25255-90-7Relevant academic research and scientific papers
Benzoate Cyclometalation Enables Oxidative Addition of Haloarenes at a Ru(II) Center
Simonetti, Marco,Kuniyil, Rositha,Macgregor, Stuart A.,Larrosa, Igor
supporting information, p. 11836 - 11847 (2018/09/29)
The first Ru(II)-catalyzed arylation of substrates without a directing group was recently developed. Remarkably, this process only worked in the presence of a benzoate additive, found to be crucial for the oxidative addition step at Ru(II). However, the exact mode of action of the benzoate was unknown. Herein, we disclose a mechanistic study that elucidates the key role of the benzoate salt in the C-H arylation of fluoroarenes with aryl halides. Through a combination of rationally designed stoichiometric experiments and DFT studies, we demonstrate that the aryl-Ru(II) species arising from initial C-H activation of the fluoroarene undergoes cyclometalation with the benzoate to generate an anionic Ru(II) intermediate. The enhanced lability of this intermediate, coupled with the electron-rich anionic Ru(II) metal center renders the oxidative addition of the aryl halide accessible. The role of an additional (NMe4)OC(CF3)3 additive in facilitating the overall arylation process is also shown to be linked to a shift in the C-H pre-equilibrium associated with benzoate cyclometalation.
Mechanistic studies of the O2-dependent aliphatic carbon-carbon bond cleavage reaction of a nickel enolate complex
Berreau, Lisa M.,Borowski, Tomasz,Grubel, Katarzyna,Allpress, Caleb J.,Wikstrom, Jeffrey P.,Germain, Meaghan E.,Rybak-Akimova, Elena V.,Tierney, David L.
experimental part, p. 1047 - 1057 (2011/05/05)
The mononuclear nickel(II) enolate complex [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph] ClO4 (I) was the first reactive model complex for the enzyme/substrate (ES) adduct in nickel(II)-containing acireductone dioxygenases (ARDs) to be reported. In this contribution, the mechanism of its O 2-dependent aliphatic carbon-carbon bond cleavage reactivity was further investigated. Stopped-flow kinetic studies revealed that the reaction of I with O2 is second-order overall and is ～ 80 times slower at 25 °C than the reaction involving the enolate salt [Me4N][PhC(O) C(OH)C(O)Ph]. Computational studies of the reaction of the anion [PhC(O)C(OH)C(O)Ph]- with O2 support a hydroperoxide mechanism wherein the first step is a redox process that results in the formation of 1,3-diphenylpropanetrione and HOO-. Independent experiments indicate that the reaction between 1,3-diphenylpropanetrione and HOO- results in oxidative aliphatic carbon-carbon bond cleavage and the formation of benzoic acid, benzoate, and CO:CO2 ( ～ 12:1). Experiments in the presence of a nickel(II) complex gave a similar product distribution, albeit benzil [PhC(O)C(O)Ph] is also formed, and the CO:CO2 ratio is ～ 1.5:1. The results for the nickel(II)-containing reaction match those found for the reaction of I with O2 and provide support for a trione/HOO- pathway for aliphatic carbon-carbon bond cleavage. Overall, I is a reasonable structural model for the ES adduct formed in the active site of Ni"ARD. However, the presence of phenyl appendages at both C(1) and C(3) in the [PhC(O)C(OH)C(O)Ph]- anion results in a reaction pathway for O2-dependent aliphatic carbon-carbon bond cleavage (via a trione intermediate) that differs from that accessible to C(1)- H acireductone species. This study, as the first detailed investigation of the O2 reactivity of a nickel(II) enolate complex of relevance to Ni"ARD, provides insight toward understanding the chemical factors involved in the O2 reactivity of metal acireductone species.
Backscattering Interferometry: An alternative approach for the study of hydrogen bonding interactions in organic solvents
Pesciotta, Esther N.,Bornhop, Darryl J.,Flowers, Robert A.
supporting information; experimental part, p. 2654 - 2657 (2011/06/25)
Intermolecular interactions involving hydrogen bonds are responsible for catalysis and recognition. Traditional methods used to study hydrogen-bonding interactions are generally limited to relatively large volumes and high substrate concentrations. Backscattering Interferometry (BSI) provides a microfluidic platform to study these interactions in nonaqueous media at micromolar to nanomolar concentrations in picoliter volumes by monitoring changes in the refractive index.
POSITIVE RESIST COMPOSITION AND PATTERNING PROCESS
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, (2010/04/23)
A positive resist composition comprises (A) a resin component which becomes soluble in an alkaline developer under the action of an acid and (B) an acid generator. The resin (A) is a polymer comprising recurring units containing a non-leaving hydroxyl group represented by formula (1) wherein R1 is H, methyl or trifluoromethyl, X is a single bond or methylene, m is 1 or 2, and the hydroxyl group attaches to a secondary carbon atom. The composition is improved in resolution when processed by lithography.
Therapeutic delivery of carbon monoxide
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Page/Page column 15, (2010/05/13)
Compounds, pharmaceutical compositions and methods for the therapeutic delivery of carbon monoxide to humans and other mammals that employ Mn complexes having CO ligands, and additional halogen, monodentate and/or bidentate ligands, wherein the additional ligands do not occupy trans positions relative to each other.
Amination of Nitrobenzene via Nucleophilic Aromatic Substitution for Hydrogen: Direct Formation of Aromatic Amide Bonds
Stern, Michael K.,Cheng, Brian K.
, p. 6883 - 6888 (2007/10/02)
The first example of the direct formation of aromatic amide bonds via nucleophilic aromatic substitution for hydrogen is described.Thus, the reaction of benzamide, tetramethylammonium hydroxide dihydrate, and nitrobenzene under anaerobic conditions generates N-(4-nitrophenyl)benzamide (1) (98percent) and azoxybenzene (30percent) in isolated yields.In addition, other substituted benzamides and aliphatic amides are shown to function as nucleophiles in this reaction.A mechanism that is consistent with the simultaneous formation of anilide products and azoxybenzene which requires the oxidation of ?-complex intermediates by nitrobenzene initially generating nitrobenzene radical anions is proposed.By contrast, when the reaction is run under aerobic conditions, the formation of azoxybenzene is completely inhibited due to the trapping of nitroarene radicals by O2.The ability to prepare 1 in high yield and regioselectivity affords a novel route for the direct amination of nitrobenzene that does not require halogenated intermediates or auxiliary leaving groups.Accordingly, treatment of 1 with methanolic ammonia results in the aminolysis of the amide bond producing 4-nitroaniline and regenerates benzamide.
