Palladium-catalyzed Arylation Of Sp~3C-H Bond Assisted By An N,O-bidentate Directing Group

In this thesis, we have developed a method for auxiliary-directed, palladium-catalyzed β-arylation of sp3C-H bonds in carboxylic acid derivatives. The method employs2-propionamidopyridine1-oxide as N,O-bidentate directing group, aryl iodide coupling partner, palladium acetate catalyst. Preliminary mechanistic studies have been performed. A CNO-palladacycle intermediate has been isolated, characterized by X-ray crystallography. The main results are as follows:1. Synthesis and characterization of2-propionamidopyridine1-oxide2-propionamidopyridine1-oxide complexes1were synthesized (Scheme1,2) using propionic acid derivative and2-aminopyridine1-oxide according to the literature in two different ways. The new complexes were characterized by1H NMR,13C NMR,19F NMR and HRMS.2. Palladium-catalyzed β-arylation of sp3C-H bonds2-propionamidopyridine1-oxide1a and iodobenzene were choosen as the model substrates to optimize suitable conditions. Based on the results, we employ palladium acetate as catalyst, dipotassium hydrogen phosphate trihydrate as base, dimethyl sulfoxide as solvent at120oC, affording the β-arylation of sp3C-H bonds (Scheme3). The new complexes were characterized by1H NMR,13C NMR,19F NMR and HRMS. 3. The remove of N,O-bidentate directing groupThe N,O-bidentate directing group can be removed under base hydrolysis affording a3-Phenylpropionic acid derivative (Scheme4).