| The thesis is divided into two parts::The first part is concering about the synthesis of pincer complexes and their application. Since reported by Shaw and van Koten in the1970s, due to their high stability, activity and adjustability, pincer complexes have been well developed, and been widely used in organic synthesis, catalysis, sensors, and supramolecular chemistry fields. Pincer ligand may be abbreviated as [EYE], wherein Y represents a donor center (Y=C, N, etc.), E represents the image amine (-NR2), phosphine (-PR2), phosphorous acid (-P(OR)2), ether (-OR), thioether (-SR), selenides (-SeR), N-heterocyclic arbine (the NHCs)) and so on.According to the kinds of arm donor atoms, pincer complexes can be divided into two types, symmetric pincer complexes have two identical donor atoms abbreviated as [EYE] and unsymmetric pincer complexes have two different donor atoms abbreviated as [EYE’]. For symmetric pincer [EYE] complexes, their biggest advantage was their very simple synthesis and easy modification to the structure, so they have been very extensively studied. In contrast, the study found that for the unsymmetric pincer [EYE’] complexes, the cooperation effect of two different donor atoms may have very unique characteristics and therefore has higher activity, and therefore [EYE’] unsymmetric type of pincer complexes have attracted the interest of more and more researchers. However, due to the relatively complex synthesis, reports of [EYE’] unsymmetric type of pincer complexes were far less than [EYE] symmetrical type of pincer complexes.In the study of the pincer complexes, palladium, ruthenium, rhodium, ruthenium and other noble metal catalyst were most studied, but their shortcomings are obvious because of expensive and serious environmental pollution. Compared to them, nickel is cheaper, less toxic and more environmentally friendly.In this paper, we synthesized the [PCP] symmetric pincer nickel complexes based on known methods in the literature and another new [CNN] unsymmetric type pincer nickel complexes. Kumada coupling of chlorinated aromatics with Grignard reagents was chosen to investigated their activities, it was found that under mild reaction conditions the two types of complexes both showed good reactivity, and the universality of the substrate is also very good. It is worth mentioning that for the double couplings of aryl dichlorides, pincer nickel complexes also showed excellent catalytic activities.The second part was about transition-metal-free synthesis of Fluorinated Arenes from perfluorinated arenes coupled with Grignard Reagents. Fluorinated compounds have great application in pesticide intermediates, medicine and other physiologically active compounds, however, fluorinated organic compounds in nature are very rare, so far only dozens of compounds found in natural contain C-F bond. Therefore, selectively introducing fluorine atom or fluorine-containing group into the organic molecules has attracted many organic chemist’s interest.In this part of the work we have found a simple way to get fluoride aromatic compounds, without the presence of transition metal catalyst, Synthesis of Fluorinated arenes from perfluorinated arenes coupled with Grignard Reagents. Though in the1950s and1960s there was once reported the similar reactions, but because low yields and low selectivity, few attention has concering about this discovery. In this article, we found that perfluorinated aromatic compounds react with Grignard reagents under relatively mild conditions, and higher yields can be obtained for polyfluorinated aromatic compounds.We studied the mechanism of this reaction and proposed a four-membered ring transition state, and supported by theoretical calculations. Special noted that perfluorinated aromatic compounds not only react with aryl Grignard reagent, but also the reaction with alkyl Grignard reagent give moderate to good yields. |
PDF Full Text Request