scholarly journals Mechanochemistry allows carrying out sensitive organometallic reactions in air: glove-box-and-Schlenk-line-free synthesis of oxidative addition complexes from aryl halides and palladium(0)

2019 ◽  
Vol 10 (22) ◽  
pp. 5837-5842 ◽  
Author(s):  
Koji Kubota ◽  
Rina Takahashi ◽  
Hajime Ito
Keyword(s):  
Oxidative Addition ◽  
Aryl Halides ◽  
Organometallic Reactions ◽  
Wide Range

We have demonstrated that mechanochemistry allows synthesizing a wide range of palladium oxidative addition complexes in air.

scholarly journals Controlling Non-Native B12 Reactivity and Catalysis in the Transcription Factor CarH

2021 ◽  
Author(s):  
Xinhang Yang ◽  
Benjamin H. R. Gerroll ◽  
Yuhua Jiang ◽  
Amardeep Kumar ◽  
Yasmine S. Zubi ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Vitamin B12 ◽  
Transcription Regulation ◽  
Bond Cleavage ◽  
Oxidative Addition ◽  
Mechanistic Studies ◽  
Organic Transformations ◽  
Carbon Bond ◽  
Wide Range ◽  
Hydride Elimination

Vitamin B12 derivatives catalyze a wide range of organic transformations, but B12-dependent enzymes are underutilized in biocatalysis relative to other metalloenzymes. In this study, we engineered a variant of the transcription factor CarH, called CarH*, that catalyzes styrene C-H alkylation with improved yield and selectivity relative to B12 itself. While the native function of CarH involves transcription regulation via AdoCbl Co(III)-carbon bond cleavage and β-hydride elimination to generate 4’,5’-didehydroadenosine, CarH*-catalyzed styrene alkylation proceeds via non-native oxidative addition and olefin addition coupled with a native-like β-hydride elimination. Mechanistic studies on this reaction echo findings from earlier studies on AdoCbl homolysis under strong cage conditions to suggest that CarH* can enable non-native radical chemistry with improved selectivity relative to B12 itself. These findings lay the groundwork for the development of B12-dependent enzymes as catalysts for a wide range of non-native transformations.

scholarly journals Direct Base-Assisted C‒H Cyclonickelation of 6-Phenyl-2,2′-bipyridine

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 997
Author(s):  
Nicolas Vogt ◽  
Vasily Sivchik ◽  
Aaron Sandleben ◽  
Gerald Hörner ◽  
Axel Klein
Keyword(s):  
Elevated Temperature ◽  
Title Compound ◽  
Noble Metals ◽  
Oxidative Addition ◽  
Base Metals ◽  
Base Pairs ◽  
Reaction Conditions ◽  
Wide Range ◽  
The World ◽  
First Time

The organonickel complexes [Ni(Phbpy)X] (X = Br, OAc, CN) were obtained for the first time in a direct base-assisted arene C(sp2)–H cyclometalation reaction from the rather unreactive precursor materials NiX2 and HPhbpy (6-phenyl-2,2′-bipyridine) or from the versatile precursor [Ni(HPhbpy)Br2]2. Different from previously necessary C‒Br oxidative addition at Ni(0), an extended scan of reaction conditions allowed quantitative access to the title compound from Ni(II) on synthetically useful timescales through base-assisted C‒H activation in nonpolar media at elevated temperature. Optimisation of the reaction conditions (various bases, solvents, methods) identified 1:2 mixtures of acetate and carbonate as unrivalled synergetic base pairs in the optimum protocol that holds promise as a readily usable and easily tuneable access to a wide range of direct nickelation products. While for the base-assisted C‒H metalation of the noble metals Ru, Ir, Rh, or Pd, this acetate/carbonate method has been established for a few years, our study represents the leap into the world of the base metals of the 3d series.

Stereoselectivity in Organometallic Reactions:  Oxidative Addition of Alkyl Halides to Platinum(II)

1998 ◽  
Vol 17 (13) ◽  
pp. 2805-2818 ◽  
Author(s):  
Cliff R. Baar ◽  
Hilary A. Jenkins ◽  
Jagadese J. Vittal ◽  
Glenn P. A. Yap ◽  
Richard J. Puddephatt
Keyword(s):  
Oxidative Addition ◽  
Alkyl Halides ◽  
Organometallic Reactions

Oxidative Addition of Aryl Halides to Transient Anionic à-Aryl–Palladium(0) Intermediates—Application to Palladium-Catalyzed Reductive Coupling of Aryl Halides

1996 ◽  
Vol 2 (8) ◽  
pp. 957-966 ◽  
Author(s):  
Christian Amatore ◽  
Emmanuelle Carré ◽  
Anny Jutand ◽  
Hideo Tanaka ◽  
Qinghua Ren ◽  
...  
Keyword(s):  
Oxidative Addition ◽  
Aryl Halides ◽  
Reductive Coupling ◽  
Palladium Catalyzed

scholarly journals Oxidative Addition of Aryl Halides to a Ni(I)-Bipyridine Complex

2022 ◽  
Author(s):  
Stephen Ting ◽  
Wendy Williams ◽  
Abigail Doyle
Keyword(s):  
Oxidative Addition ◽  
Aryl Halides ◽  
Solution Phase ◽  
Nickel Catalysis ◽  
Mechanistic Studies ◽  
Redox Equilibrium ◽  
Aryl Bromides ◽  
First Time

The oxidative addition of aryl halides to bipyridine- or phenanthroline-ligated nickel(I) is a commonly proposed step in nickel catalysis. However, there is a scarcity of complexes of this type that both are well-defined and undergo oxidative addition with aryl halides, hampering organometallic studies of this process. We report the synthesis of a well-defined Ni(I) complex, [(CO2Etbpy)NiCl]4 (1). Its solution-phase speciation is characterized by a significant population of monomer and a redox equilibrium that can be perturbed by π-acceptors and σ-donors. 1 reacts readily with aryl bromides, and mechanistic studies are consistent with a mechanism proceeding through an initial Ni(I) → Ni(III) oxidative addition. Such a process was demonstrated stoichiometrically for the first time, affording a structurally characterized Ni(III) aryl complex.

scholarly journals Aminoalkyl radicals as halogen-atom transfer agents for activation of alkyl and aryl halides

Science ◽  
2020 ◽  
Vol 367 (6481) ◽  
pp. 1021-1026 ◽  
Author(s):  
Timothée Constantin ◽  
Margherita Zanini ◽  
Alessio Regni ◽  
Nadeem S. Sheikh ◽  
Fabio Juliá ◽  
...  
Keyword(s):  
Halogen Atom ◽  
Building Blocks ◽  
Aryl Halides ◽  
Atom Transfer ◽  
Reduction Potentials ◽  
Tributyltin Hydride ◽  
Organic Halides ◽  
Wide Range ◽  
Carbon Carbon Bonds ◽  
Radical Processes

Organic halides are important building blocks in synthesis, but their use in (photo)redox chemistry is limited by their low reduction potentials. Halogen-atom transfer remains the most reliable approach to exploit these substrates in radical processes despite its requirement for hazardous reagents and initiators such as tributyltin hydride. In this study, we demonstrate that α-aminoalkyl radicals, easily accessible from simple amines, promote the homolytic activation of carbon-halogen bonds with a reactivity profile mirroring that of classical tin radicals. This strategy conveniently engages alkyl and aryl halides in a wide range of redox transformations to construct sp3-sp3, sp3-sp2, and sp2-sp2 carbon-carbon bonds under mild conditions with high chemoselectivity.

Aldehydes and Ketones Influence Reactivity and Selectivity in Nickel-Catalyzed Suzuki-Miyaura Reactions

2019 ◽  
Author(s):  
Alasdair Cooper ◽  
David Leonard ◽  
Sonia Bajo ◽  
Paul Burton ◽  
David Nelson
Keyword(s):  
Carbonyl Group ◽  
Functional Groups ◽  
Oxidative Addition ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Aryl Halides ◽  
Cross Coupling Reaction ◽  
Site Selectivity ◽  
Aldehydes And Ketones ◽  
The Cross

We show that the energetically-favorable coordination of aldehydes and ketones – but not esters – to nickel(0) during Suzuki-Miyaura reactions can lead either to exquisite selectivity and enhanced reactivity, or to the inhibition<br>of the reaction. Aryl halides where the C-X bond is connected to the same π-system as an aldehyde or ketone functional<br>group undergo unexpectedly rapid oxidative addition, and are selectively cross-coupled during inter- and intramolecular<br>competition reactions. When aldehydes and ketones are present elsewhere, such as in the form of exogenous additives,<br>the cross-coupling reaction is inhibited depending on how strongly the pendant carbonyl group can coordinate to nickel(0). This work advances our understanding of how common functional groups interact with nickel(0) catalysts, and presents synthetic chemists with a tool that can be used to achieve site-selectivity in functionalized molecules. <br>

Intermolecular Oxidative Addition of Aryl Halides to Platinum(II) Alkyl Complexes

2018 ◽  
Author(s):  
Kristof Altus ◽  
Eric Bowes ◽  
D. Dawson Beattie ◽  
Jennifer Love
Keyword(s):  
Aryl Halide ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Aryl Halides ◽  
Alkyl Complexes ◽  
Species Isolation

We report the first well-defined example of intermolecular aryl halide oxidative addition (OA) to Pt(II). Complexes of the type (IMes)PtMe<sub>2</sub>(L) and (IMes’)PtMe(L) (L = SMe<sub>2</sub>, pyridine; IMes = <i>N,N</i>-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; IMes’ = cyclometalated IMes) undergo intermolecular OA of phenyl iodide (PhI) at 60 °C, producing toluene <i>via</i> reductive elimination from a proposed Pt(IV)-phenyl species. Isolation of a model Pt(IV) OA product provides evidence for a Pt(II)/(IV) pathway. The OA of PhI is not limited to Pt(II)-IMes complexes;analogous reactions also proceed with phosphine-ligated Pt(II) dialkyl complexes, demonstrating that this reaction is feasible for a variety of electron-rich Pt(II) complexes bearing labile ligands.

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