Cheap Metal-Catalyzed Directed Arylation Of Unactivated C-H Bonds

During the last several decades, transiton metal catalyzed unreactive C-H bond activation is of great research interest in organic chemistry. Compared with the use of noble second-or third-row transiton metals, the first-row transition metals would be more favorable and abundant, such as Mn, Fe, Co, Ni, Cu etc. On the other hand, the reactions based on the first-row transition metals catalyst usually displayed totally different or complementary catalytic reactivities. Because of this, the investigation of the first-row transition-metal catalytic system will enrich the diversity of the organic reactions.This dissertation is mainly focus on the studies of Cu, Ni catalzed C-H arylation, which include:1. Copper-/Silver-Mediated Direct Arylation of C(sp2)-H Bonds with 2-thiophenecarboxylic AcidsDecarboxylative arylation of unactivated (hetero)aryl C-H bonds mediated by a Cu/Ag bimetallic catalytic system has been achieved. The protocol features a broad substrate scope, high functional group tolerance, and good compatibility with heterocycle substrates providing a valuable synthetic access to biaryl carboxylic acids. Moreover, the versatility of this process is further demonstrated by a series of copper-catalyzed sequential C-H functionalization for synthesizing disubstituted benzoic acid derivatives. The mechanism study indicates a cascade protodecarboxylation/dehydrogenative cross-coupling process is plausibly involved in this reaction.2. Copper-catalyzed Oxidative C-H/C-H Cross-Coupling of Benzamides and ThiophenesGenerally, the copper catalyzed CDC reactions were limited to use stoichiometric copper catalyst and oxazole or thiazole as coupling parerners which contain acidic C-H bonds. Here, a copper-catalyzed oxidative C-H/C-H cross-coupling of nonacidic arenes (thiophenes) and (pyridin-2-yl)isopropyl amine (PIP-amine) as directing group has been developed, which exibits broad substrate scopes and excellent tolerance of functional groups. The directing group could be readily removed to afford 2-thienylbenzoic acids.3. Ni-catalyzed Ortho Arylation of Benzamides with ArylsilanesPreviously, the Ni catalzed arylation is based on Ni?/Ni? mechanism, the proposed mechanism including oxidative oxidation of iodobenzene or diaryliodonium Salts gives the high valent Ni(?) complex, after the subsequent reductive elimination and protonation to afford the desired product. Our work embarked on the development of Ni?/Ni? catalyzed arylation with arylsilanes reagent. This methodology proceed through single electron oxidant (Ag) to oxidize Ni(?) to Ni(?), after ligand exchange with organic silanes and reductive elimination to afford the corresponding product. Under optimal conditons, many functional groups are well tolerated and a variety of organic silanes with different groups could afford good to excellent yield.