Refernces
10.1016/S0022-328X(00)96083-2
The study explores the application of free radicals in the catalytic synthesis of carbon monoxide derivatives, focusing on the reaction of carbon monoxide with organomagnesium compounds in the presence of various carbonyl compounds in tetrahydrofuran. The main product of these reactions was tetrahydrofuranyl-2-ethyl ketone, suggesting a radical mechanism. The reactions were found to be complex, yielding over ten products, including ketones, tertiary alcohols, and hydrocarbons. The study also discusses the potential for other radical sources to facilitate similar reactions, opening new avenues for organic synthesis.
10.1021/ol502014b
The research discusses the development of a palladacycle precatalyst for the aminocarbonylation of (hetero)aryl bromides, which is crucial for the synthesis of pharmaceuticals containing heteroaryl amides. The study presents a method to overcome the limitations of traditional metal-catalyzed transformations, which often suffer from issues like byproduct formation or catalytic turnover inhibition due to the coordinating ability of heterocycles. The researchers used a palladacycle precatalyst to generate a highly active XantPhos-ligated Pd-catalyst, enabling low-temperature aminocarbonylations of (hetero)aryl bromides with good to excellent yields, low catalyst loading, and minimal excess Carbon oxide (CO). The experiments involved the optimization of reaction conditions, including the selection of appropriate precatalysts, solvents, bases, and reaction temperatures, to achieve high conversion rates and yields. The scope of the method was tested with a variety of electron-rich and electron-poor aryl and heteroaryl bromides, demonstrating its versatility and applicability in synthesizing challenging products that are inaccessible or yield low through traditional methods. The analyses used to evaluate the success of the reactions included gas chromatography (GC) yields and isolated yields, as well as spectroscopic data provided in the supporting information.
10.1021/acs.organomet.9b00378
The research focuses on the synthesis and application of fluorene complexes of Group 9 metals, specifically cobalt, rhodium, and iridium, in the context of reductive amination reactions. The study involves the preparation of η6-fluorene cyclopentadienyl complexes (η5-C5R5)M(η6-fluorene)2 (where M = Co, Rh, Ir; R = H, Me) and indenyl derivatives (η5-indenyl)M(η6-fluorene)2 through iodide abstraction using AgSbF6 in the presence of fluorene. The reactivity of these complexes, particularly the rhodium complex 2a2, was investigated, showing a higher lability of the fluorene ligand compared to benzene ligands in similar complexes. The research also explores the mechanism of fluorene elimination through a series of haptotropic rearrangements, supported by DFT calculations. The main experiments involve the synthesis of these complexes, their structural determination by X-ray diffraction, NMR spectroscopy, and the evaluation of their catalytic activity in reductive amination reactions using carbon monoxide as a reducing agent in water as a solvent. The analyses used include 1H and 13C NMR spectroscopy for structural characterization, X-ray diffraction for structural determination, and DFT calculations to understand the bonding interactions and mechanisms involved in the ligand rearrangements and catalytic activity.
10.1016/S0040-4039(00)98115-2
The research focused on the catalytic reactions of disulfides using cobalt carbonyl, aiming to investigate the desulfurization and carbonylation of organic sulfur compounds. The study concluded that aromatic and benzylic disulfides react with carbon monoxide and a catalytic amount of cobalt carbonyl to produce thioesters and carbonyl sulfide. In the presence of t-butyl peroxide, high yields of sulfides were obtained. Key chemicals used in the process included cobalt carbonyl (Co2(CO)8), carbon monoxide (CO), and disulfides such as benzyl disulfide and phenyl disulfide, along with solvents like aqueous ethanol and benzene. The reactions resulted in the formation of thioesters and sulfides through a series of steps involving the formation of cobalt complexes and the insertion of carbon monoxide.
10.1021/ja00042a061
The research focuses on the study of metal-CO complexes and their role in catalytic CO oxidation, as well as the development of new synthetic routes to such complexes. The purpose of the study was to investigate the reaction of toluene solutions of specific metal carbonyl complexes with oxygen, leading to the formation of CO2 complexes in high yields. The conclusions drawn from the research not only provided new insights into the possible role of metal-CO complexes in catalytic CO oxidation but also offered a convenient synthetic route to these complexes. Key chemicals used in the process included (q5-C5H4CH3)2Nb(CO)R (1), O2, and the resulting complexes (q5-C5H4CH3)2Nb(q2-CO2)R (2). Additionally, the research involved isotopic labeling with 18O2 to trace the origin of the additional oxygen atom in the complexes, and the use of IR spectroscopy to monitor the progress of the reactions and the distribution of the isotopic label.
10.1021/ja992125d
The research focuses on the development of a new radical cascade methodology for synthesizing vicinal singly and doubly acylated oxime ethers, which are potential precursors for vicinal di- and tricarbonyl compounds. The purpose of this study was to overcome the challenges in synthesizing these compounds through the coupling of multiple radical one-carbon (C1) synthons, such as carbon monoxide (CO) and sulfonyl oxime ethers. The researchers successfully demonstrated that a three-component coupling reaction involving RX, CO, and phenylsulfonyl oxime ether B, mediated by allyltributyltin and initiated by AIBN, could yield R-acyl-substituted aldoximes with high efficiency. The study concluded that this new radical cascade strategy not only expands the scope of radical C1 chemistry but also offers a versatile synthetic methodology for incorporating multiple C1 units into important nitrogen-containing heterocycles. The chemicals used in the process include phenylsulfonyl oxime ether B, allyltributyltin, AIBN, alkyl iodides, and carbon monoxide, among others.
10.1021/ja00207a011
The research investigates the carbon monoxide (CO) cleavage mechanism by the tantalum siloxide complex (silox)3Ta, focusing on the formation of a dicarbide complex and the intermediate species involved. The study aims to understand the fundamental steps of CO dissociation and its relevance to the Fischer-Tropsch process, which converts synthesis gas into hydrocarbons. Key chemicals used include (silox)3Ta, CO, and various solvents like benzene and toluene. The researchers discovered that (silox)3Ta binds CO to form unstable intermediates, which can aggregate or disproportionate to yield a red precipitate and eventually a dicarbide complex. They also identified a ketenylidene intermediate and elucidated its formation pathway. The study concludes that only two tantalum centers are necessary to cleave one CO molecule, providing insights into the potential for homogeneous systems to model heterogeneous Fischer-Tropsch catalysts.
10.1021/om9008235
This research investigates the synthesis and mechanism of nonalternating ethene/carbon monoxide copolymers using a neutral palladium catalyst with a phosphine-sulfonate ligand. The purpose is to produce copolymers with a wide range of carbon monoxide incorporation (1-50 mol%) while maintaining processability, which is challenging with conventional catalysts that produce strictly alternating copolymers. The study finds that the small difference in binding affinities of ethene and carbon monoxide to the palladium complex, determined to be ～50:1 by NMR spectroscopy, plays a crucial role in the copolymer composition. Additionally, decarbonylation significantly contributes to nonalternation. Unlike traditional cationic palladium complexes, the neutral phosphine-sulfonate system disfavors Pd-O chelate formation, facilitating ethene coordination and insertion. The research concludes that controlling the degree of carbon monoxide incorporation is possible by adjusting the monomer feed ratio and reaction temperature, and it provides insights into the kinetic and thermodynamic parameters governing the nonalternating copolymerization process.
10.1016/0022-328X(88)80531-X
The study investigates the reactions of pentacarbonyl(tetrafluoroborato)rhenium, (OC)5ReFBF4, with various isocyanides to form ionic complexes [(OC)5ReCNR]+BF4 - (1), where R represents different substituents such as CMe3, C6H11, Ph, CH2CO2Et, and CH2SO2C6H4Me. The reactivity of these complexes towards nucleophiles like N3-, OH-, OR-, NH2R, and NHR2 is examined. The study reveals that nucleophilic attacks on the carbon monoxide ligand or the isocyanide ligand lead to the formation of various products, including hydroxycarbonyl complexes, carbamoyl complexes, and dicarbamoyl-bridged complexes, depending on the specific substituents and nucleophiles involved. The study also includes the synthesis and characterization of these complexes, providing insights into their structures and properties through techniques such as IR spectroscopy and X-ray crystallography.
10.1021/om020644a
The research focuses on the synthesis, photochemistry, and structural analysis of three isomeric diiron complexes containing Si2C2 frameworks, specifically FpCH2SiR2SiR2CH2Fp (where Fp = (η5-C5H5)Fe(CO)2 and R = Me or Ph). The study involves the photolysis of these complexes, leading to the formation of 1,3-disilacyclobutanes and Fp2, with the process being intramolecular and stereospecific. The experiments utilized various reactants, including Fp derivatives, silyl halides, and transition metals, and were conducted under controlled conditions such as vacuum and argon atmosphere. Transition metals and ligands such as carbon monoxide (CO). Analytical techniques employed included nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, and elemental analysis to characterize the intermediates and products. The research also explored the potential mechanisms for the formation of disilacyclobutanes, suggesting the involvement of bis(silene-iron) intermediates and oxidative addition processes.
