- Direct Installation of a Silyl Linker on Ready-Made NHC Ligands: Immobilized NHC-Pd Complex for Buchwald-Hartwig Amination
-
An immobilized N-heterocyclic carbene (NHC)-Pd complex was prepared via direct silyl linker installation onto the imidazole backbone of commercially available 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) ligand. The IPr backbone was lithiated and treated with Me2SiCl2 to afford ClMe2Si-IPr, which reacted with [Pd(π-allyl)Cl]2 to yield a ClMe2Si-IPr-Pd complex, and this was immobilized on Wang resin. The immobilized NHC-Pd complex facilitated quantitative Buchwald-Hartwig amination of aryl chlorides within 10 min, even at a low Pd loading of 0.2 mol %. The catalyst could be removed from the reaction mixture by simple filtration, and Pd leaching into the reaction medium was suppressed to below 1 ppm.
- Mizusaki, Tomoteru,Matsumoto, Kazuhiro,Takeuchi, Katsuhiko,Fukaya, Norihisa,Takagi, Yukio,Choi, Jun-Chul
-
-
Read Online
- A Selective C?H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine
-
Described here is an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts. The iodonium salts are prepared in a single pot from either commercially available aryl iodides or arylboronic acids. The
- Sundalam, Sunil K.,Nilova, Aleksandra,Seidl, Thomas L.,Stuart, David R.
-
-
Read Online
- Mixed Phosphite-Phosphine and Phosphinite-Phosphine Palladacyclic Complexes as Highly Active Catalysts for the Amination of Aryl Chlorides
-
Tri-tert-butylphosphine adducts of orthopalladated phosphite and phosphinite complexes formed in situ are excellent catalysts for the Buchwald-Hartwig amination of aryl chloride substrates.
- Bedford, Robin B.,Blake, Michael E.
-
-
Read Online
- Palladium(II) Complexes with Anionic N-Heterocyclic Carbene-Borate Ligands as Catalysts for the Amination of Aryl Halides
-
A series of (allyl)palladium(II) complexes of anionic N-heterocyclic carbenes that contain a weakly coordinating borate moiety (WCA-NHC) were prepared by deprotonation of the carbene IPr with n-butyllithium in the 4-position, which was followed by addition of B(C6F5)3 and reaction of the resulting lithium carbene-borate with [(η3-allyl)Pd(μ-Cl)]2 (allyl = 2-propenyl, 2-butenyl, 2-methyl-2-propenyl, 1-phenyl-2-propenyl). In polar solvents such as tetrahydrofuran, chloropalladate complexes of the type [Li(THF)3][(WCA-NHC)PdCl(η3-allyl)] were formed, whereas the reactions in toluene afforded neutral complexes of the type [(WCA-NHC)Pd(η3-allyl)], which exhibit an intramolecular interaction with the N-aryl groups of the carbene ligands. The allyl-palladium complexes were employed as catalysts for the Buchwald-Hartwig amination of various aryl halides with morpholine.
- Winkler, Andrea,Brandhorst, Kai,Freytag, Matthias,Jones, Peter G.,Tamm, Matthias
-
-
Read Online
- Carbocyclic carbene ligands in palladium-catalyzed C-N coupling reactions
-
Palladium complexes bearing a cycloheptatrienylidene ligand are powerful precatalysts for C-N coupling reactions. Their catalytic performance is directly compared to analogous 2,3-diphenylcyclopropenylidene complexes. The crystal structure of cis-dibromo(
- Taubmann, Christian,Tosh, Evangeline,?fele, Karl,Herdtweck, Eberhardt,Herrmann, Wolfgang A.
-
-
Read Online
- Enhanced activity of [Ni(NHC)CpCl] complexes in arylamination catalysis
-
Seven new air- and moisture-stable nickel complexes bearing flexible bulky NHC (N-heterocyclic carbene) ancillary ligands (NHC = IPr, IPrTol, IPrOMe, IPent) are reported. Using experimentally determined crystal structures, the steric
- Martin, Anthony R.,Makida, Yusuke,Meiries, Sebastien,Slawin, Alexandra M. Z.,Nolan, Steven P.
-
-
Read Online
- Energy-Efficient Solar Photochemistry with Luminescent Solar Concentrator Based Photomicroreactors
-
The sun is the most sustainable light source available on our planet, therefore the direct use of sunlight for photochemistry is extremely appealing. Demonstrated here, for the first time, is that a diverse set of photon-driven transformations can be efficiently powered by solar irradiation with the use of solvent-resistant and cheap luminescent solar concentrator based photomicroreactors. Blue, green, and red reactors can accommodate both homogeneous and multiphase reaction conditions, including photochemical oxidations, photocatalytic trifluoromethylation chemistry, and metallaphotoredox transformations, thus spanning applications over the entire visible-light spectrum. To further illustrate the efficacy of these novel solar reactors, medicinally relevant molecules, such as ascaridole and an intermediate of artemisinin, were prepared as well.
- Cambié, Dario,Dobbelaar, Jeroen,Riente, Paola,Vanderspikken, Jochen,Shen, Chong,Seeberger, Peter H.,Gilmore, Kerry,Debije, Michael G.,No?l, Timothy
-
-
Read Online
- Coupling of boronic acids with amines in the presence of a supported copper catalyst
-
An efficient heterogeneous catalytic method was developed for Chan-Lam reaction, coupling of amines and boronic acid. Copper on 4 A molecular sieve provided yields comparable to the methods published. The method provides the main advantages of a heterogeneous catalytic procedure, the preparation of the catalyst is easy, the workup of the reaction mixture is simple. Graphical abstract: [Figure not available: see fulltext.]
- Debreczeni, Nora,Fodor, Anna,Hell, Zoltan
-
-
Read Online
- Well-defined allylnickel chloride/N-heterocyclic carbene [(NHC)Ni (allyl)Cl] complexes as highly active precatalysts for C-N and C-S cross-coupling reactions
-
The room temperature Buchwald-Hartwig amination of heteroaromatic chlorides has been achieved using the sterically bulky allylnickel chloride/ N-heterocyclic carbene [(IPr)Ni (allyl)Cl]complex as a well-defined precatalyst. Arylation of aromatic thiols, affording high yields of products under low catalyst loadings, has also been promoted with the same complex.
- Iglesias, Maria Jose,Prieto, Auxiliadora,Nicasioa, M. Carmen
-
-
Read Online
- Efficient C-N and C-S bond formation using the highly active [Ni(allyl)Cl(IPr*OMe)] precatalyst
-
Two new [Ni(allyl)Cl(NHC)] complexes with the bulky yet flexible N-heterocyclic carbene (NHC) ligands IPr* {N,N'-bis[2,6- bis(diphenylmethyl)-4-methylphenyl]imidazole-2-ylidene} and IPr* OMe {N,N'-bis[2,6-bis(diphenylmethyl)-4-methoxyphenyl]imidazol-2- ylidene} are reported. These complexes were employed in the amination and sulfination of aryl halide species and were shown to perform well in these reactions, which typically required less than half as much catalyst as previous state-of-the-art nickel complexes. Copyright
- Martin, Anthony R.,Nelson, David J.,Meiries, Sebastien,Slawin, Alexandra M.Z.,Nolan, Steven P.
-
-
Read Online
- Synthesis and catalytic activity of palladium complexes bearingN-heterocyclic carbenes (NHCs) and 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) ligands
-
The synthesis and characterization of novel palladium complexes bearingN-heterocyclic carbenes (NHCs) and 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) are reported. These organometallic complexes can be easily obtained using two different synthetic strategies that involve either the substitution of the pyridine ligand fromtrans-[Pd(NHC)(Py)Cl2] or by simple addition of the CAP ligand to dimeric species [Pd(NHC)Cl2]2. The mixed NHC/CAP complexes were tested as pre-catalysts in the Buchwald-Hartwig aryl amination coupling, showing good catalytic activity, especially in the case ofcis-[Pd(IPr)(CAP)Cl2].
- Beli?, Marek,Cazin, Catherine S. J.,Martynova, Ekaterina,Nolan, Steven P.,Scattolin, Thomas,Vanden Broeck, Sofie M. P.,Voloshkin, Vladislav A.
-
-
Read Online
- Development of an air-stable, broadly applicable nickel source for nickel-catalyzed cross-coupling
-
The synthesis of NiCl(o-tolyl)(TMEDA) (3; TMEDA = tetramethylethylenediamine) and its application in coupling reactions is described. In combination with a suitable ligand, precatalyst 3 was applied to a wide range of transformations, such as Suzuki, amination, Kumada, Negishi, Heck, borylation, and reductive coupling. Yields of products obtained with 3 are equal or superior to those obtained with common Ni sources such as Ni(cod)2 (1) and NiCl2(dme) (2). Importantly, and unlike 1, complex 3 is stable for months in air as a solid, which eliminates the need for a glovebox and greatly facilitates the reaction setup. Thus, complex 3 is the first highly versatile Ni source that combines the broad applicability of 1 with the air stability of 2.
- Magano, Javier,Monfette, Sebastien
-
-
Read Online
- Design of a Multiuse Photoreactor To Enable Visible-Light Photocatalytic Chemical Transformations and Labeling in Live Cells
-
Despite the growing use of visible-light photochemistry in both chemistry and biology, no general low-heat photoreactor for use across these different disciplines exists. Herein, we describe the design and use of a standardized photoreactor for visible-li
- Bissonnette, Noah B.,Ryu, Keun Ah,Reyes-Robles, Tamara,Wilhelm, Sharon,Tomlinson, Jake H.,Crotty, Kelly A.,Hett, Erik C.,Roberts, Lee R.,Hazuda, Daria J.,Jared Willis,Oslund, Rob C.,Fadeyi, Olugbeminiyi O.
-
-
Read Online
- Versatile Open-Source Photoreactor Architecture for Photocatalysis across the Visible Spectrum
-
Adoption of commercial photoreactors as standards for photocatalysis research could be limited by high cost. We report the development of the Wisconsin Photoreactor Platform (WPP), an open-source photoreactor architecture potentially suitable for general
- Lampkin, Philip P.,Thompson, Blaise J.,Gellman, Samuel H.
-
-
Read Online
- Electrochemical Cross-Dehydrogenative Aromatization Protocol for the Synthesis of Aromatic Amines
-
The introduction of amines onto aromatics without metal catalysts and chemical oxidants is synthetically challenging. Herein, we report the first example of an electrochemical cross-dehydrogenative aromatization (ECDA) reaction of saturated cyclohexanones and amines to construct anilines without additional metal catalysts and chemical oxidants. This reaction exhibits a broad scope of cyclohexanones including heterocyclic ketones, affording a variety of aromatic amines with various functionalities, and shows great potential in the synthesis of biologically active compounds.
- Tao, Shao-Kun,Chen, Shan-Yong,Feng, Mei-Lin,Xu, Jia-Qi,Yuan, Mao-Lin,Fu, Hai-Yan,Li, Rui-Xiang,Chen, Hua,Zheng, Xue-Li,Yu, Xiao-Qi
-
supporting information
p. 1011 - 1016
(2022/02/05)
-
- A Simple Synthetic Route to Well-Defined [Pd(NHC)Cl(1-tBu-indenyl)] Pre-catalysts for Cross-Coupling Reactions
-
The development of robust, more efficient, general, easily accessible Pd(II)–NHC pre-catalysts remains a key issue in cross-coupling applications. A selection of well-defined, air and moisture stable [Pd(NHC)Cl(1-tBu-indenyl)] (NHC=IPr, IPrCl, IMes, SIMes, IPr*) pre-catalysts have been synthesized in good to excellent yields by reacting [Pd(1-tBu-indenyl)(μ-Cl)]2 and various NHC?HCl precursors in the presence of the weak base K2CO3 in green acetone. The synthesized Pd(II)-NHC derivatives displayed excellent catalytic activity in classical Suzuki-Miyaura and Buchwald–Hartwig reactions, especially when IPrCl is employed as ancillary ligand. Additionally, in the challenging Suzuki-Miyaura reaction between esters and arylboronic acids, the [Pd(IPr*)Cl(1-tBu-indenyl)] complex exhibited the optimum catalytic activity under very mild reaction conditions.
- Liu, Yaxu,Scattolin, Thomas,Gobbo, Alberto,Beli?, Marek,Van Hecke, Kristof,Nolan, Steven P.,Cazin, Catherine S. J.
-
-
- Reagent and Catalyst Capsules: A Chemical Delivery System for Reaction Screening and Parallel Synthesis
-
Commercially available hydroxypropyl methylcellulose capsules are employed as a fast, safe, and user-friendly chemical delivery system containing all reagents (catalyst, ligand, and base) for three important transition-metal-catalyzed reactions: Buchwald-Hartwig, Suzuki-Miyaura, and metallophotoredox C-N cross-coupling reactions. This encapsulation methodology simplifies the screening of reaction conditions and the preparation of compound libraries using parallel synthesis in organic solvents or aqueous media. These reagents-containing HPMC capsules are easy to prepare, come in different sizes, and can be stored on the bench under noninert conditions.
- Borlinghaus, Niginia,Kaschel, Johannes,Klee, Johanna,Haller, Vanessa,Schetterl, Jasmin,Heitz, Stephanie,Lindner, Tanja,Dietrich, Justin D.,Braje, Wilfried M.,Jolit, Anais
-
p. 1357 - 1370
(2020/12/21)
-
- peri-Xanthenoxanthene (PXX): a Versatile Organic Photocatalyst in Organic Synthesis
-
Recent years have witnessed a continuous development of photocatalysts to satisfy the growing demand of photophysical and redox properties in photoredox catalysis, with complex structures or alternative strategies devised to access highly reducing or oxidising systems. We report herein the use of peri-xanthenoxanthene (PXX), a simple and inexpensive dye, as an efficient photocatalyst. Its highly reducing excited state allows activation of a wide range of substrates, thus triggering useful radical reactions. Benchmark transformations such as the addition of organic radicals, generated by photoreduction of organic halides, to radical traps are initially demonstrated. More complex dual catalytic manifolds are also shown to be accessible: the β-arylation of cyclic ketones is successful when using a secondary amine as organocatalyst, while cross-coupling reactions of aryl halides with amines and thiols are obtained when using a Ni co-catalyst. Application to the efficient two-step synthesis of the expensive fluoro-tetrahydro-1H-pyrido[4,3-b]indole, a crucial synthetic intermediate for the investigational drug setipiprant, has been also demonstrated. (Figure presented.).
- Pezzetta, Cristofer,Folli, Andrea,Matuszewska, Oliwia,Murphy, Damien,Davidson, Robert W. M.,Bonifazi, Davide
-
supporting information
p. 4740 - 4753
(2021/04/09)
-
- Amination of Aryl Halides Mediated by Electrogenerated Nickel from Sacrificial Anode
-
Electrochemical C(sp2)?N couplings mediated by nickel salts generated from the sacrificial anode has been described for the first time. In this approach, the sacrificial nickel anode is employed as the sole source of nickel and the process, operationally simple to set up, enables the preparation of functionalized arylamine derivatives with moderate to good yields, under mild reaction conditions and without additional ligand. A cooperative process between the two electrodes is involved in the proposed mechanism.
- Daili, Farah,Sengmany, Stéphane,Léonel, Eric
-
p. 2462 - 2469
(2021/06/28)
-
- Coupling of Alternating Current to Transition-Metal Catalysis: Examples of Nickel-Catalyzed Cross-Coupling
-
The coupling of transition-metal to photoredox catalytic cycles through single-electron transfer steps has become a powerful tool in the development of catalytic processes. In this work, we demonstrated that transition-metal catalysis can be coupled to al
- Bortnikov, Evgeniy O.,Semenov, Sergey N.
-
supporting information
p. 782 - 793
(2020/12/01)
-
- AIR-STABLE NI(0)-OLEFIN COMPLEXES AND THEIR USE AS CATALYSTS OR PRECATALYSTS
-
The present invention relates to air stable, binary Ni(0)-olefin complexes and their use in organic synthesis.
- -
-
Page/Page column 18-19
(2021/02/05)
-
- General Paradigm in Photoredox Nickel-Catalyzed Cross-Coupling Allows for Light-Free Access to Reactivity
-
Self-sustained NiI/III cycles are established as a potentially general paradigm in photoredox Ni-catalyzed carbon–heteroatom cross-coupling reactions through a strategy that allows us to recapitulate photoredox-like reactivity in the absence of light across a wide range of substrates in the amination, etherification, and esterification of aryl bromides, the latter of which has remained, hitherto, elusive under thermal Ni catalysis. Moreover, the accessibility of esterification in the absence of light is especially notable because previous mechanistic studies on this transformation under photoredox conditions have unanimously invoked energy-transfer-mediated pathways.
- Nocera, Daniel G.,Qin, Yangzhong,Sun, Rui
-
supporting information
p. 9527 - 9533
(2020/04/08)
-
- Solar-driven tandem photoredox nickel-catalysed cross-coupling using modified carbon nitride
-
Nickel-catalysed aryl amination and etherification are driven with sunlight using a surface-modified carbon nitride to extend the absorption of the photocatalyst into a wide range of the visible region. In contrast to traditional homogeneous photochemical methodologies, the lower cost and higher recyclability of the metal-free photocatalyst, along with the use of readily available sunlight, provides an efficient and sustainable approach to promote nickel-catalysed cross-couplings. This journal is
- Qin, Yangzhong,Martindale, Benjamin C. M.,Sun, Rui,Rieth, Adam J.,Nocera, Daniel G.
-
p. 7456 - 7461
(2020/08/03)
-
- Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters
-
The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.
- Malapit, Christian A.,Borrell, Margarida,Milbauer, Michael W.,Brigham, Conor E.,Sanford, Melanie S.
-
supporting information
p. 5918 - 5923
(2020/04/08)
-
- Visible Light-Mediated (Hetero)aryl Amination Using Ni(II) Salts and Photoredox Catalysis in Flow: A Synthesis of Tetracaine
-
We report a visible light-mediated flow process for C-N cross-coupling of (hetero)aryl halides with a variety of amine coupling partners through the use of a photoredox/nickel dual catalyst system. Compared to the method in batch, this flow process enables a broader substrate scope, including less-activated (hetero)aryl bromides and electron-deficient (hetero)aryl chlorides, and significantly reduced reaction times (10 to 100 min). Furthermore, scale up of the reaction, demonstrated through the synthesis of tetracaine, is easily achieved, delivering the C-N cross-coupled products in consistently high yield of 84% on up to a 10 mmol scale.
- Park, Boyoung Y.,Pirnot, Michael T.,Buchwald, Stephen L.
-
p. 3234 - 3244
(2020/02/04)
-
- Ni(COD)(DQ): An Air-Stable 18-Electron Nickel(0)–Olefin Precatalyst
-
We report that Ni(COD)(DQ) (COD=1,5-cyclooctadiene, DQ=duroquinone), an air-stable 18-electron complex originally described by Schrauzer in 1962, is a competent precatalyst for a variety of nickel-catalyzed synthetic methods from the literature. Due to its apparent stability, use of Ni(COD)(DQ) as a precatalyst allows reactions to be conveniently performed without use of an inert-atmosphere glovebox, as demonstrated across several case studies.
- Apolinar, Omar,Derosa, Joseph,Eastgate, Martin D.,Engle, Keary M.,Joannou, Matthew V.,Li, Zi-Qi,Tran, Van T.,Wisniewski, Steven R.
-
supporting information
p. 7409 - 7413
(2020/04/10)
-
- Energy Transfer to Ni-Amine Complexes in Dual Catalytic, Light-Driven C-N Cross-Coupling Reactions
-
Dual catalytic light-driven cross-coupling methodologies utilizing a Ni(II) salt with a photocatalyst (PC) have emerged as promising methodologies to forge aryl C-N bonds under mild conditions. The recent discovery that the PC can be omitted and the Ni(II) complex directly photoexcited suggests that the PC may perform energy transfer (EnT) to the Ni(II) complex, a mechanistic possibility that has recently been proposed in other systems across dual Ni photocatalysis. Here, we report the first studies in this field capable of distinguishing EnT from electron transfer (ET), and the results are consistent with F?rster-type EnT from the excited state [Ru(bpy)3]Cl2 PC to Ni-amine complexes. The structure and speciation of Ni-amine complexes that are the proposed EnT acceptors were elucidated by crystallography and spectroscopic binding studies. With the acceptors known, quantitative F?rster theory was utilized to predict the ratio of quenching rate constants upon changing the PC, enabling selection of an organic phenoxazine PC that proved to be more effective in catalyzing C-N cross-coupling reactions with a diverse selection of amines and aryl halides.
- Kudisch, Max,Lim, Chern-Hooi,Thordarson, Pall,Miyake, Garret M.
-
supporting information
p. 19479 - 19486
(2019/12/25)
-
- METHODS FOR FORMING ARYL CARBON-NITROGEN BONDS USING LIGHT AND PHOTOREACTORS USEFUL FOR CONDUCTING SUCH REACTIONS
-
The disclosure relates to a method for forming aryl carbon-nitrogen bonds and to photoreactors useful in these and other light-driven reactions. The method comprises contacting an aryl halide with an amine in the presence of a Ni salt catalyst solution and an optional base, thereby forming a reaction mixture; exposing the reaction mixture to light under reaction condition sufficient to produce the aryl carbon-nitrogen bonds. In certain embodiments, the amine may be present in a molar excess to the aryl halide. In certain embodiments, the Ni salt catalyst solution includes a Ni(II) salt and a polar solvent, wherein the Ni(II) salt is dissolved in the polar solvent. In certain embodiments, the reactions conditions include holding the reaction mixture at between about room temperature and about 80° C. for between about 1 hour and about 20 hours such that at least about 50% yield is obtained.
- -
-
Paragraph 0097-0098; 0110-0111
(2019/11/22)
-
- Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes
-
Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
- Ghosh, Indrajit,Khamrai, Jagadish,Savateev, Aleksandr,Shlapakov, Nikita,Antonietti, Markus,K?nig, Burkhard
-
p. 360 - 366
(2019/08/15)
-
- Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines
-
Herein, we describe a new catalytic approach to accessing aromatic amines from an abundant feedstock, namely phenols. The most reliable catalytic method for converting phenols to aromatic amines uses an activating group, such as a trifluoromethane sulfonyl group. However, this activating group is eliminated as a leaving group during the amination process, resulting in significant waste. Our nickel-catalyzed decarboxylation reaction of aryl carbamates forms aromatic amines with carbon dioxide as the only byproduct. As this amination proceeds in the absence of free amines, a range of functionalities, including a formyl group, are compatible. A bisphosphine ligand immobilized on a polystyrene support (PS-DPPBz) is key to the success of this reaction, generating a catalytic species that is significantly more active than simple nonsupported variants.
- Nishizawa, Akihiro,Takahira, Tsuyoshi,Yasui, Kosuke,Fujimoto, Hayato,Iwai, Tomohiro,Sawamura, Masaya,Chatani, Naoto,Tobisu, Mamoru
-
supporting information
p. 7261 - 7265
(2019/05/16)
-
- [Pd(4-R3Si-IPr)(allyl)Cl], a Family of Silyl-Substituted Pd-NHC Complexes: Catalytic Systems for the Buchwald-Hartwig Amination
-
A family of Pd-IPr complexes (1Pd-6Pd) featuring electropositive and bulky R3Si substituents at the 4-position of the NHC ring was prepared and fully characterized. The catalytic performance of 1Pd (R3Si = SiMe3) and 3Pd (R3Si = Si(allyl)Me2) in the Buchwald-Hartwig amination was excellent, notably outperforming those of other previously reported catalytic systems by requiring shorter reaction times, lower catalyst loadings, and milder reaction conditions. Furthermore, a systematic evaluation of both the electronic and steric influences of the 4-R3Si-IPr ligand on the overall catalytic performance of 1Pd-6Pd revealed that electronic rather than steric factors play a dominant role.
- Fukaya, Norihisa,Mizusaki, Tomoteru,Hatakeyama, Kouhei,Seo, Yuto,Inaba, Yuuya,Matsumoto, Kazuhiro,Lee, Vladimir Ya.,Takagi, Yukio,Kuwabara, Junpei,Kanbara, Takaki,Choe, Yoong-Kee,Choi, Jun-Chul
-
p. 375 - 384
(2019/01/11)
-
- [Pd(IPr*R)(acac)Cl]: Efficient bulky Pd-NHC catalyst for Buchwald-Hartwig C-N cross-coupling reaction
-
A series of bulky palladium catalysts based on N-heterocyclic carbene, (Pd(NHC)(acac)Cl: NHC = IPr*me = N,N′-bis(2,6-bis(di-p-tolylmethyl)-4-methylphenyl)-imidazol-2 -ylidene, Pd(IPr*me)(acac)Cl; NHC = IPr*ipr = N,N′-bis(2,6-bis(di-4-isopropylphenyl)-4-methylphenyl)-imidazol-2 -ylidene, Pd(IPr*ipr)(acac)Cl; and NHC = IPr*tBu = N,N′-bis(2,6-bis(di-4-(tert-butyl)phenyl)- 4-methylphenyl)- imidazol-2-ylidene, Pd(IPr*tBu)(acac)Cl; acac = acetylacetonate), have been designed and synthesized. These three new catalysts showed much better catalytic activity in the Buchwald?Hartwig arylamination coupling reaction as compare to the earlier congener (IPr*)Pd(acac)Cl (IPr* = N,N′-bis(2,6-diphenylmethyl)-4-methylphenylimidazol-2-ylidene). The highly active PdII precatalyst [Pd(IPr*me)(acac)Cl] has been fully explored by using a wide range of substrates with different electronic and steric demands of coupling partners, for which up to 99% isolated yields were obtained. Remarkably, the moderate isolated yield was obtained for the challenging coupling of the amine bearing very bulky groups.
- Tian, Xiabing,Lin, Jing,Zou, Sheng,Lv, Junwei,Huang, Qingfei,Zhu, Jin,Huang, Shuping,Wang, Qiwei
-
supporting information
p. 125 - 130
(2018/03/06)
-
- C-N Cross-Coupling via Photoexcitation of Nickel-Amine Complexes
-
C-N cross-coupling is an important class of reactions with far-reaching impacts across chemistry, materials science, biology, and medicine. Transition metal complexes can elegantly orchestrate diverse aminations but typically require demanding reaction conditions, precious metal catalysts, or oxygen-sensitive procedures. Here, we introduce a mild nickel-catalyzed C-N cross-coupling methodology that operates at room temperature using an inexpensive nickel source (NiBr2·3H2O), is oxygen tolerant, and proceeds through direct irradiation of the nickel-amine complex. This operationally robust process was employed for the synthesis of diverse C-N-coupled products (40 examples) by irradiating a solution containing an amine, an aryl halide, and a catalytic amount of NiBr2·3H2O with a commercially available 365 nm LED at room temperature without added photoredox catalyst and the amine substrate serving additional roles as the ligands and base. Density functional theory calculations and kinetic isotope effect experiments were performed to elucidate the observed C-N cross-coupling reactivity.
- Lim, Chern-Hooi,Kudisch, Max,Liu, Bin,Miyake, Garret M.
-
supporting information
p. 7667 - 7673
(2018/05/31)
-
- Buchwald-Hartwig amination using Pd(i) dimer precatalysts supported by biaryl phosphine ligands
-
We report the synthesis of air-stable Pd(i) dimer complexes featuring biaryl phosphine ligands. Catalytic experiments suggest that these complexes are competent precatalysts that can mediate cross-coupling amination reactions between aryl halides with bot
- Kirlikovali, Kent O.,Cho, Eunho,Downard, Tyler J.,Grigoryan, Lilit,Han, Zheng,Hong, Sooji,Jung, Dahee,Quintana, Jason C.,Reynoso, Vanessa,Ro, Sooihk,Shen, Yi,Swartz, Kevin,Ter Sahakyan, Elizabeth,Wixtrom, Alex I.,Yoshida, Brandon,Rheingold, Arnold L.,Spokoyny, Alexander M.
-
supporting information
p. 3684 - 3688
(2018/03/21)
-
- Direct Borylation of Tertiary Anilines via C-N Bond Activation
-
The first successful catalytic borylation of unactivated aromatic C-N bonds of tertiary anilines without the preactivation or any directing groups is demonstrated. The reactivity of both N,N-dialkylarylamines and N-arylpyrroles were investigated systematically, and the targeted products were furnished in moderate to good yields. The DFT calculation results indicated that the catalytic cycle is furnished via a five-membered cyclic transition-state due to the steric hindrance of the Ni/NHC catalytic system.
- Cao, Zhi-Chao,Li, Xiao-Lei,Luo, Qin-Yu,Fang, Huayi,Shi, Zhang-Jie
-
supporting information
p. 1995 - 1998
(2018/04/16)
-
- Complementary site-selectivity in arene functionalization enabled by overcoming the ortho constraint in palladium/norbornene catalysis
-
Achieving site-selectivity in arene functionalization that is complementary to the site-selectivity from electrophilic aromatic substitution reactions has been a long-standing quest in organic synthesis. Palladium/norbornene cooperative catalysis potentia
- Wang, Jianchun,Li, Renhe,Dong, Zhe,Liu, Peng,Dong, Guangbin
-
p. 866 - 872
(2018/06/30)
-
- Synergistic Ligand Effect between N-Heterocyclic Carbene (NHC) and Bicyclic Phosphoramidite (Briphos) Ligands in Pd-Catalyzed Amination
-
A synergistic ligand effect between NHC and phosphorus ligands in Pd-catalyzed Buchwald-Hartwig amination reactions was demonstrated with tunable π-acceptor bicyclic bridgehead phosphoramidite (briphos) ligands. The catalytic activity of NHC-Pd-L (L = phosphorus ligand) precatalysts depends on the electronic properties of L. A NHC-Pd-L catalyst with an N-cyclohexyl-substituted briphos ligand was found to be highly efficient. A series of C-N bond coupling reactions between primary or secondary amines and aryl chlorides were performed with high yields under mild reaction conditions.
- Kim, Miji,Shin, Taeil,Lee, Ansoo,Kim, Hyunwoo
-
supporting information
p. 3253 - 3258
(2018/10/02)
-
- NIXANTPHOS: A highly active ligand for palladium catalyzed Buchwald-Hartwig amination of unactivated aryl chlorides
-
Xantphos is one of the two most common ligands used in palladium catalyzed Buchwald-Hartwig amination reactions, because of its broad scope and high probability of success. It does not, however, work well with unactivated aryl chlorides. Herein NIXANTPHOS is compared to Xantphos and an array of mono- and bidentate phosphines. NIXANTPHOS outperforms Xantphos and all other bidentate ligands examined. Under the optimal reaction conditions, unactivated aryl chlorides afford the expected products in good to excellent yield with as low as 0.05 mol% (500 ppm) palladium loading.
- Mao, Jianyou,Zhang, Jiadi,Zhang, Shuguang,Walsh, Patrick J.
-
supporting information
p. 8690 - 8696
(2018/07/13)
-
- Strongly Reducing, Visible-Light Organic Photoredox Catalysts as Sustainable Alternatives to Precious Metals
-
Photoredox catalysis is a versatile approach for the construction of challenging covalent bonds under mild reaction conditions, commonly using photoredox catalysts (PCs) derived from precious metals. As such, there is need to develop organic analogues as sustainable replacements. Although several organic PCs have been introduced, there remains a lack of strongly reducing, visible-light organic PCs. Herein, we establish the critical photophysical and electrochemical characteristics of both a dihydrophenazine and a phenoxazine system that enables their success as strongly reducing, visible-light PCs for trifluoromethylation reactions and dual photoredox/nickel-catalyzed C?N and C?S cross-coupling reactions, both of which have been historically exclusive to precious metal PCs.
- Du, Ya,Pearson, Ryan M.,Lim, Chern-Hooi,Sartor, Steven M.,Ryan, Matthew D.,Yang, Haishen,Damrauer, Niels H.,Miyake, Garret M.
-
supporting information
p. 10962 - 10968
(2017/08/22)
-
- Electrochemically Enabled, Nickel-Catalyzed Amination
-
Along with amide bond formation, Suzuki cross-coupling, and reductive amination, the Buchwald–Hartwig–Ullmann-type amination of aryl halides stands as one of the most employed reactions in modern medicinal chemistry. The work herein demonstrates the potential of utilizing electrochemistry to provide a complementary avenue to access such critical bonds using an inexpensive nickel catalyst under mild reaction conditions. Of note is the scalability, functional-group tolerance, rapid rate, and the ability to employ a variety of aryl donors (Ar?Cl, Ar?Br, Ar?I, Ar?OTf), amine types (primary and secondary), and even alternative X?H donors (alcohols and amides).
- Li, Chao,Kawamata, Yu,Nakamura, Hugh,Vantourout, Julien C.,Liu, Zhiqing,Hou, Qinglong,Bao, Denghui,Starr, Jeremy T.,Chen, Jinshan,Yan, Ming,Baran, Phil S.
-
supporting information
p. 13088 - 13093
(2017/09/25)
-
- Nickel-Catalyzed Amination of Aryl 2-Pyridyl Ethers via Cleavage of the Carbon-Oxygen Bond
-
Reaction of aryl 2-pyridyl ethers with amines was carried out via Ni-catalyzed C-OPy bond cleavage, giving aniline derivatives in reasonable to excellent yields. Both electron-rich and electron-poor aryl 2-pyridyl ethers and a wide range of amines can be used in the transformation. The method provides a conversion way for the 2-pyridyloxy directing group in the C-H bond functionalization reactions.
- Li, Jing,Wang, Zhong-Xia
-
supporting information
p. 3723 - 3726
(2017/07/26)
-
- NI(0) CATALYSTS
-
Provided herein are nickel(O) catalysts that are stable when exposed to air and can be used to catalyze the formation of a C-C, C-O, or C-N bond.
- -
-
Paragraph 0023; 0068; 0069
(2017/07/31)
-
- Metal-free Synthesis of Aryl Amines: Beyond Nucleophilic Aromatic Substitution
-
A mild and metal-free approach to C?N coupling is described that employs diaryliodonium salt electrophiles and secondary aliphatic amine nucleophiles. This reaction results in direct ipso-substitution of the iodonium moiety and unsymmetrical aryl(TMP)iodonium salts are primarily employed. Moreover, arene substituents and substitution patterns that currently pose a challenge to classical metal-free methods are accommodated and the alicyclic amine nucleophiles used here are unprecedented in other contemporary metal-free C?N coupling reactions.
- Sandtorv, Alexander H.,Stuart, David R.
-
supporting information
p. 15812 - 15815
(2016/12/16)
-
- A Bis(silylene)-Substituted ortho-Carborane as a Superior Ligand in the Nickel-Catalyzed Amination of Arenes
-
The synthesis and structure of the first 1,2-bis(NHSi)-substituted ortho-carborane [(LSi:)C]2B10H10(termed SiCCSi) is reported (NHSi=N-heterocyclic silylene; L=PhC(NtBu)2). Its suitability to serve as a reliable bis(silylene) chelating ligand for transition metals is demonstrated by the formation of [SiCCSi]NiBr2and [SiCCSi]Ni(CO)2complexes. The CO stretching vibration modes of the latter indicate that the SiIIatoms in the SiCCSi ligand are even stronger σ donors than the PIIIatoms in phosphines and CIIatoms in N-heterocyclic carbene (NHC) ligands. Moreover, the strong donor character of the [SiCCSi] ligand enables [SiCCSi]NiBr2to act as an outstanding precatalyst (0.5 mol % loading) in the catalytic aminations of arenes, surpassing the activity of previously known molecular Ni-based precatalysts (1–10 mol %).
- Zhou, Yu-Peng,Raoufmoghaddam, Saeed,Szilvási, Tibor,Driess, Matthias
-
supporting information
p. 12868 - 12872
(2016/10/04)
-
- Buchwald-Hartwig amination reaction using supported palladium on phosphine-functionalized magnetic nanoparticles
-
The supported palladium on phosphine-functionalized magnetic nanoparticles (Pd-PFMN) was found to be an efficient magnetically separable catalyst for the Buchwald-Hartwig amination reaction (BHAR) under solvent-free conditions. All of the reactions in the presence of Pd-PFMN catalyst afforded the corresponding products in good to excellent yields. The catalyst can be easily separated from the reaction mixture using an external magnetic field, and it can be reused at least five cycles without significant loss in its initial catalytic activity.
- Zarnaghash, Narges,Panahi, Farhad,Khalafi-Nezhad, Ali
-
p. 2057 - 2064
(2015/10/06)
-
- Palladium-catalyzed amination of aryl sulfides with aliphatic amines
-
Conditions for the palladium-NHC-catalyzed amination of aryl sulfides with aliphatic as well as aromatic amines were established. The KHMDS-mediated amination of heteroaryl sulfides could proceed without palladium. Based on the distinct difference in reactivity of C-Br and C-S bonds, a sequential amination of bromothioanisole can take place to install two different alkylamino groups onto the aromatic ring in one pot. A palladium-NHC precatalyst shows high efficiency for C-S bond cleavage for the amination of aryl sulfides with aliphatic amines or aromatic amines.
- Gao, Ke,Yorimitsu, Hideki,Osuka, Atsuhiro
-
supporting information
p. 2678 - 2682
(2015/04/27)
-
- Two cadmium(II) complexes with oxazoline-based ligands as effective catalysts for C-N cross-coupling reactions
-
Binuclear [{(DMOX)CdCl}2(μ-Cl)2] (DMOX = 4,5-dihydro-2-(4,5-dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyl-oxazole) (1) and mononuclear [(Dm-Pybox)CdCl2] (Dm-Pybox = 2,6-bis[4′,4′-dimethyloxazolin-2′-yl]pyridine) (2) were obtained by reacting CdCl2 with DMOX and Dm-Pybox ligands, respectively. In the solid state, the supramolecular structures of 1 and 2 feature helical chains fabricated by C-H-Cl hydrogen bond interactions. The C-N cross-coupling reactions catalyzed by the two complexes were also investigated in homogeneous system. The results show that binuclear complex 1 exhibit significantly enhanced catalytic activity for C-N cross-coupling reactions.
- Jia, Wei-Guo,Li, Dan-Dan,Gu, Cuiping,Dai, Yuan-Chen,Zhou, Ying-Hua,Yuan, Guozan,Sheng, En-Hong
-
p. 226 - 231
(2015/02/05)
-
- Nickel-catalyzed cross-coupling of aryltrimethylammonium triflates and amines
-
Nickel-catalyzed cross-coupling of aryltrimethylammonium triflates and amines was carried out under mild conditions. The reaction has a broad scope of substrates and can be performed by a one-pot procedure from an aryldimethylamine.
- Zhang, Xue-Qi,Wang, Zhong-Xia
-
p. 1448 - 1453
(2014/03/21)
-
- Nickel-catalyzed amination of aryl chlorides and sulfamates in 2-methyl-THF
-
The nickel-catalyzed amination of aryl O-sulfamates and chlorides using the green solvent 2-methyl-THF is reported. This methodology employs the commercially available and air-stable precatalyst NiCl2(DME), is broad in scope, and provides access to aryl amines in synthetically useful yields. The utility of this methodology is underscored by examples of gram-scale couplings conducted with catalyst loadings as low as 1 mol % nickel. Moreover, the nickel-catalyzed amination described is tolerant of heterocycles and should prove useful in the synthesis of pharmaceutical candidates and other heteroatom-containing compounds.
- Fine Nathel, Noah F.,Kim, Junyong,Hie, Liana,Jiang, Xingyu,Garg, Neil K.
-
p. 3289 - 3293
(2015/02/19)
-
- Nickel-catalyzed coupling of fluoroarenes and amines
-
The combination of bis(cyclooctadiene)nickel [Ni(COD)2] and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene hydrochloride (IPr×HCl) effectively catalyzes coupling of fluoroarenes with amines in the presence of sodium tert-butoxide (t-BuONa). A
- Zhu, Feng,Wang, Zhong-Xia
-
p. 3694 - 3702
(2014/01/06)
-
- Copper-catalyzed aerobic oxidative amination of arylboronic acid with aminal under base-free conditions
-
A new process involving copper-catalyzed oxidative amination reaction of various arylboronic acids with aminals under mild conditions has been developed. The key copper-amide species involved in the C-N bond-forming process was generated via C-N bond cleavage of aminal under base-free conditions. Moderate yields of desired amination products can be obtained under mild conditions when air was served as oxidant and PhCO2H was used as an additive.
- Zhou, Yanping,Xie, Yinjun,Yang, Lei,Xie, Pan,Huang, Hanmin
-
supporting information
p. 2713 - 2716
(2013/06/05)
-
- Novel robust benzimidazolylidene palladium complexes: Synthesis, structure, and catalytic applications in amination of chloroarenes
-
A series of novel pyridine stabilized PdeNHC complexes were developed, which revealed high activities and broad substrates tolerance in the amination of various (hetero)-aryl chlorides. Besides various secondary amines, a wide range of primary anilines and aliphatic amines were also well tolerated. The results highlight us a new strategy to increase catalyst activity in the future catalyst design by alternating the σ-donor property and flexibility of NHC ligands.
- Fang, Weiwei,Jiang, Jian,Xu, Yong,Zhou, Juefei,Tu, Tao
-
p. 673 - 679
(2013/07/27)
-
- New phosphine-functionalized NHC ligands: Discovery of an effective catalyst for the room-temperature amination of aryl chlorides with primary and secondary amines
-
We report convenient and high-yielding syntheses of new phosphine-functionalized dihydroimidazolium salts and demonstrate their utility as ligand precursors for Buchwald-Hartwig amination. Several examples of the general formula [1-Mes-3-{2-(PR2)phenyl}imidazolidin-2-ylium][BF 4] have been prepared, where phosphines of varying steric and electronic properties (R = Ph (9), Cy (10), 1-Ad (11)) are tethered by an o-phenylene group. The synthesis was not adaptable to N-aryl groups other than mesityl, giving unexpected phosphonium salt species instead. The synthesis was adapted to flexible benzyl-linked variants of the formula [1-Ar-3-{2-(PCy 2)benzyl}imidazolidin-2-ylium][BF4], which allowed more steric variation of the dihydroimidazolium N-aryl group (Ar = Mes (21), Dipp (22)). A preliminary study of these hybrid NHC/P ligands in Buchwald-Hartwig amination catalysis (in situ precatalyst formation) revealed 11 to be the most active of the series. Premixing the isolated free NHC ligand 1-Mes-3-{2-(PAd2)phenyl}imidazolidin-2-ylidene (23) with [Pd(cinnamyl)Cl]2 provided a highly active precatalyst that performed well at room temperature and 1 mol % catalyst loading. The system was shown to have an unprecedented ability to arylate both primary alkylamines (monoarylation) and secondary dialkylamines with aryl chlorides at room temperature. Electron-rich and -poor aryl and heteroaryl halides, as well as those featuring ortho substitution, were well tolerated, while substrates featuring both primary and secondary amine groups were selectively arylated at the NH2 position. Furthermore, a preliminary examination of performance in ammonia arylation and acetone α-arylation showed promising results, giving good conversion and high selectivity for monoarylation in both cases.
- Wheaton, Craig A.,Bow, John-Paul J.,Stradiotto, Mark
-
p. 6148 - 6161
(2013/12/04)
-