Iron-Catalyzed C(sp2)–H Bond Functionalization with Organoboron Compounds
摘要:
We report here that an iron-catalyzed directed CH functionalization reaction allows the coupling of a variety of aromatic, heteroaromatic, and olefinic substrates with alkenyl and aryl boron compounds under mild oxidative conditions. We rationalize these results by the involvement of an organoiron(III) reactive intermediate that is responsible for the CH bond-activation process. A zinc salt is crucial to promote the transfer of the organic group from the boron atom to the iron(III) atom.
Step economical synthesis of o-aryl benzamides via C–H activation relayed by the in situ installation of directing group: a multicomponent method
作者:Yunyun Liu、Yi Zhang、Meiying Huang、Jie-Ping Wan
DOI:10.1039/c5ra09078d
日期:——
Multicomponent reactions have been successfully applied as a platform for the step economical C–H activation based synthesis wherein the in situ installation of directing group and the subsequent C–H arylation have been achieved in one-step.
Versatile direct Hiyama‐type C−H arylations of benzamides were accomplished with organosiloxanes by chelation‐assisted cobaltcatalysis. The C−H arylation featured broad substrate scope, including challenging C(sp3)−H activation, the use of γ‐valerolactone as biomass‐derived solvent, and selectively provided the desired biaryls, even when being highly sterically hindered.
Intermediates and mechanism in iron-catalyzed C–H methylation with trimethylaluminum
作者:Shilpa Bhatia、Joshua C. DeMuth、Michael L. Neidig
DOI:10.1039/d1cc05607g
日期:——
A mechanistic study is performed on the reaction method for iron-catalyzed C–H methylation with AlMe3 reagent, previously proposed to involve cyclometalated iron(III) intermediates and an iron(III)/(I) reaction cycle. Detailed spectroscopic studies (57Fe Mössbauer, EPR) during catalysis and in stoichiometric reactions identify iron(II) complexes, including cyclometalated iron(II) intermediates, as
对铁催化 C-H 甲基化与 AlMe 3试剂的反应方法进行了机理研究,先前提出涉及环金属化铁(III)中间体和铁(III)/(I)反应循环。催化和化学计量反应过程中的详细光谱研究(57 Fe Mössbauer,EPR)确定铁 ( II ) 配合物,包括环金属化铁 ( II ) 中间体,作为在催化反应条件下原位形成的主要铁物质。反应研究确定了环金属化铁(II)-甲基物种作为关键中间体,在与氧化剂反应时导致 C-H 甲基化产物,这与先前提出的用于 C-H 芳基化的铁 ( II )/铁 ( III )/铁 ( I ) 反应歧管一致。
Nickel(II)-Catalyzed Direct Arylation of C–H Bonds in Aromatic Amides Containing an 8-Aminoquinoline Moiety as a Directing Group
作者:Ayana Yokota、Yoshinori Aihara、Naoto Chatani
DOI:10.1021/jo501697n
日期:2014.12.19
Arylation via the cleavage of the ortho CH bonds by a nickel-catalyzed reaction of aromatic amides containing an 8-aminoquinoline moiety with aryl iodides is reported. The reaction shows a high functional group compatibility. The reaction proceeds in a highly selective manner at the less hindered CH bonds in the reaction of meta-substituted aromatic amides, irrespective of the electronic nature of the substituents. Electron-withdrawing groups on the aromatic amides facilitate the reaction. Various mechanistic experiments, such as deuterium labeling experiments, Hammett studies, competition experiments, and radical trap experiments, have been made for better understanding the reaction mechanism. It is found that the cleavage of CH bonds is reversible on the basis of the deuterium labeling experiments. Both Ni(II) and Ni(0) show a high catalytic activity, but the results of mechanistic experiments suggest that a Ni(0)/Ni(II) catalytic cycle is not involved.