31158-32-4Relevant academic research and scientific papers
N-Methylphenothiazine S-Oxide Enabled Oxidative C(sp2)–C(sp2) Coupling of Boronic Acids with Organolithiums via Phenothiaziniums
Yoshida, Tatsuki,Honda, Yuki,Morofuji, Tatsuya,Kano, Naokazu
, p. 9664 - 9668 (2021/12/17)
Herein, we report the development of a transition-metal-free oxidative C(sp2)–C(sp2) coupling of readily available boronic acids and organolithiums via phenothiazinium ions. Various biaryl, styrene, and diene derivatives were obtained using this reaction system. The key to this process is N-methylphenothiazine S-oxide (PTZSO), which allows efficient conversion of boronic acids to phenothiazinium ions. The mechanism of phenothiazinium formation using PTZSO was investigated using theoretical calculations and experiments, which provided insight into the unique reactivity of PTZSO.
Less hindered ligands give improved catalysts for the nickel catalysed Grignard cross-coupling of aromatic ethers
Harkness, Gavin J.,Clarke, Matthew L.
, p. 328 - 334 (2018/01/12)
The challenging reaction of unactivated ortho-substituted aromatic ethers with Grignard reagents has been found to be most effectively catalysed using nickel complexes of less sterically hindered ligands. Air stable, cheap, commercially available [NiCl2(PnBu3)2] stands out as an improved catalyst for this type of transformation. The improved results with this catalyst even extend to some couplings of a more activated substrate when examined at higher temperatures and at catalyst loadings down to 0.1 mol%. Unusual induction periods in these latter reactions have been related to the by-product magnesium salts acting as co-catalysts.
Air-Stable Dinuclear Iodine-Bridged Pd(I) Complex - Catalyst, Precursor, or Parasite? the Additive Decides. Systematic Nucleophile-Activity Study and Application as Precatalyst in Cross-Coupling
Aufiero, Marialuisa,Scattolin, Thomas,Proutière, Fabien,Schoenebeck, Franziska
supporting information, p. 5191 - 5195 (2015/11/09)
Dinuclear Pd(I) complexes were recently shown to potentially adopt various possible roles in catalysis, being capable of functioning as catalyst via dinuclear catalysis cycles, precatalyst for Pd(0), or inhibitor. This report examines the factors that control the mechanistic role in catalysis. Our data suggest that the transformation to Pd(0) occurs via nucleophile-induced fragmentation of Pd(I)-Pd(I). A systematic study examining the nucleophilicity of additive versus activity was undertaken that revealed the minimum nucleophilicity necessary to activate two structurally very similar Pd(I) dimers, [Pd(μ-X)(PtBu3)]2 (X = I or Br). While the more labile bromine-bridged Pd(I) dimer is converted to Pd(0) with nucleophiles N ≥ 10.5, the iodine-bridged analogue requires N ≥ 16.1 (N according to Mayrs scale). Too strong nucleophiles generate a high concentration of unstable monoligated Pd(0) rapidly, leading to Pd loss (i.e., Pd black). On the other hand, careful tuning of nucleophilicity allows for a controlled release of well-defined Pd(0) species. These insights have led to the first application of the air-stable and previously thought unreactive iodine-bridged dimer [Pd(μ-I)(PtBu3)]2 as a precatalyst for monoligated Pd(0) in cross-coupling reactions. The reactions were performed without exclusion of oxygen-all reagents were handled in air without special precautions. Highly efficient Kumada couplings of aryl iodides and bromides were achieved in 5 min at room temperature.
Iron-catalyzed coupling of aryl sulfamates and aryl/vinyl tosylates with aryl grignards
Agrawal, Toolika,Cook, Silas P.
supporting information, p. 5080 - 5083 (2014/12/11)
The iron-catalyzed coupling of aryl sulfamates and tosylates with aryl Grignard reagents is reported for the first time. The methodology employs air-stable, low-cost FeF3·3H2O and the N-heterocyclic carbene ligand IPr·HCl as the preligand to form a long-lived catalyst upon treatment with aryl Grignards. The reaction provides a range of cross-coupled products in good-to-excellent yields. In contrast to previous reports with aryl chlorides, these reactions proceed with low levels of Grignard homocoupling regardless of the iron source.
Dramatic effect of the gelling cation on the catalytic performances of alginate-supported palladium nanoparticles for the Suzuki-Miyaura reaction
Chtchigrovsky, Melanie,Lin, Yi,Ouchaou, Kahina,Chaumontet, Manon,Robitzer, Mike,Quignard, Francoise,Taran, Frederic
experimental part, p. 1505 - 1510 (2012/07/31)
This work describes the preparation and characterization of a library of alginate-supported palladium nanoparticles together with their catalytic capabilities to promote the Suzuki-Miyaura reaction. Using the chelating properties of the carboxylate functions of the alginate matrix a series of Ca, Ba, Mn, Zn, Ni, Ce, Cu, and Co alginate gels were first prepared and then reacted with Pd2+ salts. Partial exchange of metal cations followed by Pd reduction into palladium nanoparticles and supercritical CO2 drying generated a panel of bimetallic alginate aerogels. Physical characterizations of these materials showed a significant influence of both the gelling metal nature and the Pd loading on surface areas and nanoparticles size. A comparative study of the catalytic performances of these heterogeneous catalytic systems is then reported for the Suzuki-Miyaura reaction. This study highlighted the superior performances of palladium nanoparticles supported on copper-alginate aerogels. This heterogeneous catalyst showed high catalytic activities as illustrated by a TOF value of 10 s-1 and a TON value close to 106. The robustness of the catalyst allowed several reuses with no significant loss of activity or metal leaching.
A recyclable triethylammonium ion-tagged diphenylphosphine palladium complex for the Suzuki-Miyaura reaction in ionic liquids
Lombardo, Marco,Chiarucci, Michel,Trombini, Claudio
experimental part, p. 574 - 579 (2010/04/23)
Suzuki-Miyaura reactions of aryl bromides and arylboronic acids proceed in good to excellent yields in a pyrrolidinium ionic liquid by using a preformed air stable and easily handled triethylammonium-tagged diphenylphosphine palladium(ii) complex (2). The reaction requires short reaction times and mild temperature conditions and does not show any tendency towards the formation of palladium black. After extraction of the product, the catalyst containing ionic liquid phase is easily recycled for 6 times, with no significant loss of catalytic activity.
Synthesis and applications of a new palladacycle as a high active catalyst in the Suzuki couplings
Joshaghani, Mohammad,Daryanavard, Marzieh,Rafiee, Ezzat,Nadri, Shirin
, p. 3135 - 3140 (2008/12/22)
The reaction of biphenyl-based phosphine P(o-C6H4Me)Ph2 (1) with Pd(OAc)2 in toluene affords the air and water stable palladacycle (2) as a binuclear compound which has been characterized by multi-nuclear NMR spectroscopy and elemental analysis as a mixture of cis and trans isomers with relative intensity of 1:3, respectively. This palladacycle is a highly efficient catalyst precursor for the coupling of aryl boronic acids and aryl halides. Both activated and deactivated aryl bromides and chlorides are efficiently coupled in the presence of 2 to furnish the corresponding cross-coupled products in excellent yields, and a wide variety of functional groups are tolerated in aryl halides. This methodology has also been extended for the coupling of bromoarylphosphines and bromoarylphosphine oxides with aryl boronic acids for the generation of hindered corresponding products.
Halogen Exchange Between Aryl Grignarg Reagents and Aryl Halides in the Presence of Nickel(II) Chloride
Wang, Jiping,Pomerantz, Martin
, p. 2571 - 2574 (2007/10/02)
A unique halogen exchange reaction between aryl Grignard reagents and aryl halides, which occured during an attempted cross-coupling reaction using non-ligated nickel(II) chloride as a catalyst, has been observed.The halogen exchange takes place between arylmagnesium iodides and aryl bromides but not between arylmagnesium bromides and aryl chlorides.
Photocatalysis of Oligo(p-phenylenes). Photoreductive Production of Hydrogen and Ethanol in Aqueous Triethylamine
Matsuoka, Shinjiro,Fujii, Hiroyuki,Yamada, Taisuke,Pac, Chyongjin,Ishida, Akito,et al.
, p. 5802 - 5808 (2007/10/02)
Oligo(p-phenylenes) (OPP-n), p-terphenyl (OPP-3) to p-sexiphenyl (OPP-6), catalyze water-reductive H2 formation and reduction of concomitantly formed acetaldehyde to ethanol upon irradiation of heterogeneous suspensions in aqueous organic solution in the presence of triethylamine (TEA) and RuCl3.Colloidal Ru0 is photoformed in situ to work as an electron relay.The activity of OPP-n increases with the number of phenylene units except for the cases of OPP-3 and of the alkylated derivatives, where the net photocatalytic activities are higher, mainly due to the effective homogeneous catalysis, since their solubilities in the solvents employed are significantly larger.The homogeneous catalysis of OPP-3 leads not only to H2 evolution but also to effective formation of ethanol in the absence of colloidal Ru0, being accompanied by photo-Birch reduction of OPP-3.Dynamics studies of OPP-3 reveal that photocatalysis should be initiated by formation of the excited singlet state of OPP-3 (1OPP-3*, which is reductively quenched by TEA at a rate controlled by diffusion to produce the OPP-3 radical anion (OPP-3.-) and the TEA radical cation (TEA.+).From laser flash photolysis and pulse radiolysis experiments, it is concluded that electron transfer from OPP-3.- leads to effective reduction of water to H2 catalyzed by Ru0 colloid.Furthermore, it is confirmed that OPP-3.- gives electrons directly to acetaldehyde without any electron relays like colloidal metals, resulting in the formation of ethanol.During photocatalysis, OPP-3 itself undergoes photo-Birch reduction to some extent.
