- Direct C?H Borylation of Arenes Catalyzed by Saturated Hydride-Boryl-Iridium-POP Complexes: Kinetic Analysis of the Elemental Steps
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The saturated trihydride IrH3{κ3-P,O,P-[xant(PiPr2)2]} (1; xant(PiPr2)2=9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) activates the B?H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride-boryl derivatives IrH2(Bpin){κ3-P,O,P-[xant(PiPr2)2]} (2) and IrH(Bpin)2{κ3-P,O,P-[xant(PiPr2)2]} (3) in a sequential manner. Complex 3 activates a C?H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1, also in a sequential manner. Thus, complexes 1, 2, and 3 define two cycles for the catalytic direct C?H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C?H bond activation of the arenes is the rate-determining step of both cycles, as the C?H oxidative addition to 3 is faster than to 2. The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B?H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B?H bond through the formation of κ1- and κ2-dihydrideborate intermediates.
- Esteruelas, Miguel A.,Martínez, Antonio,Oliván, Montserrat,O?ate, Enrique
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supporting information
p. 12632 - 12644
(2020/09/09)
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- Highly Selective and Divergent Acyl and Aryl Cross-Couplings of Amides via Ir-Catalyzed C-H Borylation/N-C(O) Activation
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Herein, we demonstrate that amides can be readily coupled with nonactivated arenes via sequential Ir-catalyzed C-H borylation/N-C(O) activation. This methodology provides facile access to biaryl ketones and biaryls by the sterically controlled Ir-catalyzed C-H borylation and divergent acyl and decarbonylative amide N-C(O) and C-C activation. The methodology diverts the traditional acylation and arylation regioselectivity, allowing us to directly utilize readily available arenes and amides to produce valuable ketone and biaryl motifs.
- Gao, Pengcheng,Szostak, Michal
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supporting information
p. 6010 - 6015
(2020/07/30)
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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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- Palladium-Catalyzed Methylation of Aryl, Heteroaryl, and Vinyl Boronate Esters
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A method for the direct methylation of aryl, heteroaryl, and vinyl boronate esters is reported, involving the reaction of iodomethane with aryl-, heteroaryl-, and vinylboronate esters catalyzed by palladium and PtBu2Me. This transformation occurs with a remarkably broad scope and is suitable for late-stage derivatization of biologically active compounds via the boronate esters. The unique capabilities of this method are demonstrated by combining carbon-boron bond-forming reactions with palladium-catalyzed methylation in a tandem transformation.
- Haydl, Alexander M.,Hartwig, John F.
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supporting information
p. 1337 - 1341
(2019/02/26)
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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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- 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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- PYRAZOLO PYRIMIDINE DERIVATIVES AND METHODS OF USE THEREOF
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This invention generally relates to pyrazolo pyrimidine derivatives useful as, inter alia, inhibitors of short chain dehydrogenase/reductase (SDR) family of NAD(P)(H) dependent oxido-reductases. More specifically, the invention relates to pyrazolo pyrimid
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Paragraph 0241
(2016/07/05)
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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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p. 1365 - 1375
(2014/05/20)
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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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- Sterically controlled alkylation of arenes through iridium-catalyzed C-H borylation
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Complementary chemistry: A one-pot method for the site-selective alkylation of arenes controlled by steric effects is reported. The process occurs through Ir-catalyzed C-H borylation, followed by Pd- or Ni-catalyzed coupling with alkyl electrophiles. This selectivity complements that of the typical Friedel-Crafts alkylation; meta-selective alkylation of a broad range of arenes with various electronic properties and functional groups occurs in good yield with high site selectivity. Copyright
- Robbins, Daniel W.,Hartwig, John F.
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supporting information
p. 933 - 937
(2013/02/25)
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- Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate
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Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 4402 - 4413
(2012/06/18)
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- Conversion of 1,3-disubstituted arenes to chiral α,α-diaryl methylammonium chlorides using arene borylation
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A two-step conversion of 1,3-disubstituted arenes to chiral α,α-diaryl methylammonium chlorides is described. In this procedure, arenes are converted to aryl boronic esters by iridium-catalyzed borylation, and the aryl boronic esters are converted to enantioenriched amines by subsequent rhodium-catalyzed addition to chiral tert-butanesulfinimes.
- Boebel, Timothy A.,Hartwig, John F.
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p. 6824 - 6830
(2008/09/21)
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- One-pot synthesis of arylboronic acids and aryl trifluoroborates by Ir-catalyzed borylation of arenes
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(Chemical Equation Presented) The synthesis of arylboronic acids and aryl trifluoroborates in a one-pot sequence by Ir-calalyzed borylation of arenes is reported. To prepare the arylboronic acids, the Ir-catalyzed borylation is followed by oxidative cleavage of the boronic ester with NaIO4. To prepare the aryltrifluoroborate, the Ir-catalyzed borylation is followed by displacement of pinacol by KHF2. These two-step sequences give products that are more reactive toward subsequent chemistry than the initially formed pinacol boronates.
- Murphy, Jaclyn M.,Tzschucke, C. Christoph,Hartwig, John F.
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p. 757 - 760
(2007/10/03)
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- Arenes to anilines and aryl ethers by sequential iridium-catalyzed borylation and copper-catalyzed coupling
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(Chemical Equation Presented) N-Alkyl- and N-arylanilines were synthesized from arenes by a two-step sequence of iridium-catalyzed borylation and copper-catalyzed coupling with amines. Diaryl ethers were obtained by a related sequence of arene borylation, followed by coupling with phenols. In particular, 3,5-disubstituted arylamines and aryl ethers were prepared by initiating this sequence with meta-substituted arenes.
- Tzschucke, C. Christoph,Murphy, Jaclyn M.,Hartwig, John F.
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p. 761 - 764
(2007/10/03)
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- Meta halogenation of 1,3-disubstituted arenes via iridium-catalyzed arene borylation
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We report the meta halogenation of 1,3-disubstituted arenes to form 3,5-disubstituted aryl bromides and chlorides by using iridium-catalyzed arene borylation chemistry. Iridium-catalyzed borylation of arenes with B2pin2, followed by reaction of the boronic ester with copper(II) bromide or chloride converts arylboronic esters to the corresponding aryl halides. A variety of arenes containing alkoxy, alkyl, halogen, nitrile, ester, amide, and pivaloyl and TIPS-protected alcohols were converted to the corresponding 3,5-disubstituted aryl bromides and chlorides in yields ranging from 46% to 85%. In addition, 2,6-disubstituted and 3-substituted pyridines were converted to the 4-halo and 5-halopyridines, respectively. The utility of this methodology was demonstrated by the formal conversion of nicotine to Altinicline in three steps with an overall yield of 61% using meta bromination of nicotine as the first step. Copyright
- Murphy, Jaclyn M.,Liao, Xuebin,Hartwig, John F.
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p. 15434 - 15435
(2008/09/19)
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- Substituted imidazol-pyridazine derivatives
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The present invention relates to compounds of formula wherein A is an unsubstituted or substituted cyclic group; and R is hydrogen or lower alkyl; or a pharmaceutically acceptable acid addition salt thereof. These compounds are NMDA NR-2B receptor subtype specific blockers and are useful in the treatment of neurodegeneration, depression and pain.
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- 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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p. 2924 - 2925
(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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