reaction coditions, we foundthe optimized reaction conditions for this transformation. Using the optimized reactionconditions, several2-phenyl-benzothiazole were prepared. In addition a possible mechanismwas proposed.