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.
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.
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
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.
Synthesis of arylboronates via the Pd-catalyzed desulfitative coupling reaction of sodium arylsulfinates with bis(pinacolato)diboron
Qiu, Di,Li, Songyi,Yue, Guanglu,Mao, Jinshan,Xu, Bei,Yuan, Xinyu,Ye, Fei
, (2021/11/04)
The desulfitative borylation reaction of sodium arylsulfinates with bis(pinacolato)diboron or bis(neopentylglycolato)diboron under palladium catalysis has been developed, allowing selective C-B bond formation to give arylboronates with a range of functional groups in moderate to good yields under mild reaction conditions. A gram-scale preparation as well as the cascade Suzuki-Miyaura cross-coupling of arylboronates demonstrated the potential practical utility in organic synthesis.
Nickel-Catalyzed Ipso-Borylation of Silyloxyarenes via C-O Bond Activation
Pein, Wesley L.,Wiensch, Eric M.,Montgomery, John
supporting information, (2021/06/28)
The conversion of silyloxyarenes to boronic acid pinacol esters via nickel catalysis is described. In contrast to other borylation protocols of inert C-O bonds, the method is competent in activating the carbon-oxygen bond of silyloxyarenes in isolated aromatic systems lacking a directing group. The catalytic functionalization of benzyl silyl ethers was also achieved under these conditions. Sequential cross-coupling reactions were achieved by leveraging the orthogonal reactivity of silyloxyarenes, which could then be functionalized subsequently.
Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
K?nig, Burkhard,Wang, Hua,Wang, Shun
, p. 1653 - 1665 (2021/06/17)
Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
