New Catalysts And Ligands For Synthesis Of Vinyl Biphenyl Compounds

Palladium-catalyzed Suzuki-Miyaura coupling reaction has become one of the most widely useful tools for the synthesis of biaryls in organic chemistry. Generally, phosphine ligands are required to stabilize the active palladium species in the palladium-catalyzed Suzuki-Miyaura coupling reactions. However, many of the tert-phosphine ligands are sensitive to air, and they are also expensive, toxic, and unrecoverable, which result in significant limitations on their synthetic applications. Therefore, most of N-ligands which are inexpensive, easy to access and stable in the air and water have gained major attention. In addition, because of their low cost, low toxicity and high chemical stability, other inorganic complexes, for example manganese salts, cobalt salts, iron salts, have recently been actively investigated in Suzuki-Miyaura coupling reaction. But few manganese, cobalt, and iron salts have been used successfully in Suzuki-Miyaura coupling reaction.In this dissertation, the Suzuki-Miyaura coupling reaction was studied mainly from two aspects:Synthesis of 4-substituted styrene compounds (including vinyl group substituted liquid crystal compounds) by palladium catalyzed Suzuki-Miyaura coupling reaction using dinitrogen ligands. The Suzuki-Miyaura coupling reaction catalyzed by manganese, cobalt, and iron salts hve been investigated in detail, as follows:1. Pd(Ⅱ)/Schiff-base L1-L7 catalyzed Suzuki-Miyaura coupling reactions of aryl bromides were investigated. The results showed that the palladium catalyzed Suzuki-Miyaura coupling reactions can be effectively promoted by big bulk and strong rigidity L7 for the synthesis of 4-vinyl biphenyl compounds, and the highest yield could be up to 92%. The catalytic system has excellent functional group tolerance. And the catalyst system was also suit for synthesis of liquid crystals compounds and obtained 88%-92% good yields at the optimized reaction conditions.2. Pd(Ⅱ)/L8-L10 catalyzed Suzuki-Miyaura coupling reactions of aryl bromides were investigated. The results showed that the palladium catalyzed Suzuki-Miyaura coupling reactions can be effectively promoted by the L10 with strong electron donor effect and large steric hindrance effectively for the synthesis of 4-vinyl biphenyl compounds, and the highest yield could be up to 91%. And the catalyst system was also suit for synthesis of liquid crystals compounds and obtained 60%-75% satisfying yields at the optimized reaction conditions. 3. Pd(Ⅱ)/1,2-diamines catalyzed Suzuki-Miyaura coupling reactions of aryl bromides were investigated. Although 1,2-diaminocyclohexane/PdCl2(CH3CN)2 and 2,3-butanediamine/PdCl2(CH3CN)2 can catalyze Suzuki-Miyaura coupling reactions, but the results are average. However, the catalyst system of 1,2-diaminocyclohexane/ PdCl2(CH3CN)2 is obviously better than its of 2,3-butanediamine/PdCl2(CH3CN)2 for the synthesis of 4-vinyl biphenyl liquid crystal compounds, and the yields are in 84%-89%.4. Palladium porphyrins complexes 15-18 have been synthesized. The complex 17 was an efficient catalyst for Suzuki-Miyaura coupling reactions between aryl bromides and arylboronic acids in toluene with 0.1% loading, TON is up to 6×104. The electronic effect of ligands on palladium porphyrins complexes catalyzed the Suzuki-Miyaura coupling reaction has a significant influence, the ligand with the electron-donating groups (-OMe,17), its palladium complex catalytic activity was significantly higher than the ligands with an electron-withdrawing groups (-C1,16; 5F,18).5. The catalytic activity of various manganese salts, iron salts, and cobalt salts was investigated in the Suzuki-Miyaura coupling reaction. The inorganic complexes Mn(OAc)2·4H2O, FeCl2·4H2O and CoCl2·6H2O could catalyze Suzuki-Miyaura coupling reactions of aryl bromides or iodides with arylboronic acids. The optimized reaction conditions are aryl bromides or iodides (0.5 mmol), arylboronic acids (0.75 mmol), inorganic complexes (5.0 mol%, relative to aryl bromide), ethanol as solvent,75℃in the presence of K2CO3 as the base. Although the catalytic system has poor functional group tolerance for the reaction substrates, some result was satisfactory, and the best yield can be up to 99%.