Fluorinated biphenyls from aromatic arylations with pentafluorobenzenediazonium and related cations. Competition between arylation and azo coupling
作者:Dmitry Kosynkin、T. Michael Bockman、Jay K. Kochi
DOI:10.1039/a701745f
日期:——
High yields of the mixed perfluorinated biaryls (C6F5–Ar) are obtained by the catalytic dediazoniation of the pentafluorobenzenediazonium salt (C6F5N2+BF4–) in acetonitrile solutions containing various aromatic substrates (ArH) together with small amounts of iodide salts. Activated (electron-rich) as well as deactivated (electron-poor) arenes are successfully pentafluorophenylated by this method. The arylation is distinct from the azo coupling of the same substrates, which takes place in the absence of the iodide catalyst and yields the corresponding diazene (C6F5NN–Ar) as product. The catalytic role of iodide, and the isomeric product distributions obtained with this procedure indicate that the arylation proceeds via the pentafluorophenyl radical in a efficient homolytic chain process. Since azo coupling involves electrophilic aromatic substitution of electron-rich ArH by C6F5N2+, the two competing pathways are distinct and do not have reactive intermediates in common.
An Efficient Method for Sterically Demanding Suzuki-Miyaura Coupling Reactions
作者:Qing Zhao、Chengxi Li、Chris H. Senanayake、Wenjun Tang
DOI:10.1002/chem.201203898
日期:2013.2.11
An efficientmethod for sterically demanding Suzuki–Miyauracoupling reactions has been developed with two catalysts, Pd/BI‐DIME (see scheme) and Pd/phenanthrene‐based ligand. The Pd/BI‐DIME catalyst facilitates the syntheses of extremely hindered biaryls bearing ortho‐isopropyl substituents. The other catalyst is efficient for the synthesis of functionalized tetra‐ortho‐substituted biaryls at low
[Pd(μ-Cl)Cl(IPr*)]<sub>2</sub>: a highly hindered pre-catalyst for the synthesis of tetra-ortho-substituted biaryls via Grignard reagent cross-coupling
作者:Mathieu Lesieur、Alexandra M. Z. Slawin、Catherine S. J. Cazin
DOI:10.1039/c4ob01269k
日期:——
The new well-defined catalyst [Pd(μ-Cl)Cl(IPr*)]2 enables the efficient Grignard reagent cross-coupling for the synthesis of tetra-ortho-substituted biaryls.
The present invention is a one-step method for efficiently converting carbon-hydrogen bonds into carbon-carbon bonds using a combination of aryl halides, a substrate, and a copper salt as catalyst. This method allows faster introduction of complex molecular entities, a process that would otherwise require many more steps. This invention is particularly relevant for the organic synthesis of complex molecules such as, but not limited to, pharmacophores and explosives.
Palladium‐Catalysed C−H Bond Zincation of Arenes: Scope, Mechanism, and the Role of Heterometallic Intermediates
作者:Martí Garçon、Nicolette Wee Mun、Andrew J. P. White、Mark R. Crimmin
DOI:10.1002/anie.202014960
日期:2021.3.8
of paramount importance in synthesis. A particular focus has been the generation of organoboranes, organosilanes and organostannanes from simple hydrocarbons (X=B, Si, Sn). Despite the importance of organozinc compounds (X=Zn), their synthesis by the catalytic functionalisation of C−H bonds remains unknown. Herein, we show that a palladium catalyst and zinc hydride reagent can be used to transform C−H