325142-84-5Relevant academic research and scientific papers
Palladium-catalyzed borylation of aryl bromides and chlorides using phosphatrioxa-adamantane ligands
Lamola, Jairus L.,Moshapo, Paseka T.,Holzapfel, Cedric W.,Christopher Maumela, Munaka
supporting information, (2021/12/13)
Catalysts based on the combination of Pd(OAc)2 and the electron-deficient phosphatrioxa-adamantane ligands are described for borylation of aryl bromides and chlorides. Catalytic evaluation of a small library of phosphatrioxa-adamantane ligands provided some insights on the preferred ligand steric profile for borylation reactions. The corresponding aryl boronate esters were accessed under mild conditions (25–70 °C) and isolated in high yields (up to 96%).
Mono-Phosphine Metal-Organic Framework-Supported Cobalt Catalyst for Efficient Borylation Reactions
Akhtar, Naved,Antil, Neha,Balendra,Begum, Wahida,Chauhan, Manav,Gupta, Poorvi,Kumar, Ajay,Malik, Jaideep,Manna, Kuntal,Newar, Rajashree
supporting information, (2022/03/15)
We report a metal-organic framework (MOF) supported monoligated phosphine-cobalt complex, which is an active heterogeneous catalyst for aromatic C?H borylation and alkene hydroboration. The mono(phosphine)-Co catalyst (MOF?P?Co) was prepared by metalation of a porous triarylphosphine-functionalized MOF (MOF?P) with CoCl2 followed by activation with NaEt3BH. The MOF catalyst has a broad substrate scope with excellent functional group tolerance to afford arene- and alkyl-boronate esters in excellent yields and selectivity. MOF?P?Co gave a turnover number (TON) of 30,000 and could be recycled and reused at least 13 times in arene C?H borylation. Importantly, the attempt to prepare the homogeneous control (Ph3P?Co) using triphenylphosphine was unsuccessful due to the facile disproportionation reactions or intermolecular ligand exchanges in the solution. In contrast, the site isolation of the active mono(phosphine)-Co species within the MOF affords the robust and coordinatively unsaturated metal complexes, allowing to explore their catalytic properties and the reaction mechanism.
Unreactive C-N Bond Activation of Anilines via Photoinduced Aerobic Borylation
Ji, Shuohan,Qin, Shengxiang,Yin, Chunyu,Luo, Lu,Zhang, Hua
supporting information, p. 64 - 68 (2021/12/27)
Unreactive C-N bond activation of anilines was achieved by photoinduced aerobic borylation. A diverse range of tertiary and secondary anilines were converted to aryl boronate esters in moderate to good yields with wide functional group tolerance under simple and ambient photochemical conditions. This transformation achieved the direct and facile C-N bond activation of unreactive anilines, providing a convenient and practical route transforming widely available anilines into useful aryl boronate esters.
Arene borylation through C–H activation using Cu3(BTC)2 as heterogeneous catalyst
Dhakshinamoorthy, Amarajothi,García, Cristina Vallés,Concepcion, Patricia,Garcia, Hermenegildo
, p. 212 - 217 (2020/07/06)
C–H borylation by diborane is an important process to access organoboron compounds. Noble metals, including Ir and Rh-based complexes either in the form of homogeneous or heterogeneous catalysts, have been reported to promote arene C–H borylation. Recently, metal organic frameworks (MOFs) having Ir and Co as active sites have been used as catalysts, but they require co-catalysts. In the present study, commercially available Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) MOF is reported as an effective catalyst to promote borylation of arenes through C–H activation employing bis(pinacolato)diboron (1) as reagent leading to benzylic and aromatic borylation products. Interestingly, other related MOFs like MIL-101(Cr) and Al(OH)(BDC) (BDC: 1,4-benzenedicarboxylate) do not exhibit catalytic activity under identical conditions. Mechanistic studies using in-situ IR spectroscopy reveal that Cu ions play a crucial role in activating the arene and B–B bond in 1.
Catalytic Boration of Alkyl Halides with Borane without Hydrodehalogenation Enabled by Titanium Catalyst
Wang, Xianjin,Cui, Penglei,Xia, Chungu,Wu, Lipeng
supporting information, p. 12298 - 12303 (2021/05/07)
An unprecedented and general titanium-catalyzed boration of alkyl (pseudo)halides (alkyl-X, X=I, Br, Cl, OMs) with borane (HBpin, HBcat) is reported. The use of titanium catalyst can successfully suppress the undesired hydrodehalogenation products that prevail using other transition-metal catalysts. A series of synthetically useful alkyl boronate esters are readily obtained from various (primary, secondary, and tertiary) alkyl electrophiles, including unactivated alkyl chlorides, with tolerance of other reducing functional groups such as ester, alkene, and carbamate. Preliminary studies on the mechanism revealed a possible radical reaction pathway. Further extension of our strategy to aryl bromides is also demonstrated.
Sequential Ir/Cu-Mediated Method for the Meta-Selective C-H Radiofluorination of (Hetero)Arenes
Wright, Jay S.,Sharninghausen, Liam S.,Preshlock, Sean,Brooks, Allen F.,Sanford, Melanie S.,Scott, Peter J. H.
supporting information, p. 6915 - 6921 (2021/05/29)
This article describes a sequential Ir/Cu-mediated process for the meta-selective C-H radiofluorination of (hetero)arene substrates. In the first step, Ir-catalyzed C(sp2)-H borylation affords (hetero)aryl pinacolboronate (BPin) esters. The intermediate organoboronates are then directly subjected to copper-mediated radiofluorination with [18F]tetrabutylammonium fluoride to afford fluorine-18 labeled (hetero)arenes in high radiochemical yield and radiochemical purity. This entire process is performed on a benchtop without Schlenk or glovebox techniques and circumvents the need to isolate (hetero)aryl boronate esters. The reaction was automated on a TracerLab FXFN module with 1,3-dimethoxybenzene and a meta-tyrosine derivative. The products, [18F]1-fluoro-3,5-dimethoxybenzene and an 18F-labeled meta-tyrosine derivative, were obtained in 37 ± 5% isolated radiochemical yield and >99% radiochemical purity and 25% isolated radiochemical yield and 99% radiochemical purity, and 0.52 Ci/μmol (19.24 GBq/μmol) molar activity (Am), respectively.
Engaging Ag(0) single atoms in silver(I) salts-mediated C-B and C-S coupling under visible light irradiation
Cui, Enxin,Guo, Lirong,Li, Haibin,Qiao, Dan,Tung, Chen-Ho,Wang, Yifeng
, p. 255 - 263 (2021/09/06)
Silver(I) salts were found active in the borylation and sulfenylation of aryl iodides under visible light irradiation. The optimized borylation protocol using AgF did not need any additive, operated under very mild conditions, and well tolerated a broad scope of substrates and boron sources. Formation of Ag(0) single atoms (AgSAs) during the borylation reactions was examined using high-angle annular dark field aberration-corrected scanning transmission electron microscope (HAADF AC-STEM) and electron paramagnetic resonance (EPR). The activities of the silver(I) salts were affected by the anions and could be associated with their abilities in formation of AgSAs during the reactions. Kinetic studies showed that the deiodination rate was linearly correlated with the loading of AgSAs, and hence AgSAs were the true catalytic centers for the 1e?-reduction of the C-I moieties. The oxidation state of AgSAs kept 0 in both the resting and the working states. A “work-in-tandem” mechanism involving AgSAs as the catalytic centers and AgNPs as the light absorber to achieve the borylation of aryl iodides under visible light irradiation is proposed. The current approach not only provides an alternative system for borylation and sulfenylation of aryl iodides, but also reveals a new activity of silver(I) salts involving AgSAs under visible light irradiation.
Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides
Li, Yafei,Dang, Yan,Li, Dawei,Pan, Huifen,Zhang, Liang,Wang, Li,Cao, Zhu,Li, Yahong
supporting information, p. 482 - 489 (2021/03/01)
A dinucleating bis(β-diketiminate) ligand with a flexible bridge has been employed to synthesize zinc complexes. The ligand, abbreviated H2L (H2L = N-(4-((2-((4-((2,6-diisopropylphenyl)imino)pent-2-en-2-yl)amino)ethyl)imino)pent-2-en-2-yl)-2,6-diisopropylaniline), was deprotonated with ZnEt2 to afford [LZn2Et2] (1). Reactions of 1 with 2 equiv of BnOH and nBuOH, respectively, gave access to [LZn2(OBn)2]·C6H14 (2·C6H14) and [LZn2(OnBu)2] (3). Treatment of 1 with 2 equiv of I2 in THF produced [LZn2I2(THF)2]·2THF (4·2THF). X-ray single-crystal diffraction analyses revealed that they are all heteroleptic bimetallic compounds with two metal centers being chelated by one ligand set. The structurally similar compounds 1 and 4·2THF possess approximate C2 symmetry, with two β-diketiminate units being arrayed in head-to-tail antiparallel mode. Thus, the molecular structures of 1 and 4·2THF exhibit a seesaw-like topology. The structures of 2·C6H14 and 3 are almost identical, in which two zinc atoms are shared by two ZnN2C3 six-membered rings, two Zn2ON2C2 seven-membered rings, and one Zn2O2 four-membered ring. Therefore, the metal cores of 2·C6H14 and 3 display a crownlike topology. All complexes are catalytically active for the borylation of aryl iodides with B2Pin2 (B2Pin2 = 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bis(1,3,2-dioxaborolane). Complex 1 shows higher activity in comparison to 2, 3, and 4·2THF. The borylation reactions catalyzed by 1 could proceed under mild conditions and can be applied to a series of substrates with high functional group generality. This methodology thus represents a novel use of β-diketiminate zinc complexes for C-I borylation.
Evaluation of the role of graphene-based Cu(i) catalysts in borylation reactions
Cid, M. B.,Díaz, Cristina,Franco, Mario,Lamsabhi, Al Mokhtar,Sainz, Raquel,Tortosa, Mariola
, p. 3501 - 3513 (2021/06/06)
Carbon-supported catalysts have been considered as macromolecular ligands which modulate the activity of the metallic catalytic center. Understanding the properties and the factors that control the interactions between the metal and support allows a fine tuning of the catalyzed processes. Although huge effort has been devoted to comprehending binding energies and charge transfer for single atom noble metals, the interaction of graphenic surfaces with cheap and versatile Cu(i) salts has been scarcely studied. A methodical experimental and theoretical analysis of different carbon-based Cu(i) materials in the context of the development of an efficient, general, scalable, and sustainable borylation reaction of aliphatic and aromatic halides has been performed. We have also examined the effect of microwave (MW) radiation in the preparation of these type of materials using sustainable graphite nanoplatelets (GNP) as a support. A detailed analysis of all the possible species in solution revealed that the catalysis is mainly due to an interesting synergetic Cu2O/graphene performance, which has been corroborated by an extensive theoretical study. We demonstrated through DFT calculations at a high level of theory that graphene enhances the reactivity of the metal in Cu2O against the halide derivative favoring a radical departure from the halogen. Moreover, this material is able to stabilize radical intermediates providing unexpected pathways not observed using homogeneous Cu(i) catalysed reactions. Finally, we proved that other common carbon-based supports like carbon black, graphene oxide and reduced graphene oxide provided poorer results in the borylation process.
One-pot synthesis of Ag-Cu-Cu2O/C nanocomposites derived from a metal-organic framework as a photocatalyst for borylation of aryl halide
Annas, Dicky,Bae, Jong-Seong,Hira, Shamim Ahmed,Park, Kang Hyun,Park, Sungkyun,Song, Sehwan
, p. 32965 - 32972 (2021/12/07)
Mixed metal-metal oxide/C (Ag-Cu-Cu2O/C) nanocomposites were synthesized by the heat treatment of a metal-organic framework under a N2 flow using the one-pot synthesis method. The as-prepared nanocomposites were characterized using a range of techniques,
