Oxygen-functionalizing Of Aromatic C-H Bond

The formation of carbon-carbon bonds is of great importance in organic chemistry, and transition metals play important roles in the formation of carbon-carbon bonds. For example, transition metals-catalyzed Heck reaction, Suzuki-Miyaura reaction, Stille reaction, and Sonogashira coupling reaction are versatile tools for formation of carbon-carbon bonds. However, one main drawback of those methods is the requirement of the prefunctionalization of the substrates. Consequently, the development of transition metals-catalyzed C-H bond activation transformations provides the more efficient ways for the C-C bond construction, and the related research has aroused great interest. The reactivity and selectivity are the great challenges in C-H activation.Diaryliodonium salts, act as arenirm ion transfer reagents in organic synthesis, which is able to react with various nucleophilic substrate to realize the substrate arylation. Using this special property, the dissertation mainly focused on the studies of oxygen-functionalizing of aromatic C-H bond and palladium-catalyzed cross-coupling reactions.This dissertation describe from the following aspects:Partâ… : study on synthesis and properties of diaryliodonium saltsBased on a large amount of literature, a variety of ten diaryliodonium salts were successfully synthesized under the mild conditions via five simple methods, and with an excellent yield and purity of the products. In this process, we also prepared multiple practical organic high iodine compounds, such as iodobenzene diacetate, Koser's reagent, etc.Partâ…¡: oxygen-functionalizing of aromatic C-H bondThe diaryliodonium salts we had prepared were applied in oxygen-functionalizing of aromatic C-H bond and the reaction conditions were optimized, we also explored functionalizing of aromatic C-H bond in the reductive elimination reaction on different anions and diaryliodonium salts with various substitution. This method splendidly realized aromatic ring oxidation with the mild reaction condition, simple operation. Most importantly of all, it was differ from conventional methods of aromatic C-H bond activation (transition metal catalyzed, the positioning group, etc.), without transition metal participation and positioning group, environmental friendly and almost quantitative yields.Partâ…¢: palladium-catalyzed cross-coupling reactionsThe diaryliodonium salts we had prepared were applied in palladium-catalyzed C-C bond cross-coupling reactions. The optimized reaction conditions and the general of substrates had been studied. In addition, we also explored cross-coupling reactions of different anionic diaryliodonium salts and diverse substituent aromatic compounds, the cross-coupling products, reaction time and yields were investigated. The results reveal that diaryliodonium salts splendidly realized arylation of aromatic compounds with the mild reaction condition and simple operation. In transition metal catalyzed cross-coupling reactions, the substrate almost contains positioning groups which could promote the reaction, and the reaction time is generally longer, all kinds of complicated ligand were needed. The advantage of cross-coupling method we had selected is without positioning groups, and unnecessary to add ligands for promoting reaction, with shorted reaction time and considerable yields.