Studies Of Palladium-Catalyzed C-H Bond Arylation Directed By The 2-Pyridylsulfinyl Group

Biaryls are important structural motifs frequently found in many pharmaceutically relevant and biologically active compounds. As a result, for over a century organic chemists have sought to develop new and more efficient aryl-aryl bond-forming methods. Among these researches, transition-metal-mediated reactions, such as Kumada coupling, Suzuki coupling, sonogashira coupling and so on. have become one of the powerful tools for the construction of aryl-aryl bonds. However, one main drawback of these methods is the requirement of the prefunctionalization of the substrates. Consequently, the development of transition-metal-catalyzed C-H activation transformations for the C-C bond construction has aroused great interest in recent years.This dissertation mainly focused on the studies of palladium-catalyzed C-H bond arylation directed by a removable group. Currently, auxiliary-assisted C-H bond activation has emerged as a powerful tool in organic synthesis. In the majority of arene C-H bond functionalization examples, a directing group has been used as a means of tuning the regioselectivity. Under this speculation, a 2-pyridyl unit, imines, oxymes, carboxylic acids, and N-acetyl or N-carbamoyl anilines have been successfully applied to achieve arene C-H bond functionalization. However, in some cases, the directing groups are not easily removed, hence compromising the practicality of the reaction. Therefore, the discovery of efficient removable directing groups is highly desirable. A palladium-catalyzed arylation of arene C-H bond assisted by a removable 2-pyridylsulfinyl group is described. The reaction employs aryltrifluoroborates as the arylation reagent, leading to the corresponding products in moderate to good yield with broad substrate scope. The directing group can be removed or converted to other useful functionalities, which showcases the potential synthetic application of the methodology.