A C–H Borylation Approach to Suzuki–Miyaura Coupling of Typically Unstable 2–Heteroaryl and Polyfluorophenyl Boronates
摘要:
A method for the synthesis of biaryls and heterobiaryls from arenes and haloarenes without the intermediacy of unstable boronic acids is described. Pinacol boronate esters that are analogous to unstable boronic acids are formed in high yield by iridium-catalyzed C-H borylation of heteroarenes and fluoroarenes. These boronates are stable in the solid state or in solution and can be generated and used in situ. They couple with aryl halides in the presence of simple palladium catalysts, providing a convenient route to biaryl and heteroaryl products that have been challenging to prepare via boronic acids.
An efficient phosphine-free direct C–Harylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1–0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or
Palladium Nanoparticles in Suzuki Cross-Couplings: Tapping into the Potential of Tris-Imidazolium Salts for Nanoparticle Stabilization
作者:Marc Planellas、Roser Pleixats、Alexandr Shafir
DOI:10.1002/adsc.201100574
日期:2012.3
magnetic resonance, transmission electron microscopy, electron diffraction and dynamic light scattering. The new materials proved effective in Suzuki cross‐coupling at a loading of 0.2% palladium. Thus, using a tris‐imidazolium iodide‐palladium material, a series of biaryl products has been prepared starting from aryl bromides and some activated chlorides. The possibility that this catalytic activity might
受各种钯源在咪唑基离子液体中形成纳米颗粒的倾向性的启发,我们现在报道带有十六烷基链和桥连间苯三甲部分的三咪唑盐是有效的钯纳米颗粒稳定剂,是通过钯的Chaudret型氢化有效制备的。双(二亚苄基丙酮)钯(0)。钯纳米粒子已经以纯净形式分离出来,其特征为1H核磁共振,透射电子显微镜,电子衍射和动态光散射。在钯含量为0.2%的情况下,新材料在铃木交叉偶联中被证明是有效的。因此,使用碘化三咪唑鎓钯材料,已从芳基溴化物和一些活化的氯化物开始制备了一系列联芳基产品。这种可能性,这催化活性可能是由于钯n中形成-杂环卡宾已通过固态寻址13 C NMR,并且其中所述酸性2-H用甲基取代的咪唑鎓类似物的合成。
Solvent-Free Palladium-Catalyzed Direct Arylation of Heteroaromatics with Aryl Bromides
作者:Souhila Bensaid、Henri Doucet
DOI:10.1002/cssc.201100771
日期:2012.8
course of catalyzed directarylations. Some palladium‐catalyzed directarylations of heteroaromatics can be advantageously performed without any solvent. In the presence of palladiumcatalysts (1 mol %) and potassium acetate as the base, the direct 5‐arylation of some thiazoles, thiophenes, furans, or pyrroles with arylbromides as coupling partners proceeds highly regioselectively and in moderate to
Microwave-assisted, ligand-free, direct C–H arylation of thiophenes in biomass-derived γ-valerolactone
作者:Silvia Tabasso、Emanuela Calcio Gaudino、Laura Rinaldi、Audrey Ledoux、Paolo Larini、Giancarlo Cravotto
DOI:10.1039/c7nj01540b
日期:——
Pd-catalyzed C–H arylation of heterocycles with aryl halides is a straightforward and more environmentally-friendly route to the synthesis of well-defined, pi-conjugated polymers for challenging applications in electronic devices. Although this type of transformation is more atom efficient than cross-couplings, it still poses environmental issues in the form of reaction media and the use of phosphine ligands
Iridium Catalysis for CH Bond Arylation of Heteroarenes with Iodoarenes
作者:Benoît Join、Takuya Yamamoto、Kenichiro Itami
DOI:10.1002/anie.200806358
日期:2009.5.4
Efficient couplings using equimolar quantities of each coupling partner and multiple CHbondarylation reactions are achieved with an Ir‐based catalytic system for the CHbondarylation of electron‐rich heteroarenes with iodoarenes to construct extended π‐systems. The dramatic ligand effect on reaction efficiency leads to the discovery that Crabtree's catalyst (see scheme) is the optimal catalyst