- Formal [4+3], [4+2], [4+1] and [2+1] cycloadditions and acid-base reaction of 2-methyl-1,3-dimorpholino-1,3-butadiene with Fischer carbene complexes
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2-Methyl-1,3-dimorpholino-1,3-butadiene 1 reacted with α,β-unsaturated Fischer carbene complexes to give a wide range of different products depending on the substitution pattern. Thus, seven-membered rings (4, 5 and 6) could be obtained from chromium comp
- Barluenga, Jose,Aznar, Fernando,Fernandez, Monica
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- Synthesis of N-heterocyclic carbene-Pd(II)-5-phenyloxazole complexes and initial studies of their catalytic activity toward the Buchwald-Hartwig amination of aryl chlorides
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Three new N-heterocyclic carbene (NHC)-Pd(II) complexes using 5-phenyloxazole as the ancillary ligand have been obtained in moderate to good yields by a one-pot reaction of the corresponding imidazolium salts, palladium chloride and 5-phenyloxazole under mild conditions. Initial studies showed that one of the complexes is an efficient catalyst for the Buchwald-Hartwig amination of aryl chlorides with various secondary and primary amines under the varied catalyst loading of 0.01-0.05 mol%, thus it will enrich the chemistry of NHCs and give an alternative catalyst for the coupling of challenging while cost-low aryl chlorides.
- Zhang, Zhi-Mao,Xu, Yu-Ting,Shao, Li-Xiong
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- Product selective reaction controlled by the combination of palladium nanoparticles, continuous microwave irradiation, and a co-existing solid; ligand-free Buchwald-Hartwig aminationvs.aryne amination
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We have developed a continuous microwave irradiation-assisted Buchwald-Hartwig amination using our original Pd nanoparticle catalyst with a copper plate as a co-existing metal solid. In this methodology, a microwave-controlled product selectivity was achieved between Buchwald-Hartwig amination and aryne amination performed under strongly basic conditions and at a high reaction temperature, because a polar chemical species such as Ar-Pd-halogen might be activated selectively by microwave radiation. Moreover, our catalyst could be used repeatedly over 10 times, and the amount of Pd leaching could be suppressed to a low level.
- Akiyama, Toshiki,Arai, Masayoshi,Arisawa, Mitsuhiro,Haneoka, Hitoshi,Harada, Kazuo,Murai, Kenichi,Murakami, Yosuke,Ohki, Yuuta,Ohta, Ryousuke,Sako, Makoto,Sirimangkalakitti, Natchanun,Suzuki, Takeyuki,Takahashi, Naoyuki,Takehara, Tsunayoshi,Yamada, Makito
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supporting information
p. 8131 - 8137
(2021/10/29)
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- Coupling of Alternating Current to Transition-Metal Catalysis: Examples of Nickel-Catalyzed Cross-Coupling
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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.
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supporting information
p. 782 - 793
(2020/12/01)
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- Catalyst-free photoinduced selective oxidative C(sp3)-C(sp3) bond cleavage in arylamines
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Due to the directional nature of sp3-hybridized orbitals and the absence of π-orbitals, the oxidative cleavage of the kinetically and thermodynamically stable C(sp3)-C(sp3) bond is extremely difficult and remains scarcely explored. In this work, under the double argument of quantum mechanics (QM) computations and meticulous experiments on our well-designed C-C single bond cleavage mechanism, we discovered a means of photoinduced selective oxidative C(sp3)-C(sp3) bond cleavage in arylamines, easily achieved by simple visible light irradiation using O2as a benign oxidant under very mild conditions. The utility of our methodology was demonstrated by the C(sp3)-C(sp3) bond cleavage in morpholine/piperazine arylamines with excellent functional group tolerance. Importantly, our methodology is noteworthy, not only in that it does not require any catalysts, but also in that it provides valuable possibilities for the scalable functionalization of clinical drugs and natural products.
- Duan, Wentao,Lian, Qi,Wang, Songping,Wei, Wentao,Zhou, Jingwei
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supporting information
p. 3261 - 3267
(2021/05/21)
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- Morpholine derivative oxidation ring-opening method and product thereof
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The invention relates to a morpholine derivative oxidation ring-opening method and a product thereof, and belongs to the technical field of compound preparation. The method for promoting oxidative cracking of C (sp3)-C (sp3) bonds of a morpholine derivative by visible light has been successfully developed under the inspiration of the design concept of visible light induced C (sp3)-C (sp3) bond cracking. According to the morpholine derivative oxidation ring-opening method, C (sp3)-C (sp3) bonds without ring stress are cracked by using visible light as an energy source and O2 as a final oxidizing agent, use of transition metal, high temperature, high pressure and chemical equivalent dangerous oxidizing agents is avoided, good functional group tolerance is established, 30 substrates are obtained, the yield is as high as 83%, and a supplementary scheme is provided for realizing oxidative cracking of the morpholine derivative under a mild condition.
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Paragraph 0039; 0046-0048
(2021/07/08)
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- Visible-Light-Mediated Aerobic Oxidative C(sp3)?C(sp3) Bond Cleavage of Morpholine Derivatives Using 4CzIPN as a Photocatalyst
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Herein, a metal-free strategy for the aerobic oxidative cleavage of the inert C(sp3)?C(sp3) bond was developed. Deconstruction of morpholine derivatives was conducted using visible light as an energy source and O2 as an oxidant under mild conditions. This procedure demonstrated suitable selectivity and functional group tolerance. Moreover, a possible mechanism involving a radical process was proposed based on a series of mechanism exploration and control experiments. (Figure presented.).
- Dong, Chun-Lin,Huang, Lan-Qian,Guan, Zhi,Huang, Chu-Sheng,He, Yan-Hong
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supporting information
p. 3803 - 3811
(2021/06/28)
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- Selective electrochemical: Para -thiocyanation of aromatic amines under metal-, oxidant- And exogenous-electrolyte-free conditions
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An electrochemical oxidative para-C-H-thiocyanation of aromatic amines has been developed to construct thiocyanato aromatic compounds under metal-, oxidant-, and exogenous-electrolyte-free conditions in an undivided cell. The transformation is compatible
- Zhang, Ying,Gao, Huanjie,Guo, Jiabao,Zhang, Hao,Yao, Xiaoquan
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supporting information
p. 13166 - 13169
(2021/12/20)
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- Effect of Precatalyst Oxidation State in C-N Cross-Couplings with 2-Phosphinoimidazole-Derived Bimetallic Pd(I) and Pd(II) Complexes
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We report the catalytic activity of two phosphinoimidazole-derived bimetallic palladium complexes in Pd-catalyzed amination reactions. Our studies demonstrate that the starting oxidation state (Pd(I) or Pd(II)) of the dimeric complex has a significant effect on the efficiency of the catalytic reaction. The corresponding Pd(I) complex shows higher reactivity in Buchwald-Hartwig aminations, while the Pd(II) complex is much more reactive in carbonylative amination reactions. These new dimeric palladium complexes provide good to excellent reactivity and yields in the amination reactions tested.
- Martinez, Erin E.,Moreno, Mariur Rodriguez,Barksdale, Caleb A.,Michaelis, David J.
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supporting information
p. 2763 - 2767
(2021/08/27)
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- Aryl-Diadamantyl Phosphine Ligands in Palladium-Catalyzed Cross-Coupling Reactions: Synthesis, Structural Analysis, and Application
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Synthesis, temperature-dependent NMR structure investigation and utilization of a new, stable and easily accessible aryl-diadamantylphosphine ligand family is reported. The bulky and electron-rich phosphorus center of the ligand enhances the catalytic activity of palladium in cross-coupling reactions of sterically demanding ortho-substituted aryl halides. In our study, we demonstrated the synthetic applicability of the new phosphine ligands in Buchwald-Hartwig and tosyl hydrazone coupling reactions.
- Sinai, ádám,Simkó, Dániel Cs.,Szabó, Fruzsina,Paczal, Attila,Gáti, Tamás,Bényei, Attila,Novák, Zoltán,Kotschy, András
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supporting information
p. 1122 - 1128
(2020/03/03)
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- Dialkylterphenyl Phosphine-Based Palladium Precatalysts for Efficient Aryl Amination of N-Nucleophiles
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A series of 2-aminobiphenyl palladacycles supported by dialkylterphenyl phosphines, PR2Ar′ (R=Me, Et, iPr, Cyp (cyclopentyl), Ar′=ArDipp2, ArXyl2f, Dipp (2,6-C6H3-(2,6-C6H3-(CHMe2)2)2), Xyl=xylyl) have been prepared and structurally characterized. Neutral palladacycles were obtained with less bulky terphenyl phosphines (i.e., Me and Et substituents) whereas the largest phosphines provided cationic palladacycles in which the phosphines adopted a bidentate hemilabile k1-P,η1-Carene coordination mode. The influence of the ligand structure on the catalytic performance of these Pd precatalysts was evaluated in aryl amination reactions. Cationic complexes bearing the phosphines PiPr2ArXyl2 and PCyp2ArXyl2 were the most active of the series. These precatalysts have demonstrated a high versatility and efficiency in the coupling of a variety of nitrogen nucleophiles, including secondary amines, alkyl amines, anilines, and indoles, with electronically deactivated and ortho-substituted aryl chlorides at low catalyst loadings (0.25–0.75 mol % Pd) and without excess ligand.
- Rama, Raquel J.,Maya, Celia,Nicasio, M. Carmen
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supporting information
p. 1064 - 1073
(2020/01/25)
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- Exhaustive Reduction of Esters Enabled by Nickel Catalysis
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We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl derivatives. This is achieved by an organosilane-mediated ester hydrosilylation reaction and subsequent Ni/NHC-catalyzed hydrogenolysis. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require the use of hazardous metal hydrides. Applications in the synthesis of -CD3-containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other C-O bonds are demonstrated.
- Cook, Adam,Prakash, Sekar,Zheng, Yan-Long,Newman, Stephen G.
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supporting information
p. 8109 - 8115
(2020/05/20)
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- Dihalogen-bridged NHC-palladium(i) dimers: Synthesis, characterisation and applications in cross-coupling reactions
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A di-iodo-bridged PdI dimer bearing an N-heterocyclic carbene ligand was made accessible via the reduction of [(IPr)PdI2]2 in basic methanol solution. The structural features of [(IPr)PdI]2 were explored by single-crystal X-ray analysis. It was found to be a convenient one-component precatalyst with high activity in Suzuki-Miyaura, Buchwald-Hartwig, and Sonogashira reactions.
- Pirkl, Nico,Del Grosso, Alessandro,Mallick, Bert,Doppiu, Angelino,Goo?en, Lukas J.
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supporting information
p. 5275 - 5278
(2019/05/08)
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- Practical Catalytic Cleavage of C(sp3)?C(sp3) Bonds in Amines
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The selective cleavage of thermodynamically stable C(sp3)?C(sp3) single bonds is rare compared to their ubiquitous formation. Herein, we describe a general methodology for such transformations using homogeneous copper-based catalysts in the presence of air. The utility of this novel methodology is demonstrated for Cα?Cβ bond scission in >70 amines with excellent functional group tolerance. This transformation establishes tertiary amines as a general synthon for amides and provides valuable possibilities for their scalable functionalization in, for example, natural products and bioactive molecules.
- Li, Wu,Liu, Weiping,Leonard, David K.,Rabeah, Jabor,Junge, Kathrin,Brückner, Angelika,Beller, Matthias
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supporting information
p. 10693 - 10697
(2019/07/09)
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- Energy Transfer to Ni-Amine Complexes in Dual Catalytic, Light-Driven C-N Cross-Coupling Reactions
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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.
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supporting information
p. 19479 - 19486
(2019/12/25)
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- Synergistic Ligand Effect between N-Heterocyclic Carbene (NHC) and Bicyclic Phosphoramidite (Briphos) Ligands in Pd-Catalyzed Amination
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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
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supporting information
p. 3253 - 3258
(2018/10/02)
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- [Pd(IPr*R)(acac)Cl]: Efficient bulky Pd-NHC catalyst for Buchwald-Hartwig C-N cross-coupling reaction
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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
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supporting information
p. 125 - 130
(2018/03/06)
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- Buchwald-Hartwig amination using Pd(i) dimer precatalysts supported by biaryl phosphine ligands
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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.
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supporting information
p. 3684 - 3688
(2018/03/21)
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- Understanding the Unusual Reduction Mechanism of Pd(II) to Pd(I): Uncovering Hidden Species and Implications in Catalytic Cross-Coupling Reactions
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The reduction of Pd(II) intermediates to Pd(0) is a key elementary step in a vast number of Pd-catalyzed processes, ranging from cross-coupling, C-H activation, to Wacker chemistry. For one of the most powerful new generation phosphine ligands, PtBu3, oxidation state Pd(I), and not Pd(0), is generated upon reduction from Pd(II). The mechanism of the reduction of Pd(II) to Pd(I) has been investigated by means of experimental and computational studies for the formation of the highly active precatalyst {Pd(μ-Br)(PtBu3)}2. The formation of dinuclear Pd(I), as opposed to the Pd(0) complex, (tBu3P)2Pd was shown to depend on the stoichiometry of Pd to phosphine ligand, the order of addition of the reagents, and, most importantly, the nature of the palladium precursor and the choice of the phosphine ligand utilized. In addition, through experiments on gram scale in palladium, mechanistically important additional Pd- and phosphine-containing species were detected. An ionic Pd(II)Br3 dimer side product was isolated, characterized, and identified as the crucial driving force in the mechanism of formation of the Pd(I) bromide dimer. The potential impact of the presence of these side species for in situ formed Pd complexes in catalysis was investigated in Buchwald-Hartwig, α-arylation, and Suzuki-Miyaura reactions. The use of preformed and isolated Pd(I) bromide dimer as a precatalyst provided superior results, in terms of catalytic activity, in comparison to catalysts generated in situ.
- Johansson Seechurn, Carin C. C.,Sperger, Theresa,Scrase, Thomas G.,Schoenebeck, Franziska,Colacot, Thomas J.
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supporting information
p. 5194 - 5200
(2017/05/04)
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- Synthesis of N-heterocyclic carbene-Pd(II) complexes and their catalytic activity in the Buchwald-Hartwig amination of aryl chlorides
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Novel N-heterocyclic carbene-palladium(II) complexes using 2-picolinic acid as the ancillary ligand have been successfully developed under mild conditions. Their catalytic activity in organic synthesis has been initially tested in the Buchwald-Hartwig amination of secondary and primary amines with aryl chlorides. Various substituents on both substrates can be tolerated, giving the desired coupling products in good to almost quantitative yields. The minimum catalyst loading can be 0.01 mol%, implying their potential application toward industrial processes.
- Zhang, Zhi-Mao,Gao, Yu-Jue,Lu, Jian-Mei
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p. 7308 - 7314
(2017/12/01)
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- N-heterocyclic carbene-palladium complex, and preparation method and application thereof
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The invention discloses an N-heterocyclic carbene-palladium complex, and a preparation method and application thereof. The N-heterocyclic carbene-palladium complex disclosed by the invention is shown in Formula (I), wherein L1 is a quinoline ligand or isoquinoline ligand, and N in the L1 is connected with Pd; L2 is an N-heterocyclic carbene ligand, and carbene carbon in the L2 is connected with the Pd; and X1 and X2 are respectively independently an anionic ligand. The N-heterocyclic carbene-palladium complex disclosed by the invention can efficiently catalyze carbon-carbon or carbon-heteroatom coupling reaction using aryl halide as a substrate. The formula is shown in the specification.
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Paragraph 0138; 0139
(2017/07/22)
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- Organonickel complexes encumbering bis-imidazolylidene carbene ligands: Synthesis, X-ray structure and catalytic insights on Buchwald-Hartwig amination reactions
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New four coordinated homoleptic bis(diimidazolylidene)nickel(II) complexes (C1 & C2) were synthesized and characterized by elemental analysis, NMR (1H and13C) as well as ESI-Mass spectrometry. The molecular structure of the complex C1 was identified by means of single-crystal X-ray diffraction analysis, which revealed that the complexes possess a distorted square planar geometry with chelating bis(diimidazolylidene) NHC ligands and two non coordinating bromide counter ions in tetradentate C4fashion. A survey of their catalytic activity in Buchwald?Hartwig amination has been performed. The newly synthesized complexes also catalyzed the amination of aryl chlorides in the presence of KOtBu. Various aryl chlorides and amines can react smoothly to give the corresponding aminated products in moderate to high yields. The scope of the reaction encompasses electronically varied aryl chlorides and nitrogen-containing heteroaryl chlorides, including pyridine and quinoline derivatives. Both secondary and primary amines are well tolerated under the optimal reaction conditions.
- Nirmala, Muthukumaran,Saranya, Gandhi,Viswanathamurthi, Periasamy,Bertani, Roberta,Sgarbossa, Paolo,Malecki, Jan Grzegorz
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supporting information
p. 1 - 10
(2017/01/09)
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- Application of a 2-aryl indenylphosphine ligand in the Buchwald-Hartwig cross-coupling reactions of aryl and heteroaryl chlorides under the solvent-free and aqueous conditions
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An efficient solvent-free protocol for the Buchwald-Hartwig cross-coupling reaction of aryl and heteroaryl chlorides with primary and secondary amines using the Pd(dba)2/ligand 1 catalytic system has been developed. Notably, the catalytic system also efficiently catalyzed the reaction under aqueous conditions.
- Liu, Yan,Yuan, Jia,Wang, Zi-Fei,Zeng, Si-Hao,Gao, Meng-Yue,Ruan, Mei-Lin,Chen, Jian,Yu, Guang-Ao
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supporting information
p. 5805 - 5810
(2017/07/22)
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- The synthesis of planar chiral pseudo-gem aminophosphine pre-ligands based on [2.2]paracyclophane
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The synthesis of three planar chiral pseudo-gem disubstituted [2.2]paracyclophane-derived P,N-pre-ligands is reported along with preliminary results of their activity in the amination of aryl bromides and chlorides. The pseudo-gem aminophosphines were capable of mediating the coupling reaction at a loading of 1 mol%.
- Jayasundera, Krishanthi P.,Engels, Tim G. W.,Lun, David J.,Mungalpara, Maulik N.,Plieger, Paul G.,Rowlands, Gareth J.
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p. 8975 - 8984
(2017/11/09)
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- Solvent-Free Buchwald-Hartwig (Hetero)arylation of Anilines, Diarylamines, and Dialkylamines Mediated by Expanded-Ring N-Heterocyclic Carbene Palladium Complexes
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A highly efficient solvent-free protocol for the Buchwald-Hartwig (hetero)arylation of anilines, diarylamines, and dialkylamines mediated by the expanded-ring N-heterocyclic carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp = 1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene; cinn = cinnamyl, 3-phenylallyl] was developed. The catalytic protocol was efficient for the coupling of amines and (hetero)aryl chlorides and bromides bearing donor, acceptor, and bulky substituents.
- Topchiy, Maxim A.,Dzhevakov, Pavel B.,Rubina, Margarita S.,Morozov, Oleg S.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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supporting information
p. 1908 - 1914
(2016/04/20)
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- An easily available N-heterocyclic carbene–palladium(II) catalyst for Buchwald–Hartwig amination of aryl chlorides
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Abstract: An easily available N-heterocyclic carbene–palladium(II) complex was found to be an efficient catalyst for the Buchwald–Hartwig amination of aryl chlorides. Both secondary and primary amines were tolerated under the same reaction conditions. Under the optimal conditions, all reactions proceeded successfully to give the desired products in good to high yields within hours. Graphical Abstract: [Figure not available: see fulltext.]
- Wang, Tao,Xu, Kai,Liu, Lantao,Xie, Huanping,Li, Ying,Zhao, Wen-Xian
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p. 525 - 529
(2016/07/20)
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- Synthesis and characterization of N-heterocyclic carbene-palladium(II) chlorides-1-methylindazole and -1-methylpyrazole complexes and their catalytic activity toward C-N coupling of aryl chlorides
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A series of N-heterocyclic carbene-palladium(ii) chlorides-1-methylindazole and -1-methylpyrazole complexes was successfully synthesized and fully characterized by X-ray single crystal diffraction. In addition, initial investigations of their catalytic activity showed that they were efficient catalysts in the C-N coupling of primary and secondary amines with aryl chlorides at low catalyst loadings.
- Zhao, Xiao-Yun,Zhou, Quan,Lu, Jian-Mei
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p. 24484 - 24490
(2016/03/15)
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- Synthesis of N-heterocyclic carbene-PdCl2-(iso)quinoline complexes and their application in arylamination at low catalyst loadings
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A new type of N-heterocyclic carbene-PdCl2-(iso)quinoline complexes 3 were successfully achieved in acceptable to good yields from easily available starting materials under mild conditions, and their structures were unambiguously confirmed using X-ray single crystal diffraction. Furthermore, their catalytic activity toward Buchwald-Hartwig arylamination of aryl chlorides with primary and secondary amines was fully tested. Under the optimal reaction conditions, the expected arylated amines can be obtained in high to excellent yields at low catalyst loadings (0.005-0.05 mol%). It may be worth noting here that comparison of these complexes with other well-defined and easily available NHC-Pd(ii) complexes bearing different N-containing ancillary ligands was also carried out, showing their superior catalytic activity over all others.
- Liu, Feng,Zhu, Yi-Ran,Song, Lu-Gan,Lu, Jian-Mei
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p. 2563 - 2571
(2016/03/01)
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- A Bis(silylene)-Substituted ortho-Carborane as a Superior Ligand in the Nickel-Catalyzed Amination of Arenes
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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
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supporting information
p. 12868 - 12872
(2016/10/04)
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- Preparation method of novel bidentate phosphite ligand and application thereof in Buchwald-Hartwig reaction
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The invention discloses a preparation method of novel bidentate phosphite ligands and application thereof in Buchwald-Hartwig reaction and belongs to the field of organic synthetic chemistry. A series of novel bidentate phosphite ligands are synthesized by using 3,3',5,5'-tetra-tert-butyl-2,2'-dihydroxyl diphenyl and glycols with different structures as raw materials through a two-step one-pot method, are compounds very wide in application range and have the following structures. The novel preparation method has the advantages of being stable in structure, simple and convenient to synthesize, high in yield and easy to prepare in a large-scale mode. The ligands have higher reaction activity and substrate universality in the Pd catalyzed Buchwald-Hartwig reaction.
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Paragraph 0050; 0051; 0052; 0053; 0054; 0057; 0058; 0060-64
(2016/10/09)
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- Efficient and versatile buchwald-hartwig amination of (hetero)aryl chlorides using the Pd-PEPPSI-IPr(NMe2)2 precatalyst in the presence of carbonate base
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The precatalyst Pd-PEPPSI-IPr(NMe2)2, in which the IPr ligand was modified by attachment of two dimethylamino groups on to the 4- and 5-positions of the imidazolyl heterocycle, was found to show high catalytic efficiency in the Buchwald-Hartwig amination under mild conditions using Cs2CO3 as a weak base, using a low catalyst loading of 1 mol-%. The protocol is applicable to aryl chlorides bearing base-sensitive substituents, as exemplified by the coupling of 4-chloroacetophenone with aniline. It can also be used with an unprecedentedly wide range of amines, including strongly basic secondary alkylamines, primary arylamines, and primary alkylamines. The Palladium precatalyst Pd-PEPPSI-IPr(NMe2)2, whose supporting N-heterocyclic carbene ligand was decorated with two dimethylamino groups, was found to catalyse the Buchwald-Hartwig amination of aryl halides with a wide range of amines under mild conditions using cesium carbonate as base.
- Zhang, Yin,César, Vincent,Lavigne, Guy
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p. 2042 - 2050
(2015/03/18)
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- Copper-catalyzed C-N bond cross-coupling of aryl halides and amines in water in the presence of ligand derived from oxalyl dihydrazide: Scope and limitation
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An efficient and convenient method has been developed for the copper-catalyzed C-N bond cross-coupling of aryl bromides with electron-donor substituents and aliphatic amines in water. The new ligand system N-phenyloxalyl bishydrazide/hexane-2,5-dione has been shown to be considerably more efficient in the copper-catalyzed C-N bond cross-coupling reaction as compared to the ligands described in the literature and allowed decreasing of the catalyst amount (up to 2 mol %) to achieve acceptable yields of isolated products (46-84%). Acceptor substituted aryl bromides, aryl bromides with substituents in the ortho-position, and some aryl dichlorides can undergo the C-N cross-coupling under the developed conditions, but their reactivity is lower.
- Kurandina,Eliseenkov,Khaibulova,Petrov,Boyarskiy
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p. 7931 - 7937
(2015/09/15)
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- Copper-Catalyzed Electrophilic Amination of Organoaluminum Nucleophiles with O -Benzoyl Hydroxylamines
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A copper-catalyzed electrophilic amination of aryl and heteroaryl aluminums with N,N-dialkyl-O-benzoyl hydroxylamines that affords the corresponding anilines in good yields has been developed. The catalytic reaction proceeds very smoothly under mild conditions and exhibits good substrate scope. Moreover, the developed catalytic system is also well suited for heteroaryl aluminum nucleophiles, providing facile access to heteroaryl amines.
- Zhou, Shuangliu,Yang, Zhiyong,Chen, Xu,Li, Yimei,Zhang, Lijun,Fang, Hong,Wang, Wei,Zhu, Xiancui,Wang, Shaowu
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p. 6323 - 6328
(2015/06/30)
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- Palladium-catalyzed amination of aryl sulfides with aliphatic amines
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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
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supporting information
p. 2678 - 2682
(2015/04/27)
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- Ligand-free C-C and C-N cross-couplings with Pd/Nf-G nanocomposite
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Abstract The catalytic activity of electrochemical deposited Pd nanoparticles on nafion-graphene support was examined for Buchwald-Hartwig amination reaction and Heck coupling reaction. The developed protocol is very efficient and ecofriendly, providing excellent product yield. The Pd/Nf-G catalyst can be used up to four cycles with slight decrease in catalytic activity.
- Shelkar, Radheshyam S.,Shendage, Suresh S.,Nagarkar, Jayashree M.
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supporting information
p. 4463 - 4467
(2015/06/30)
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- Modular synthesis of functionalisable alkoxy-tethered N-heterocyclic carbene ligands and an active catalyst for buchwald-hartwig aminations
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Modular syntheses of functionalised, alkoxy-tethered 1,3-bis(2,4,6- trimethylphenyl)imidazolium (IMes*H+) and 1,3-bis(2,6- diisopropylphen-l)imidazolium (IPr*H+) derivatives 1,3-bis(4-alkyl- -2,4,6-trimethylphenyl)imidazolium (IXyOR*H+) and 1,3-bis(4-alkyl-oxy-2,6-diisopropylphenyl)imidazolium (IPrOR*H +) are reported. A reliable synthesis of the key starting material 4-amino-3,5-diisopropylphenol is also described. Etherification of hydroxydecorated ligand intermediates before formation of the imidazolium core and subsequent modification, or direct etherification of the versatile synthon IPrOH·HCl, allowed access to various linker types including triethoxysilyl, primary amino and norbornenyl, which are not accessible by other methods. An IPrOR-palladium(II) complex was prepared, and its catalytic activity was evaluated in challenging Buchwald- Hartwig aminations of aryl chlorides. This precatalyst displayed excellent activity and selectivity under mild reaction conditions, achieving in some cases a 10-fold improvement in TOF relative to the IPr-based version. An unexpected activity profile was observed wherein sterically demanding anilines were coupled more easily than those lacking orthosubstitution.
- Krinsky, Jamin L.,Martinez, Alberto,Godard, Cyril,Castillon, Sergio,Claver, Carmen
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supporting information
p. 460 - 474
(2014/05/20)
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- N-heterocyclic carbene-palladium(II)-4,5-dihydrooxazole complexes: Synthesis and catalytic activity toward amination of aryl chlorides
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A series of novel N-heterocyclic carbene-palladium(II)-4,5-dihydrooxazole (NHC-PdII-Ox) complexes 3 were successfully synthesized from commercially available imidazolium salts 1, PdCl2, and 4,5-dihydrooxazoles 2 in a one-step process, and these complexes showed efficient catalytic activity toward the amination of aryl chlorides. Both secondary and primary amines were tolerated under the same reaction conditions. Under the optimal reaction conditions, the expected coupling products were obtained in moderate to high yields.
- Huang, Pei,Wang, Yi-Xiang,Yu, Hong-Fei,Lu, Jian-Mei
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supporting information
p. 1587 - 1593
(2014/05/06)
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- Solvent-free Buchwald-Hartwig reaction of aryl and heteroaryl halides with secondary amines
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A highly efficient solvent-free protocol for the Buchwald-Hartwig amination of (hetero)aryl halides by secondary amines was developed. The reaction is mediated by a Pd(OAc)2/RuPhos catalytic system in air. Various (hetero)aryl halides were coupled with diaryl, alkyl-aryl, and dialkylamines in good to excellent yields (51 examples, 50-99% yield). Copyright
- Topchiy, Maxim A.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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p. 3319 - 3322
(2014/06/09)
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- Efficient C-N and C-S bond formation using the highly active [Ni(allyl)Cl(IPr*OMe)] precatalyst
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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.
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supporting information
p. 3127 - 3131
(2014/06/09)
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- Nickel-catalyzed amination of aryl chlorides and sulfamates in 2-methyl-THF
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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.
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p. 3289 - 3293
(2015/02/19)
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- Palladium-catalysed amination of aryl- and heteroaryl halides using tert-butyl tetraisopropylphosphorodiamidite as an easily accessible and air-stable ligand
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The phosphorus compound tert-butyl tetraisopropylphosphorodiamidite, prepared from bis(diisopropylamino)chlorophosphine, is an excellent ligand for palladium-catalysed Buchwald-Hartwig amination of aryl- and heteroaryl chlorides and bromides. Based on its ready accessibility and air-stability, this amination protocol is a practical approach to the synthesis of industrially important aryl- and heteroarylamines. Copyright
- Roiban, Gheorghe-Doru,Mehler, Gerlinde,Reetz, Manfred T.
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p. 2070 - 2076
(2014/04/17)
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- The facet-dependent enhanced catalytic activity of Pd nanocrystals
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A systematic study of heterogeneous Buchwald-Hartwig amination using shape-controlled Pd nanocrystals with distinctly different surface facets is presented. This journal is the Partner Organisations 2014.
- Kim, Minjune,Kim, Yeonjoon,Hong, Jong Wook,Ahn, Seihwan,Kim, Woo Youn,Han, Sang Woo
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supporting information
p. 9454 - 9457
(2014/08/18)
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- Coupling of boronic acids with amines in the presence of a supported copper catalyst
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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
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p. 1547 - 1551,5
(2014/11/12)
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- Nickel-catalyzed cross-coupling of aryltrimethylammonium triflates and amines
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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
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p. 1448 - 1453
(2014/03/21)
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- Nano Pd-Fe3O4@Alg beads: As an efficient and magnetically separable catalyst for Suzuki, Heck and Buchwald-Hartwig coupling reactions
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Catalytic processes are the backbone of many chemical industries. In a comparative study of various heterogeneous catalytic systems, we report efficient and magnetically separable nano Pd-Fe3O4@Alg beads as catalysts for Suzuki, Heck and Buchwald-Hartwig coupling reactions. This catalyst was characterized by SEM, TEM, HRTEM, XRD, EDAX, FT-IR, VSM, DSC-TGA, BET, and UV-Visible spectroscopy. This heterogeneous catalyst showed high catalytic activity and stability for C-C and C-N bond forming coupling reactions with excellent product yield under ligand free conditions. The beads of nano Pd-Fe3O4@Alg can be separated from the reaction mixture by an external magnet and reused for several successive cycles with no appreciable loss in the catalytic activity. The Suzuki and Heck coupling reactions in aqueous medium are greener routes, which is an added advantage of this protocol. This journal is
- Shelkar, Radheshyam S.,Gund, Sitaram H.,Nagarkar, Jayashree M.
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p. 53387 - 53396
(2015/02/05)
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- Troeger's base derived phosphanes for Suzuki-Miyaura and Buchwald-Hartwig cross-coupling reactions
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A library of bis(phosphane) ligands based on the 2,8-substituted Troeger's base scaffold was synthesized through an efficient two-step protocol by starting from a commercially available aniline. The new ligands proved their efficiency in palladium-catalyzed Suzuki-Miyaura cross-coupling reactions and Buchwald-Hartwig aminations of aryl chlorides and bromides. Copyright
- Pereira, Raul,Cvengros, Jan
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supporting information
p. 4233 - 4237
(2013/07/26)
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- New phosphine-functionalized NHC ligands: Discovery of an effective catalyst for the room-temperature amination of aryl chlorides with primary and secondary amines
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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
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p. 6148 - 6161
(2013/12/04)
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- Novel robust benzimidazolylidene palladium complexes: Synthesis, structure, and catalytic applications in amination of chloroarenes
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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
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p. 673 - 679
(2013/07/27)
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- N-Heterocyclic carbene adducts of cyclopalladated ferrocenylpyridine: Synthesis, structural characterization and reusable catalytic system for Suzuki and amination of aryl chlorides in poly(ethylene glycol-400)
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Two air-stable carbene adducts of cyclopalladated ferrocenylpyridine 1-2 have been synthesized and characterized by elemental analysis, IR, ESI-MS, 1H and 13C NMR. Additionally, their detailed structures have been determined by singl
- Xu, Chen,Li, Hong-Mei,Liu, Hu,Zhang, Zhi-Qiang,Wang, Zhi-Qiang,Fu, Wei-Jun,Zhang, Yu-Qing
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experimental part
p. 22 - 26
(2012/06/15)
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- Buchwald-Hartwig amination of (hetero)aryl chlorides by employing Mor-DalPhos under aqueous and solvent-free conditions
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We report on the application of the [Pd(cinnamyl)Cl]2/Mor- DalPhos catalyst system in the Buchwald-Hartwig amination of (hetero)aryl chlorides with primary or secondary amines conducted either under aqueous conditions without the use of co-solvents and/or surfactants or under solvent-free conditions (52 examples). We have established that reactions of this type can be conducted without the rigorous exclusion of air, and in the case of the solvent-free reactions, we have demonstrated that appropriately selected liquid and solid reagents can be employed successfully.
- Tardiff, Bennett J.,Stradiotto, Mark
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supporting information; experimental part
p. 3972 - 3977
(2012/08/27)
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- Air-stable and highly efficient indenyl-derived phosphine ligand: Application to Buchwald-Hartwig amination reactions
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2-Mesitylindenyl phosphine ligand (1) and [(2-mesitylindenyl)dicyclohexyl- phosphine]PdCl2 (2) have been synthesized and fully characterized by NMR and elemental analysis, as well as by X-ray crystallography for 2. A Highly active catalyst system derived from a palladium precatalyst and bulky 2-mesitylindenyl phosphine ligand (1) for the Buchwald-Hartwig amination reaction of aryl halides with primary and secondary amines has been developed. This method allows for the preparation of a wide variety of amines in moderate to excellent yields and displays a high level of activity for the coupling of aryl chlorides as well as hindered aryl bromides.
- Hao, Xiaowei,Yuan, Jia,Yu, Guang-Ao,Qiu, Ming-Qiang,She, Neng-Fang,Sun, Yue,Zhao, Cui,Mao, Shu-Lan,Yin, Jun,Liu, Sheng-Hua
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experimental part
p. 99 - 105
(2012/06/17)
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