- Room temperature borylation of arenes and heteroarenes using stoichiometric amounts of pinacolborane catalyzed by iridium complexes in an inert solvent
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Aromatic C-H borylation of arenes and heteroarenes using stoichiometric amounts of pinacolborane was catalyzed by an iridium complex generated from 1/2 [Ir(OMe)(COD)]2 and 4,4′-di-tert-butyl-2,2′-bipyridine at room temperature in hexane and aff
- Ishiyama, Tatsuo,Nobuta, Yusuke,Hartwig, John F.,Miyaura, Norio
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- Recyclable silica-supported iridium bipyridine catalyst for aromatic C-H borylation
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A mesoporous silica (SBA-15)-supported bipyridine iridium complex is prepared by grafting of bipyridine onto the silica support, followed by complexation of an iridium(I) precursor in the presence of HBpin and cyclooctene. Structural analyses by X-ray powder diffraction, nitrogen physisorption, FT-IR, and solid-state NMR spectroscopy demonstrate that the 3-dimensional, hexagonal pore structure of SBA-15 is maintained after the immobilization. In particular, as a heterogeneous catalyst, this silica-supported iridium complex shows moderate to good catalytic activity in the aromatic C-H borylation of a variety of substrates. More importantly, the heterogeneous catalyst is recovered easily and reused repeatedly by simple washing without chemical treatment and exhibits good recycling performance with a modest decrease in the catalytic rate, showing good potential for increasing the overall turnover number of this synthetically useful catalyst.
- Wu, Fengshou,Feng, Yan,Jones, Christopher W.
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Read Online
- Understanding the Activation of Air-Stable Ir(COD)(Phen)Cl Precatalyst for C-H Borylation of Aromatics and Heteroaromatics
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A newly developed robust catalyst [Ir(COD)(Phen)Cl] (A) was used for the C-H borylation of three dozen aromatics and heteroaromatics with excellent yield and selectivity. Activation of the catalyst was identified by the use of catalytic amounts of water, alcohols, etc., when B2pin2 was used in noncoordinating solvents, while for THF catalytic use of HBpin was required. The results were on par with the in situ based expensive system [Ir(OMe)(COD)]2/dtbbpy or Me4Phen.
- Slack, Eric D.,Colacot, Thomas J.
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supporting information
p. 1561 - 1565
(2021/02/20)
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- Metal-organic frameworks containing nitrogen-donor ligands for efficient catalytic organic transformations
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Metal-organic framework (MOFs) compositions based on nitrogen donor-based organic bridging ligands, including ligands based on 1,3-diketimine (NacNac), bipyridines and salicylaldimine, were synthesized and then post-synthetically metalated with metal precursors, such as complexes of first row transition metals. Metal complexes of the organic bridging ligands could also be directly incorporated into the MOFs. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Page/Page column 29; 31-33; 86-88
(2020/06/03)
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- Single-Site Cobalt-Catalyst Ligated with Pyridylimine-Functionalized Metal-Organic Frameworks for Arene and Benzylic Borylation
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We report a highly active single-site heterogeneous cobalt-catalyst based on a porous and robust pyridylimine-functionalized metal-organic frameworks (pyrim-MOF) for chemoselective borylation of arene and benzylic C-H bonds. The pyrim-MOF having UiO-68 topology, constructed from zirconium-cluster secondary building units and pyridylimine-functionalized dicarboxylate bridging linkers, was metalated with CoCl2 followed by treatment of NaEt3BH to give the cobalt-functionalized MOF-catalyst (pyrim-MOF-Co). Pyrim-MOF-Co has a broad substrate scope, allowing the C-H borylation of halogen-, alkoxy-, alkyl-substituted arenes as well as heterocyclic ring systems using B2pin2 or HBpin (pin = pinacolate) as the borylating agent to afford the corresponding arene- or alkyl-boronate esters in good yields. Pyrim-MOF-Co gave a turnover number (TON) of up to 2500 and could be recycled and reused at least 9 times. Pyrim-MOF-Co was also significantly more robust and active than its homogeneous control, highlighting the beneficial effect of active-site isolation within the MOF framework that prevents intermolecular decomposition. The experimental and computational studies suggested (pyrim?-)CoI(THF) as the active catalytic species within the MOF, which undergoes a mechanistic pathway of oxidative addition, turnover limiting σ-bond metathesis, followed by reductive elimination to afford the boronate ester.
- Akhtar, Naved,Antil, Neha,Balendra,Begum, Wahida,Kumar, Ajay,Manna, Kuntal,Newar, Rajashree,Shukla, Sakshi
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supporting information
p. 10473 - 10481
(2020/08/05)
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- Immobilization of Ir(I) complex on covalent triazine frameworks for C–H borylation reactions: A combined experimental and computational study
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Metal-modified covalent triazine frameworks (CTFs) have attracted considerable attention in heterogeneous catalysis due to their strong nitrogen-metal interactions exhibiting superior activity, stability and hence recyclability. Herein, we report on a post-metalation of a bipyridine-based CTFs with an Ir(I) complex for C–H borylation of aromatic compounds. Physical characterization of the Ir(I)-based bipyCTF catalyst in combination with density functional theory (DFT) calculations exhibit a high stabilization energy of the Ir-bipy moiety in the frameworks in the presence of B2Pin2. By using B2Pin2 as a boron source, Ir(I)@bipyCTF efficiently catalyzed the C–H borylation of various aromatic compounds with excellent activity and good recyclability. In addition, XAS analysis of the Ir(I)@bipyCTF gave clear evidence for the coordination environment of the Ir.
- Tahir, Norini,Muniz-Miranda, Francesco,Everaert, Jonas,Tack, Pieter,Heugebaert, Thomas,Leus, Karen,Vincze, Laszlo,Stevens, Christian V.,Van Speybroeck, Veronique,Van Der Voort, Pascal
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p. 135 - 143
(2019/02/12)
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- meta-Nitration of Arenes Bearing ortho/para Directing Group(s) Using C?H Borylation
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Herein, we report the meta-nitration of arenes bearing ortho/para directing group(s) using the iridium-catalyzed C?H borylation reaction followed by a newly developed copper(II)-catalyzed transformation of the crude aryl pinacol boronate esters into the corresponding nitroarenes in a one-pot fashion. This protocol allows the synthesis of meta-nitrated arenes that are tedious to prepare or require multistep synthesis using the existing methods. The reaction tolerates a wide array of ortho/para-directing groups, such as ?F, ?Cl, ?Br, ?CH3, ?Et, ?iPr ?OCH3, and ?OCF3. It also provides regioselective access to the nitro derivatives of π-electron-deficient heterocycles, such as pyridine and quinoline derivatives. The application of this method is demonstrated in the late-stage modification of complex molecules and also in the gram-scale preparation of an intermediate en route to the FDA-approved drug Nilotinib. Finally, we have shown that the nitro product obtained by this strategy can also be directly converted to the aniline or hindered amine through Baran's amination protocol.
- Li, Xuejing,Deng, Xingwang,Coyne, Anthony G.,Srinivasan, Rajavel
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supporting information
p. 8018 - 8023
(2019/05/29)
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- Sterically controlled C-H/C-H homocoupling of arenes: Via C-H borylation
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A mild one-pot protocol for the synthesis of symmetrical biaryls by sequential Ir-catalyzed C-H borylation and Cu-catalyzed homocoupling of arenes is described. The regiochemistry of the biaryl formed is sterically controlled as dictated by the C-H borylation step. The methodology is also successfully extended to heteroarenes. Some of the products obtained by this approach are impossible to obtain via the Ullmann or the Suzuki coupling protocols. Finally, we have shown a one-pot sequence describing C-H borylation/Cu-catalyzed homocoupling/Pd-catalyzed Suzuki coupling to obtain π-extended arene frameworks.
- Pei, Xiaocong,Zhou, Guan,Li, Xuejing,Xu, Yuchen,Panicker, Resmi C.,Srinivasan, Rajavel
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supporting information
p. 5703 - 5707
(2019/06/19)
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- Expanding the Variety of Zirconium-based Inorganic Building Units for Metal–Organic Frameworks
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Two new zirconium-based metal–organic frameworks with the composition [Zr6O4(OH)4(OAc)6(BDC)3] (CAU-26) and [Zr5O4(OH)4(OAc)4(BDC)2] (CAU-27) are
- Leubner, Sebastian,Zhao, Haishuang,Van Velthoven, Niels,Henrion, Micka?l,Reinsch, Helge,De Vos, Dirk E.,Kolb, Ute,Stock, Norbert
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supporting information
p. 10995 - 11000
(2019/07/12)
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- Control Interlayer Stacking and Chemical Stability of Two-Dimensional Covalent Organic Frameworks via Steric Tuning
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Layer stacking and chemical stability are crucial for two-dimensional covalent organic frameworks (2D COFs), but are yet challenging to gain control. In this work, we demonstrate synthetic control of both the layer stacking and chemical stability of 2D COFs by managing interlayer steric hindrance via a multivariate (MTV) approach. By co-condensation of triamines with and without alkyl substituents (ethyl and isopropyl) and a di- or trialdehyde, a family of two-, three-, and four-component 2D COFs with AA, AB, or ABC stacking is prepared. The alkyl groups are periodically appended on the channel walls and their contents, which can be synthetically tuned by the MTV strategy, control the stacking model and chemical stability of 2D COFs by maximizing the total crystal stacking energy and protecting hydrolytically susceptible backbones through kinetic blocking. Specifically, the COFs with higher concentration of alkyl substituents adopt AB or ABC stacking, while lower amount of functionalities leads to the AA stacking. The COFs bearing high concentration of isopropyl groups represent the first identified COFs that can retain crystallinity and porosity in boiling 20 M NaOH solution. After postsynthetic metalation with an iridium complex, the 2,2′-bipyridyl-derived COFs can heterogeneously catalyze C-H borylation of arenes, whereas the COF with isopropyl groups exhibits much higher activity than the COFs with ethyl groups and nonsubstituents due to the increased porosity and chemical stability. This work underscores the opportunity in using steric hindrance to tune and control layer stacking, chemical stability and properties of 2D COFs.
- Wu, Xiaowei,Han, Xing,Liu, Yuhao,Liu, Yan,Cui, Yong
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supporting information
p. 16124 - 16133
(2018/11/23)
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- Highly active, separable and recyclable bipyridine iridium catalysts for C-H borylation reactions
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Iridium complexes generated from Ir(i) precursors and PIB oligomer functionalized bpy ligands efficiently catalyzed the reactions of arenes with bis(pinacolato)diboron under mild conditions to produce a variety of arylboronate compounds. The activity of this PIB bound homogeneous catalyst is similar to that of an original non-recyclable catalyst which allows it to be used under milder conditions than other reported recyclable catalysts. This oligomer-supported Ir catalyst was successfully recovered through biphasic extraction and reused for eight cycles without a loss of activity. Biphasic separation after the initial use of the catalyst led to an insignificant amount of iridium leaching from the catalyst to the product, and no iridium leaching from the catalyst was observed in the subsequent recycling runs. Arylboronate products obtained after extraction are sufficiently pure as observed by 1H and 13C-NMR spectroscopy that they do not require further purification.
- Mamlouk, Hind,Suriboot, Jakkrit,Manyam, Praveen Kumar,Alyazidi, Ahmed,Bergbreiter, David E.,Madrahimov, Sherzod T.
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p. 124 - 127
(2018/01/17)
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- Radical Metal-Free Borylation of Aryl Iodides
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A simple metal-free borylation of aryl iodides mediated by a fluoride sp 2 -sp 3 diboron adduct is described. The reaction conditions are compatible with various functional groups. Electronic effects of substituents do not affect the borylation while steric hindrance does. The reaction proceeds via a radical mechanism in which pyridine serves to stabilize the boryl radicals, generated in situ.
- Pinet, Sandra,Liautard, Virginie,Debiais, Mégane,Pucheault, Mathieu
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p. 4759 - 4768
(2017/10/03)
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- High-Turnover Aromatic C-H Borylation Catalyzed by POCOP-Type Pincer Complexes of Iridium
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The catalytic C-H borylation of arenes with HBpin (pin = pinacolate) using POCOP-type pincer complexes of Ir has been demonstrated, with turnover numbers exceeding 10 000 in some cases. The selectivity of C-H activation was based on steric preferences and largely mirrored that found in other Ir borylation catalysts. Catalysis in the (POCOP)Ir system depends on the presence of stoichiometric quantities of sacrificial olefin, which is hydrogenated to consume the H2 equivalents generated in the borylation of C-H bonds with HBpin. Smaller olefins such as ethylene or 1-hexene were more advantageous to catalysis than sterically encumbered tert-butylethylene (TBE). Olefin hydroboration is a competing side reaction. The synthesis and isolation of multiple complexes potentially relevant to catalysis permitted examination of several key elementary reactions. These experiments indicate that the C-H activation step in catalysis ostensibly involves oxidative addition of an aromatic C-H bond to the three-coordinate (POCOP)Ir species. The olefin is mechanistically critical to gain access to this 14-electron, monovalent Ir intermediate. C-H activation at Ir(I) here is in contrast to the olefin-free catalysis with state-of-the-art Ir complexes supported by neutral bidentate ligands, where the C-H activating step is understood to involve trivalent Ir-boryl intermediates.
- Press, Loren P.,Kosanovich, Alex J.,McCulloch, Billy J.,Ozerov, Oleg V.
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supporting information
p. 9487 - 9497
(2016/08/12)
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- Metal-Organic Frameworks Stabilize Mono(phosphine)-Metal Complexes for Broad-Scope Catalytic Reactions
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Mono(phosphine)-M (M-PR3; M = Rh and Ir) complexes selectively prepared by postsynthetic metalation of a porous triarylphosphine-based metal-organic framework (MOF) exhibited excellent activity in the hydrosilylation of ketones and alkenes, the hydrogenation of alkenes, and the C-H borylation of arenes. The recyclable and reusable MOF catalysts significantly outperformed their homogeneous counterparts, presumably via stabilizing M-PR3 intermediates by preventing deleterious disproportionation reactions/ligand exchanges in the catalytic cycles.
- Sawano, Takahiro,Lin, Zekai,Boures, Dean,An, Bing,Wang, Cheng,Lin, Wenbin
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supporting information
p. 9783 - 9786
(2016/08/19)
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- Iridium-bipyridine periodic mesoporous organosilica catalyzed direct C-H borylation using a pinacolborane
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Heterogeneous catalysis for direct C-H borylation of arenes and heteroarenes in the combination of iridium (Ir) complex fixed on periodic mesoporous organosilica containing bipyridine ligands within the framework (Ir-BPy-PMO) and pinacolborane (HBpin) is reported. Ir-BPy-PMO showed higher catalytic activity toward the borylation of benzene with inexpensive HBpin compared to expensive bis(pinacolato)diboron (B2pin2). The precatalyst could be handled without the use of a glove box. The catalyst was easily recovered from reaction mixtures by simple filtration under air. The recovered catalyst still showed good catalytic activity for at least three more times for the borylation of benzene. A variety of arenes and heteroarenes were successfully borylated with high boron efficiency by Ir-BPy-PMO using HBpin, whereas almost no activity was observed for borylation of some heteroarenes with B2pin2. The system using Ir-BPy-PMO and HBpin was also utilized in syntheses of multi-boronated thiophene-based building blocks containing ladder-, acenefused-, and fused-thiophene skeletons. The combination of a stable and reusable solid catalyst and inexpensive HBpin is expected to be superior to conventional approaches for the development of industrial applications.
- Maegawa, Yoshifumi,Inagaki, Shinji
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supporting information
p. 13007 - 13016
(2016/01/09)
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- Harnessing C-H Borylation/Deborylation for Selective Deuteration, Synthesis of Boronate Esters, and Late Stage Functionalization
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Ir-catalyzed deborylation can be used to selectively deuterate aromatic and heteroaromatic substrates. Combined with the selectivities of Ir-catalyzed C-H borylations, uniquely labeled compounds can be prepared. In addition, diborylation/deborylation reactions provide monoborylated regioisomers that complement those prepared by C-H borylation. Comparisons between Ir-catalyzed deborylations and Pd-catalyzed deborylations of diborylated indoles described by Movassaghi are made. The Ir-catalyzed process is more effective for deborylating aromatics and is generally more effective in the monodeborylation of diborylated thiophenes. These processes can be applied to complex molecules such as clopidogrel.
- Kallepalli, Venkata A,Gore, Kristin A.,Shi, Feng,Sanchez, Luis,Chotana, Ghayoor A.,Miller, Susanne L.,Maleczka, Robert E.,Smith, Milton R.
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p. 8341 - 8353
(2015/09/02)
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- Bipyridine- and phenanthroline-based metal-organic frameworks for highly efficient and tandem catalytic organic transformations via directed C-H activation
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We report here the synthesis of a series of robust and porous bipyridyl- and phenanthryl-based metal-organic frameworks (MOFs) of UiO topology (BPV-MOF, mBPV-MOF, and mPT-MOF) and their postsynthetic metalation to afford highly active single-site solid catalysts. While BPV-MOF was constructed from only bipyridyl-functionalized dicarboxylate linker, both mBPV- and mPT-MOF were built with a mixture of bipyridyl- or phenanthryl-functionalized and unfunctionalized dicarboxylate linkers. The postsynthetic metalation of these MOFs with [Ir(COD)(OMe)]2 provided Ir-functionalized MOFs (BPV-MOF-Ir, mBPV-MOF-Ir, and mPT-MOF-Ir), which are highly active catalysts for tandem hydrosilylation of aryl ketones and aldehydes followed by dehydrogenative ortho-silylation of benzylicsilyl ethers as well as C-H borylation of arenes using B2pin2. Both mBPV-MOF-Ir and mPT-MOF-Ir catalysts displayed superior activities compared to BPV-MOF-Ir due to the presence of larger open channels in the mixed-linker MOFs. Impressively, mBPV-MOF-Ir exhibited high TONs of up to 17000 for C-H borylation reactions and was recycled more than 15 times. The mPT-MOF-Ir system is also active in catalyzing tandem dehydrosilylation/dehydrogenative cyclization of N-methylbenzyl amines to azasilolanes in the absence of a hydrogen acceptor. Importantly, MOF-Ir catalysts are significantly more active (up to 95 times) and stable than their homogeneous counterparts for all three reactions, strongly supporting the beneficial effects of active site isolation within MOFs. This work illustrates the ability to increase MOF open channel sizes by using the mixed linker approach and shows the enormous potential of developing highly active and robust single-site solid catalysts based on MOFs containing nitrogen-donor ligands for important organic transformations.
- Manna, Kuntal,Zhang, Teng,Greene, Francis X.,Lin, Wenbin
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supporting information
p. 2665 - 2673
(2015/03/04)
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- Para -C-H borylation of benzene derivatives by a bulky iridium catalyst
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A highly para-selective aromatic C-H borylation has been accomplished. By a new iridium catalyst bearing a bulky diphosphine ligand, Xyl-MeO-BIPHEP, the C-H borylation of monosubstituted benzenes can be affected with para-selectivity up to 91%. This catalytic system is quite different from the usual iridium catalysts that cannot distinguish meta- and para-C-H bonds of monosubstituted benzene derivatives, resulting in the preferred formation of meta-products. The para-selectivity increases with increasing bulkiness of the substituent on the arene, indicating that the regioselectivity of the present reaction is primarily controlled by steric repulsion between substrate and catalyst. Caramiphen, an anticholinergic drug used in the treatment of Parkinsons disease, was converted into five derivatives via our para-selective borylation. The present [Ir(cod)OH]2/Xyl-MeO-BIPHEP catalyst represents a unique, sterically controlled, para-selective, aromatic C-H borylation system that should find use in streamlined, predictable chemical synthesis and in the rapid discovery and optimization of pharmaceuticals and materials.
- Saito, Yutaro,Segawa, Yasutomo,Itami, Kenichiro
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supporting information
p. 5193 - 5198
(2015/05/05)
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- Fluorine-controlled C-H borylation of arenes catalyzed by a PSiN-pincer platinum complex
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An efficient, regioselective synthesis of fluorine-substituted arylboronic esters was achieved through fluorine-controlled C-H borylation of arenes with diboron catalyzed by a PSiN-platinum complex. The promising utility of the PSiN-platinum catalyst and its unique regioselectivity were demonstrated for the first time, which would complement the well-developed Ir-catalyzed C-H borylation.
- Takaya, Jun,Ito, Shisei,Nomoto, Hironori,Saito, Narumasa,Kirai, Naohiro,Iwasawa, Nobuharu
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supporting information
p. 17662 - 17665
(2015/12/18)
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- Preparation and reactions of 4-iodobutyl pinacolborate. Synthesis of substituted alkyl and aryl pinacolboronates via 4-iodobutyl pinacolborate utilizing tetrahydrofuran as the leaving group
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Iodine reacts with 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (HBpin), under ambient reaction conditions in THF, to form the iodoalkylborate species 2-(4-iodobutoxy)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (4-IboxBpin). Apparently, one-half equivalent of I2 reacts with HBpin to form IBpin in pentanes, which in turn cleaves THF to form the 4-IboxBpin. Alkyl and aryl Grignard reagents, prepared under Barbier conditions, then react with 4-IboxBpin to form the corresponding alkyl and aryl pinacolboronates while reforming and liberating THF as the leaving group.
- Murphy, Chris L.,Hall, Aaron,Roberts, Emily J.,Ryan, Matthew D.,Clary, Jacob W.,Singaram, Bakthan
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p. 3032 - 3033
(2015/02/19)
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- Regioselective electrophilic borylation of haloarenes
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Haloarenes undergo direct borylation using amine:BCl3:AlCl3 in the ratio of 1:1:2. After esterification the pinacol boronate esters are isolated in good yield with regioselectivity controlled by steric and electronic effects.
- Del Grosso, Alessandro,Ayuso Carrillo, Josue,Ingleson, Michael J.
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supporting information
p. 2878 - 2881
(2015/02/19)
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- New process for preparing arylboranes by arylation of organoboron compounds
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The present invention relates to a new process for the preparation of an arylborane compound, by arylation of a B-H bond, which comprises a step (1) of contacting an arenediazonium salt or a heteroarenediazonium salt with an organoboron compound containing at least one B-H bond, in a reaction medium containing a solvent, in the absence of base, in the absence or in the presence of an activating agent, for the preparation of an arylborane compound, and a possible step (2) of recovery and purification of said arylborane compound obtained at the step (1), said arylborane being in particular an aminoarylborane, and a possible step (3) of refunctionalisation of said arylborane obtained at step (1) or (2) for the preparation of aryl boronic derivatives or arylborates.
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Paragraph 0108; 0109; 0110; 0111; 0151; 0152; 0153
(2014/01/23)
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- Borylation using group IV metallocene under mild conditions
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A borylation reaction of aromatic diazonium salts has been optimized using titanocene and zirconocene derivatives as catalysts. The reaction employs diisopropylaminoborane as a borylating agent and proceeds smoothly at room temperature to provide arylboronates after methanolysis and transesterification with pinacol. The reaction mechanism has been found to proceed via a radical pathway.
- Marciasini, Ludovic D.,Vaultier, Michel,Pucheault, Mathieu
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p. 1702 - 1705
(2014/03/21)
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- Postsynthetic metalation of bipyridyl-containing metal-organic frameworks for highly efficient catalytic organic transformations
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We have designed highly stable and recyclable single-site solid catalysts via postsynthetic metalation of the 2,2-bipyridyl-derived metal-organic framework (MOF) of the UiO structure (bpy-UiO). The Ir-functionalized MOF (bpy-UiO-Ir) is a highly active catalyst for both borylation of aromatic C-H bonds using B2(pin)2 (pin = pinacolate) and ortho-silylation of benzylicsilyl ethers; the ortho-silylation activity of the bpy-UiO-Ir is at least 3 orders of magnitude higher than that of the homogeneous control. The Pd-functionalized MOF (bpy-UiO-Pd) catalyzes the dehydrogenation of substituted cyclohexenones to afford phenol derivatives with oxygen as the oxidant. Most impressively, the bpy-UiO-Ir was recycled and reused 20 times for the borylation reaction without loss of catalytic activity or MOF crystallinity. This work highlights the opportunity in designing highly stable and active catalysts based on MOFs containing nitrogen donor ligands for important organic transformations.
- Manna, Kuntal,Zhang, Teng,Lin, Wenbin
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supporting information
p. 6566 - 6569
(2014/05/20)
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- A solid chelating ligand: Periodic mesoporous organosilica containing 2,2′-bipyridine within the pore walls
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Synthesis of a solid chelating ligand for the formation of efficient heterogeneous catalysts is highly desired in the fields of organic transformation and solar energy conversion. Here, we report the surfactant-directed self-assembly of a novel periodic mesoporous organosilica (PMO) containing 2,2′-bipyridine (bpy) ligands within the framework (BPy-PMO) from a newly synthesized organosilane precursor [(i-PrO) 3Si-C10H6N2-Si(Oi-Pr)3] without addition of any other silane precursors. BPy-PMO had a unique pore-wall structure in which bipyridine groups were densely and regularly packed and exposed on the surface. The high coordination ability to metals was also preserved. Various bipyridine-based metal complexes were prepared using BPy-PMO as a solid chelating ligand such as Ru(bpy)2(BPy-PMO), Ir(ppy) 2(BPy-PMO) (ppy = 2-phenylpyridine), Ir(cod)(OMe)(BPy-PMO) (cod = 1,5-cyclooctadiene), Re(CO)3Cl(BPy-PMO), and Pd(OAc) 2(BPy-PMO). BPy-PMO showed excellent ligand properties for heterogeneous Ir-catalyzed direct C-H borylation of arenes, resulting in superior activity, durability, and recyclability to the homogeneous analogous Ir catalyst. An efficient photocatalytic hydrogen evolution system was also constructed by integration of a Ru-complex as a photosensitizer and platinum as a catalyst on the pore surface of BPy-PMO without any electron relay molecules. These results demonstrate the great potential of BPy-PMO as a solid chelating ligand and a useful integration platform for construction of efficient molecular-based heterogeneous catalysis systems.
- Waki, Minoru,Maegawa, Yoshifumi,Hara, Kenji,Goto, Yasutomo,Shirai, Soichi,Yamada, Yuri,Mizoshita, Norihiro,Tani, Takao,Chun, Wang-Jae,Muratsugu, Satoshi,Tada, Mizuki,Fukuoka, Atsushi,Inagaki, Shinji
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supporting information
p. 4003 - 4011
(2014/04/03)
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- Regioselective conversion of arenes to N-aryl-1,2,3-triazoles Using C-H Borylation
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A one-pot protocol for the synthesis of N-aryl 1,2,3-triazoles from arenes by an iridium-catalyzed C-H borylation/copper catalyzed azidation/click sequence is described. 1mol % of Cu(OTf)2 was found to efficiently catalyze both the azidation and the click reaction. The applicability of this method is demonstrated by the late-stage chemoselective installation of 1,2,3-triazole moiety into unactivated molecules of pharmaceutical importance.
- Srinivasan, Rajavel,Coyne, Anthony G.,Abell, Chris
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supporting information
p. 11680 - 11684
(2014/10/15)
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- NEW PROCESS FOR PREPARING ARYLBORANES BY ARYLATION OF ORGANOBORON COMPOUNDS
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The present invention relates to a new process for the preparation of an arylborane compound, by arylation of a B-H bond, which comprises a step (1) of contacting an arenediazonium salt or a heteroarenediazonium salt with an organoboron compound containing at least one B-H bond, in a reaction medium containing a solvent, in the absence of base, in the absence or in the presence of an activating agent, for the preparation of an arylborane compound, and a possible step (2) of recovery and purification of said arylborane compound obtained at the step (1), said arylborane being in particular an aminoarylborane, and a possible step (3) of refunctionalisation of said arylborane obtained at step (1) or (2) for the preparation of aryl boronic derivatives or arylborates.
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Page/Page column 53-54; 67-68
(2014/02/15)
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- Iron-catalysed borylation of arenediazonium salts to give access to arylboron derivatives via aryl(amino)boranes at room temperature
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Complementary to previously described Miyaura borylation methods, a new access to boron derivatives via aryl(amino)boranes is described. Direct coupling between aryldiazonium salts and diisopropylaminoborane is catalysed by 0.1% ferrocene leading to the formation of a carbon-boron bond. The obtained aryl(amino)boranes could eventually then be transformed into boronic acids, boronates or borates. Copyright
- Marciasini, Ludovic D.,Richy, Nicolas,Vaultier, Michel,Pucheault, Mathieu
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p. 1083 - 1088
(2013/05/21)
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- Synthesis of pinacol arylboronates from aromatic amines: A metal-free transformation
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A metal-free borylation process based on Sandmeyer-type transformation using arylamines derivatives as the substrates has been developed. Through optimization of the reaction conditions, this novel conversion can be successfully applied to a wide range of aromatic amines, affording borylation products in moderate to good yields. Various functionalized arylboronates, which are difficult to access by other methods, can be easily obtained with this metal-free transformation. Moreover, this transformation can be followed by Suzuki-Miyaura cross-coupling without purification of the borylation products, which enhances the practical usefulness of this method. A possible reaction mechanism involving radical species has been proposed.
- Qiu, Di,Jin, Liang,Zheng, Zhitong,Meng, He,Mo, Fanyang,Wang, Xi,Zhang, Yan,Wang, Jianbo
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p. 1923 - 1933
(2013/03/29)
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- Sterically controlled iodination of arenes via iridium-catalyzed C-H borylation
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A mild method to prepare aryl and heteroaryl iodides by sequential C-H borylation and iodination is reported. The regioselectivity of this process is controlled by steric effects on the C-H borylation step and is complementary to existing methods to form aryl iodides. The iodination of boronic esters has potential for the synthesis of radiolabeled aryl iodides, as demonstrated by the concise synthesis of a potential tracer for SPECT imaging.
- Partridge, Benjamin M.,Hartwig, John F.
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supporting information
p. 140 - 143
(2013/03/28)
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- PREPARATION METHOD OF AROMATIC BORONATE COMPOUNDS
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Preparation method of aromatic boronate compound is provided, in which the is as follows: reacting aromatic amine Ar-NH2, with diboronic ester and alkyl nitrite in the presence of organic solvent, where Ar represents non-heterocyclic aryl. It enables for the first time the preparation of aromatic boronate from aromatic amine in one step by the present method.
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Page/Page column 3
(2012/07/28)
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- PREPARATION METHOD OF AROMATIC BORATE ESTER COMPOUND
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Preparation method of aromatic boronate compound is provided, in which the step is as follows: reacting aromatic amine Ar-NH2, with diboronic ester and alkyl nitrite in the presence of organic solvent, where Ar represents non-heterocyclic aryl.
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Page/Page column 5
(2012/08/08)
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- Enantioselective syntheses of (+)-sertraline and (+)-indatraline using lithiation/borylation-protodeboronation methodology
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The lithiation/borylation-protodeboronation of a homoallyl carbamate was applied to the synthesis of (+)-sertraline and (+)-indatraline. Due to the presence of the alkene, significant modifications of the methodology were required (use of 12-crown-4, TMSCl, H2O), or a solvent switch to CHCl3, to achieve high yields and high selectivities.
- Roesner, Stefan,Casatejada, Javier Mansilla,Elford, Tim G.,Sonawane, Ravindra P.,Aggarwal, Varinder K.
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supporting information; experimental part
p. 5740 - 5743
(2011/12/22)
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- Direct conversion of arylamines to pinacol boronates: A metal-free borylation process
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Leave the metal out: Arylboronates are produced In moderate to good yields by direct borylation of readily available aryl amines (see scheme). The reaction can be carried out under air at room temperature and transition-metal catalysis is not required. The boronate products can be used without purification in SuzukiMiyaura cross-coupling reactions. Chemical equation representation
- Mo, Fanyang,Jiang, Yubo,Qiu, Di,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 1846 - 1849
(2010/06/16)
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- Continuous-Flow C-H borylation of arene derivatives
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A new continuous-flow system for C-H borylation has been developed. An insoluble catalyst prepared from chloro(1,5-cyclooctadien)iridium(I) dimer and 2,2′-bipyridine-4,4′-dicarboxylic acid in the presence of bis(pinacolato)diboron exhibited high reactivity under continuous-flow processing without the loss of expensive iridium metal.
- Tagata, Tsuyoshi,Nishida, Mayumi,Nishida, Atsushi
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experimental part
p. 1662 - 1666
(2010/09/15)
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- Iridium complexes of N-heterocyclic carbenes in C-H borylation using energy efficient microwave technology: Influence of structure, ligand donor strength and counter ion on catalytic activity
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Bridged and unbridged N-heterocyclic carbene (NHC) ligands were metalated with [Ir(COD)Cl]2 to give iridium(i) mono- and biscarbene substituted catalysts [Ir(COD)NHC(Cl)] and [Ir(COD)(NHC)2][X] (X: I, PF 6, BF4, CF3COO, OTf). The prepared NHC-complexes were tested in the C-H borylation reaction of aromatic carbons with bis(pinacolato)diboron (B2pin2) and pinacolborane (HBpin). The use of microwave technology in this study not only facilitates a time efficient screening of a wide range of influences such as ligand σ-donor strength and structural motif as well as the effects of the complex counter ion, but also provides an energy efficient heating source. Catalyst 6TFA, which features a chelating NHC ligand, proved to be most effective catalyst and further investigations with this complex in the borylation of mono- and disubstituted benzene derivatives exploring chemo- and regioselectivity were undertaken. The Royal Society of Chemistry 2009.
- Rentzsch, Christoph F.,Tosh, Evangeline,Herrmann, Wolfgang A.,Kuehn, Fritz E.
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scheme or table
p. 1610 - 1617
(2010/05/18)
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- Development of recyclable iridium catalyst for C-H borylation
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Aromatic C-H borylation using [IrCl(COD)]2 and 2,2′-bipyridinedicarboxylic acids was studied. 2,2′-Bipyridine-4,4′-dicarboxylic acid was complexed with [IrCl(COD)]2 in the presence of bis(pinacolato)diboron. The resulting iridium catalyst could be readily separated from the reaction mixture by simple filtration, and the recovered catalyst under a nitrogen atmosphere was still active and could be reused more than 10 times.
- Tagata, Tsuyoshi,Nishida, Mayumi,Nishida, Atsushi
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scheme or table
p. 6176 - 6179
(2009/12/26)
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- Iridium-catalyzed preparation of silylboranes by silane borylation and their use in the catalytic borylation of arenes
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Silylboranes are versatile reagents for transition metal-catalyzed reactions of unsaturated organic molecules. These reagents are typically prepared by the addition of a silyl lithium species to a boron electrophile. However, the need to generate anionic silane reagents limits the scope of silylboranes that can be readily obtained. Here, we describe the synthesis of trialkylsilylboranes by the borylation of silanes catalyzed by iridium complexes. The reaction of trialkylhydrosilanes with B2pin 2 catalyzed by the combination of [Ir(OMe)cod]2 and 4,4′-di-tert-butylbipyridine forms trialkylsilylboronic esters. In addition, we show that these trialkylsilylboranes serve as boron sources for the iridium-catalyzed borylation of aryl C-H bonds. In contrast to diboron reagents, the silylboranes react with methylarenes at both the aryl and methyl C-H bonds.
- Boebel, Timothy A.,Hartwig, John F.
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p. 6013 - 6019
(2009/04/13)
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- Practical synthesis of pinacolborane for one-pot synthesis of unsymmetrical biaryls via aromatic C-H borylation-cross-coupling sequence
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A method for practical preparation of pinacolborane from borane-diethylaniline and pinacol was newly developed. Aromatic C-H borylation of arenes with pinacolborane or bis(pinacolato)diboron catalyzed by 1/2[Ir(OMe)(COD)]2-(4,4′-di-tert-butyl-2,2′-bipyridine) at 25 °C in hexane to give arylboronic esters was directly followed by cross-coupling with aromatic bromides at 60 °C in the presence of PdCl2(dppf) (3.0 mol %) and K3PO4 in DMF. This one-pot, two-step procedure provided a variety of unsymmetrical biaryls in high yields.
- Kikuchi, Takao,Nobuta, Yusuke,Umeda, Junko,Yamamoto, Yasunori,Ishiyama, Tatsuo,Miyaura, Norio
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p. 4967 - 4971
(2008/09/21)
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- Mechanism of the mild functionalization of arenes by diboron reagents catalyzed by iridium complexes. Intermediacy and chemistry of bipyridine-ligated iridium trisboryl complexes
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This paper describes mechanistic studies on the functionalization of arenes with the diboron reagent B2pin2 (bis-pinacolato diborane(4)) catalyzed by the combination of 4,4′-di-tert-butylbipyridine (dtbpy) and olefin-ligated iridium halide or olefin-ligated iridium alkoxide complexes. This work identifies the catalyst resting state as [Ir(dtbpy)(COE)(Bpin)3] (COE = cyclooctene, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaborolanyl). [Ir(dtbpy)(COE)(Bpin)3] was prepared by independent synthesis in high yield from [Ir(COD)(OMe)] 2, dtbpy, COE, and HBpin. This complex is formed in low yield from [Ir(COD)(OMe)]2, dtbpy, COE, and B2pin2. Kinetic studies show that this complex reacts with arenes after reversible dissociation of COE. An alternative mechanism in which the arene reacts with the Ir(I) complex [Ir(dtbpy)Bpin] after dissociation of COE and reductive elimination of B2pin2 does not occur to a measurable extent. The reaction of [Ir(dtbpy)(COE)(Bpin)3] with arenes and the catalytic reaction of B2pin2 with arenes catalyzed by [Ir(COD)(OMe)]2 and dtbpy occur faster with electron-poor arenes than with electron-rich arenes. However, both the stoichiometric and catalytic reactions also occur faster with the electron-rich heteroarenes thiophene and furan than with arenes, perhaps because η2-heteroarene complexes are more stable than the η2-arene complexes and the η2-heteroarene or arene complexes are intermediates that precede oxidative addition. Kinetic studies on the catalytic reaction show that [Ir(dtbpy)(COE)(Bpin)3] enters the catalytic cycle by dissociation of COE, and a comparison of the kinetic isotope effects of the catalytic and stoichiometric reactions shows that the reactive intermediate [Ir(dtbpy)(Bpin)3] cleaves the arene C-H bond. The barriers for ligand exchange and C-H activation allow an experimental assessment of several conclusions drawn from computational work. Most generally, our results corroborate the conclusion that C-H bond cleavage is turnover-limiting, but the experimental barrier for this bond cleavage is much lower than the calculated barrier.
- Boller, Timothy M.,Murphy, Jaclyn M.,Hapke, Marko,Ishiyama, Tatsuo,Miyaura, Norio,Hartwig, John F.
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p. 14263 - 14278
(2007/10/03)
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- Mild iridium-catalyzed borylation of arenes. High turnover numbers, room temperature reactions, and isolation of a potential intermediate
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The borylation of arenes leads to the formation of synthetically versatile products from unactivated arene reagents. We report that Ir(I) precursors in conjunction with bipyridine ligands catalyze in high yields the borylation of arenes under mild conditions. These reactions encompase arenes bearing both electron-withdrawing and electron-donating substituents. The temperatures required for the transformation are much lower than those previously reported for direct arene borylation. The combination of [Ir(COE)2Cl]2 and (4,4-di-t-butyl)bipyridine even allows for reaction at room temperature. The same catalyst system at 100 °C provides remarkably high turnover numbers for a hydrocarbon functionalization process. Mechanistic studies show that the reactions involve uncommon, Ir(II) tris-boryl complexes. An example of this type of complex ligated by di-t-butylbipyridine was isolated and structurally characterized. It reacted rapidly at room temperature to produce aryl boronate esters in high yields. Copyright
- Ishiyama, Tatsuo,Takagi, Jun,Ishida, Kousaku,Miyaura, Norio,Anastasi, Natia R.,Hartwig, John F.
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p. 390 - 391
(2007/10/03)
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- A stoichiometric aromatic C-H borylation catalyzed by iridium(I)/2,2′-bipyridine complexes at room temperature
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Room-temperature C-H borylation using a stoichiometric amount of arenes and bis(pinacolato)diboron (pin2B2) is efficiently catalyzed by iridium(I) complexes generated from [{Ir(OMe)(cod)}2] (cod=1,5-cyclooctadiene) and 4,4′-di-tertbutyl-2,2′-bipyridine (dtbpy) in hexane, and provides the corresponding arylboronates in excellent yields [Eq. (1)].
- Ishiyama, Tatsuo,Takagi, Jun,Hartwig, John F.,Miyaura, Norio
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p. 3056 - 3058
(2007/10/03)
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