398-23-2Relevant academic research and scientific papers
CpRhIII-Catalyzed Allyl-Aryl Coupling of Olefins and Arylboron Reagents Enabled by C(sp3)-H Activation
Knecht, Tobias,Pinkert, Tobias,Dalton, Toryn,Lerchen, Andreas,Glorius, Frank
, p. 1253 - 1257 (2019)
Herein, we present a mild CpRhIII-catalyzed Suzuki-Miyaura-type allyl-aryl coupling of readily accessible arylboron reagents with a broad range of olefins. Allylic arylation was achieved without the need for prefunctionalized alkenes, and the general Heck-type reactivity between olefins and arenes was not observed. Mechanistic studies indicate that the reaction was enabled through the fast generation of a RhIII-allyl species via undirected C(sp3)-H activation. Moreover, the developed protocol was applied to the highly concise synthesis of the anti-inflammatory drug flurbiprofen.
Tailored quinones support high-turnover Pd catalysts for oxidative C-H arylation with O2
Salazar, Chase A.,Flesch, Kaylin N.,Haines, Brandon E.,Zhou, Philip S.,Musaev, Djamaladdin G.,Stahl, Shannon S.
, p. 1454 - 1460 (2020)
Palladium(II)-catalyzed carbon-hydrogen (C-H) oxidation reactions could streamline the synthesis of pharmaceuticals, agrochemicals, and other complex organic molecules. Existing methods, however, commonly exhibit poor catalyst performance with high palladium (Pd) loading (e.g., 10 mole %) and a need for (super)stoichiometric quantities of undesirable oxidants, such as benzoquinone and silver(I) salts. The present study probes the mechanism of a representative Pd-catalyzed oxidative C-H arylation reaction and elucidates mechanistic features that undermine catalyst performance, including substrate-consuming side reactions and sequestration of the catalyst as an inactive species. Systematic tuning of the quinone cocatalyst overcomes these deleterious features. Use of 2,5-di-tert-butyl-p-benzoquinone enables efficient use of molecular oxygen as the oxidant, high reaction yields, and >1900 turnovers by the Pd catalyst.
Water as Solvent for Nickel-2,2′-Bipyridine-Catalysed Electrosynthesis of Biaryls from Haloaryls
Raynal, Frederic,Barhdadi, Rachid,Perichon, Jacques,Savall, Andre,Troupel, Michel
, p. 45 - 49 (2002)
Reductive homocoupling of aryl halides into biaryls was achieved by electrolysis of aqueous emulsions, either in an undivided cell fitted with a sacrificial anode, or in a divided diaphragm cell, and in the presence of nickel-2,2′-bipyridine as catalyst. Reactions were also run in a filter-press cell.
Reactivity studies of cationic Au(III) difluorides supported by N ligands
Sharp-Bucknall, Lachlan,Barwise, Lachlan,Bennetts, Jason D.,Albayer, Mohammad,Dutton, Jason L.
, p. 3344 - 3351 (2020)
The reactivity of difluoro Au(III) cations supported by pyridine or imidazole ligands is reported. The Au(III)?F bond is found to be susceptible to metathesis by TMS reagents and reagents bearing acidic protons such as H?CC?Ph and HOAc. In the last case the reactions are slower than analogous reactions reported by other groups, where strong trans donors are present opposite the Au?F bond. This, coupled with the inability to effect metathesis on only one Au?F bond in our system, indicates that the trans effect is a key consideration in Au?F chemistry.
Palladium-Catalyzed (4 + 4) Annulation of Silacyclobutanes and 2-Iodobiarenes to Eight-Membered Silacycles via C-H and C-Si Bond Activation
Zhu, Ming-Hui,Zhang, Xiao-Wen,Usman, Muhammad,Cong, Hengjiang,Liu, Wen-Bo
, p. 5703 - 5708 (2021)
Construction of eight-membered silacycles via Pd-catalyzed (4 + 4) annulation of silacyclobutanes and 2-iodobiphenyl derivatives is described. This strategy involves direct C-H and C-Si bond activation followed by a ring annulation and features low catalyst loading, ligand-free conditions, and readily available starting materials. Mechanistic studies revealed the involvement of five-membered palladacycle species in the reaction.
Ligand promoted palladium-catalyzed homo-coupling of arylboronic acids
Wong, Man Shing,Zhang, Xiao Ling
, p. 4087 - 4089 (2001)
Palladium-catalysed homo-coupling of arylboronic acids can be promoted by phosphine or phosphite ligands thereby offering a simple and efficient protocol for the synthesis of symmetrical bi-aryl molecules and their higher homologues.
Pre-transmetalation intermediates in the Suzuki-Miyaura reaction revealed: The missing link
Thomas, Andy A.,Denmark, Scott E.
, p. 329 - 332 (2016)
Despite the widespread application of Suzuki-Miyaura cross-coupling to forge carbon-carbon bonds, the structure of the reactive intermediates underlying the key transmetalation step from the boron reagent to the palladium catalyst remains uncertain. Here we report the use of low-temperature rapid injection nuclear magnetic resonance spectroscopy and kinetic studies to generate, observe, and characterize these previously elusive complexes. Specifically, this work establishes the identity of three different species containing palladium-oxygen-boron linkages, a tricoordinate boronic acid complex, and two tetracoordinate boronate complexes with 2:1 and 1:1 stoichiometry with respect to palladium. All of these species transfer their boron-bearing aryl groups to a coordinatively unsaturated palladium center in the critical transmetalation event.
Palladium-catalyzed aryl group transfer from triarylphosphines to arylboronic acids
Enright, Dale R.,Gogate, Akash R.,Smoliakova, Irina P.,Vasireddy, Purna C. R.
, (2021/11/11)
A study of Pd-catalyzed arylation of arylboronic acids with triarylphosphines is presented. Various parameters of this transformation, such as the oxygen presence, choice of solvent, temperature, palladium source, bases and oxidants, were tested and the optimal conditions of the aryl transfer were determined. The effect of electron-withdrawing and electron-donating substituents on the aryl groups of both reactants was also investigated. The unusual transfer of the acetate group from Pd(OAc)2 to p-nitrophenylboronic acid in the presence of PAr3 is reported. A plausible mechanism of the Pd-catalyzed aryl group transfer from PAr3 to the arylboronic acid is proposed.
Competitive gold/nickel transmetalation
Austen, Brady J. H.,Demchuk, Mitchell J.,Drover, Marcus W.,Nelson, David J.,Zurakowski, Joseph A.
supporting information, p. 68 - 71 (2021/12/29)
Transmetalation is a key method for the construction of element-element bonds. Here, we disclose the reactivity of [NiII(Ar)(I)(diphosphine)] compounds with arylgold(i) transmetalating agents, which is directly relevant to cross-coupling catalysis. Both aryl-for-iodide and unexpected aryl-for-aryl transmetalation are witnessed. Despite the strong driving force expected for Au-I bond formation, aryl scrambling can occur during transmetalation and may complicate the outcomes of attempted catalytic cross-coupling reactions.
Palladium nanoparticle supported on nitrogen-doped porous carbon: Investigation of structural properties and catalytic activity on Suzuki–Miyaura reactions
Bu?day, Nesrin,Alt?n, Serdar,Ya?ar, Sedat
, (2021/08/25)
Novel palladium-doped nanoporous carbon composite material obtained via thermolysis of amorphous zeolitic imidazolate framework (aZIF) was synthesized and used as an efficient catalyst on Suzuki–Miyaura cross-coupling reactions of aryl bromides. With this developed catalytic system, the Suzuki–Miyaura cross-coupling reaction was accomplished in aqueous solutions, and biaryls were obtained in good to excellent yields in a short reaction time. The APC-750@Pd catalyst was characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Eicroscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Brunauer–Emmett–Teller (BET) analysis tecniques. N-doped porous carbon material (NPC-1000) was synthesized by thermolysis from aZIF. Activated porous carbon material (APC-750) was fabricated via fused at 750°C with KOH from NPC-1000. The APC-750@Pd was obtained as a result of the interaction of APC-750 and PdCl2 in deionized water. The cross-coupling reaction of different aryl bromides with phenylboronic acid was investigated to show the potential of the APC-750@Pd in the Suzuki–Miyaura cross-coupling reactions. The APC-750@Pd catalyst could be recycled at least five times with a 15% loss of catalytic efficiency in this catalytic system.
