Synthetic, Structural, and Mechanistic Studies on the Oxidative Addition of Aromatic Chlorides to a Palladium (N-Heterocyclic Carbene) Complex:  Relevance to Catalytic Amination

2003 ◽  
Vol 125 (33) ◽  
pp. 10066-10073 ◽  
Author(s):  
Alexandra K. de K. Lewis ◽  
Stephen Caddick ◽  
F. Geoffrey N. Cloke ◽  
Norman C. Billingham ◽  
Peter B. Hitchcock ◽  
...  
Keyword(s):  
Oxidative Addition ◽  
Mechanistic Studies ◽  
Carbene Complex ◽  
Catalytic Amination

On the Reactivity of mRNA Caps: C-H Oxidative Addition of 7-Methylguanosine to Pt(0)

2019 ◽  
Author(s):  
Maria Ines Leitao ◽  
Carmen Gonzalez ◽  
Zuzanna Filipiak ◽  
Ana Petronilho
Keyword(s):  
Oxidative Addition ◽  
Carbene Complex ◽  
Proton Loss

<p>7-methylguanosine, the so-called mRNA cap 0 bears a very labile C8-H bond, due to the formation of an ylide/N-heterocyclic carbene, upon proton loss. The reaction of 7-methylguanosine with Pt(PPh3)4, via C-H oxidative addition, yields a hydrido–PtII carbene complex and this reactivity can be extrapolated to 7,9-dimethylguanine. </p>

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 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.

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