Ruthenium-Catalyzed C-H Bond Activations And Palladium- And Nickel-Catalyzed C-C Coupling Reactions In PEG-400

With the rapid development of social economy, chemistry is changing. Whether from the perspective of the kinds of synthesized compounds or from the perspective of the research methods of chemistry, chemistry now is different from early years. However, in the development of chemistry at the same time, the pollution to the environment is becoming more and more serious, the development of green chemistry has attracted much attention.Polyethylene glycols（PEGs） have a lot of advantages such as low toxicity, nonpollution, non-volatile, cheap and easy to get. It can dissolve the most of organic and inorganic compounds and can be recycled. PEGs have turned out to be a great green solvent and been widely used in organic synthesis in recent years. What this thesis mainly studied is the C–C bond formations reactions catalyzed by ruthenium, palladium and nickel in PEGs and the recycling of the catalysts in PEGs. The whole work is divided into four parts:The first part: we investigated ruthenium（Ⅱ）-catalyzed C-H bond functionalization/ C–C coupling reaction of functional arenes in PEG-400. Firstly, we performed the direct ortho arylation of functional arenes with aryl chlorides at 100 oC in PEG-400 using [RuCl₂（p-cymene）]₂ as catalyst with K₂CO₃ as base and KOPiv as additive, furnishing the target biarylated products in high yields. Then, we investigated the selective monoarylation of 2-phenylpyridine with aryl chlorides in PEG-400 with RuCl₂（PPh₃）（p-cymene） as a catalyst leading to the monoarylated products in good yields. In addition, we found that both the [RuCl₂（p-cymene）]₂/PEG-400 and the RuCl₂（PPh₃）（p-cymene）/PEG-400 systems can be recycled for several times.The second part: we investigated the [Ru₂Cl₃（p-cymene）2][PF₆]-catalyzed oxidative annulation of alkynes by N-2-pyrimidyl-substituted anilines using Cu（OAc）₂·H₂O as oxidant in a mixture of PEG-400 and H₂O. The experimental results showed that the catalytic system had broad scope of substrates and the reactions generated a variety of indole derivatives in good to excellent yields. More importantly, the catalytic system can be reused for four times without any decrease in catalytic activity. The third part: we investigated palladium-catalyzed Stille cross-coupling reaction performed in PEG-400 to prepare biaryl compounds. We used sodium acetate as base and Pd（PPh₃）₄ as catalyst to perform the cross-coupling reaction of aryl halides with organotin reagents at 80 oC in PEG-400. It was found that the reaction of aryl halides with organotin reagents proceeded smoothly to afford the corresponding coupled products in high yield. The reaction has the advantages of short reaction time, mild reaction conditions, and recycle of the catalytic system.The fourth part: in this part, we investigated the Suzuki coupling reaction catalyzed by NiCl₂（dppp） in PEG-400 to prepare biaryls. The results showed that the catalytic system had broad scope of substrates and the reactions of both aryl bromides and aryl chlorides with arylboronic acids proceeded smoothly, affording a variety of biaryls in good to excellent yields. More importantly, the NiCl₂（dppp）/PEG-400 system can be recycled five times without significant loss of catalytic efficiency, which provides a new and green way to synthesize biaryl compounds.