- Evidence for "cocktail"-type catalysis in Buchwald-Hartwig reaction. A mechanistic study
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The mechanism of the C-N cross-coupling reaction, catalyzed by palladium complexes with N-heterocyclic carbene ligands (Pd/NHC), was evaluated in detail at the molecular and nanoscale levels. For the first time, the formation of a "cocktail"-type catalytic system was proven for the Buchwald-Hartwig reaction. The unique ability of the Pd/NHC system to generate several types of catalytic centers (Pd complexes, clusters and nanoparticles) and the involvement of complementary pathways (homogeneous and heterogeneous) were discovered to take place in a "one pot"manner directly in the reaction vessel. Access to various catalytic centers from a single and readily available Pd/NHC complex is the key to designing a universal catalytic system with adaptive tuning capability. This journal is
- Ananikov, Valentine P.,Boiko, Daniil A.,Burykina, Julia V.,Madiyeva, Malena,Minyaev, Mikhail E.,Prima, Darya O.
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p. 7171 - 7188
(2021/11/17)
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- Commercial Pd/C-Catalyzed N-Methylation of Nitroarenes and Amines Using Methanol as Both C1 and H2 Source
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Herein, we report commercially available carbon-supported-palladium (Pd/C)-catalyzed N-methylation of nitroarenes and amines using MeOH as both a C1 and a H2 source. This transformation proceeds with high atom-economy and in an environmentally friendly way via borrowing hydrogen mechanism. A total of >30 structurally diverse N-methylamines, including bioactive compounds, were selectively synthesized with isolated yields of up to 95%. Furthermore, selective N-methylation and deuteration of nimesulide, a nonsteroidal anti-inflammatory drug, were realized through the late-stage functionalization.
- Goyal, Vishakha,Gahtori, Jyoti,Narani, Anand,Gupta, Piyush,Bordoloi, Ankur,Natte, Kishore
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p. 15389 - 15398
(2019/12/04)
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- Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines
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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
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supporting information
p. 7261 - 7265
(2019/05/16)
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- Nickel(II) complex incorporating methylene bridged tetradentate dicarbene ligand as an efficient catalyst toward CC and CN bond formation reactions
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For the evaluation of binding and catalytic nature of N-heterocyclic carbenes (NHCs) and their complexes, a new methylene bridged bis(aryloxy-NHC) ligand has been prepared. A novel air-stable Ni(II) complex bearing the new NHC ligand has been synthesized and characterized by elemental analysis, NMR (1H and 13C) as well as ESI-mass spectrometry. The molecular structure of the complex was identified by means of single crystal X-ray diffraction analysis which revealed that the Ni(II) complex possesses a square planar geometry with the ligand coordinating with bi-negative tetradentate C2O2 fashion and the complex showed efficient catalytic activity toward the Suzuki-Miyaura cross-coupling reaction between aryl halides and arylboronic acids under phosphine free conditions. The new complex 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. Both secondary and primary amines are well tolerated under the optimal reaction conditions.
- Nirmala, Muthukumaran,Prakash, Govindan,Ramachandran, Rangasamy,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Linert, Wolfgang
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- Skeleton decoration of NHCs by amino groups and its sequential booster effect on the palladium-catalyzed Buchwald-Hartwig amination
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A challenging synthetic modification of PEPPSI-type palladium pre-catalysts consisting of a stepwise incorporation of one and two amino groups onto the NHC skeleton was seen to exert a sequential enhancement of the electronic donor properties. This appears to be positively correlated with the catalytic performances of the corresponding complexes in the Buchwald-Hartwig amination. This is illustrated, for example, by the quantitative amination of 4-chloroanisole by morpholine within 2 h at 25°C with a 2 mol% catalyst/substrate ratio or by a significant reduction of catalytic loading (down to 0.005 mol%) for the coupling of aryl chlorides with anilines (max TON: 19600).
- Zhang, Yin,Cesar, Vincent,Storch, Golo,Lugan, Noel,Lavigne, Guy
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supporting information
p. 6482 - 6486
(2014/06/24)
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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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- Facile catalytic SNAr reaction of nonactivated fluoroarenes with amines using η6-benzene ruthenium(II) complex
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Catalytic SNAr reaction of fluoroarenes possessing no electron-withdrawing group(s) with cyclic amines was achieved using a readily accessible Ru catalyst, which was prepared from [Ru(benzene)Cl2] 2, AgOTf, and P(p-FC6H4)3. The coexistence of molecular sieves MS4A realized high conversion and various substituted aryl amines were obtained in good to high yields. Georg Thieme Verlag Stuttgart New York.
- Otsuka, Maiko,Yokoyama, Hiroya,Endo, Kohei,Shibata, Takanori
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scheme or table
p. 2601 - 2606
(2010/11/19)
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- Catalytic SNAr reaction of non-activated fluoroarenes with amines via Ru η6-arene complexes
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Ru-catalyzed SNAr reaction of non-activated fluoroarenes with secondary amines proceeded through η6-arene complexes to give aminated products in up to 79% yield.
- Otsuka, Maiko,Endo, Kohei,Shibata, Takanori
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supporting information; experimental part
p. 336 - 338
(2010/05/01)
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- Neopentylphosphines as effective ligands in palladium-catalyzed cross-couplings of aryl bromides and chlorides
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The use of neopentylphosphine ligands in the palladium-catalyzed Suzuki, Sonogashira, Heck, and Hartwig-Buchwald couplings of aryl bromides and chlorides are reported. Di-tert-butylneopentylphosphine (DTBNpP) provided highly active catalysts for the coupling of aryl bromides at mild temperatures. Trineopentylphosphine, an air-stable trialkylphosphine, gave inactive catalysts at room temperature, but showed good activity in the H-B amination of aryl chlorides at elevated temperatures.
- Hill, Lensey L.,Smith, Joanna M.,Brown, William S.,Moore, Lucas R.,Guevera, Paul,Pair, Emily S.,Porter, Jake,Chou, Joe,Wolterman, Christopher J.,Craciun, Raluca,Dixon, David A.,Shaughnessy, Kevin H.
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p. 6920 - 6934
(2008/09/21)
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- Bulky alkylphosphines with neopentyl substituents as ligands in the amination of aryl bromides and chlorides
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Di(tert-butyl)neopentylphosphine (DTBNpP) in combination with palladium sources provided catalysts with comparable or better activity for the Hartwig-Buchwald amination of aryl bromides than tri(tert-butyl)phosphine (TTBP) under mild conditions. DTBNpP also provided effective catalysts for amination reactions of aryl chlorides at elevated temperatures. Further replacement of tert-butyl groups with neopentyl substituents resulted in less effective ligands for amination reactions. Computationally derived cone angles showed that replacement of a tert-butyl group with a neopentyl group significantly increased the cone angle of the phosphine. The larger cone angle of DTBNpP than TTBP appears to correlate with the higher activity of catalysts derived from DTBNpP in the amination of aryl bromides. TTBP is a stronger electron donor than DTBNpP, which may explain the higher activity for TTBP-derived catalysts toward aryl chlorides.
- Hill, Lensey L.,Moore, Lucas R.,Huang, Rongeai,Craciun, Raluca,Vincent, Andrew J.,Dixon, David A.,Chou, Joe,Woltermann, Christopher J.,Shaughnessy, Kevin H.
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p. 5117 - 5125
(2007/10/03)
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- Phospha-adamantanes as ligands for organopalladium chemistry: Aminations of aryl halides
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The use of Pd2dba3·CHCl3 and 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phospha-adamantane has been shown to facilitate the effective amination of aryl halides with aromatic or aliphatic amines in high yields.
- Gerristma, David,Brenstrum, Timothy,McNulty, James,Capretta, Alfredo
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p. 8319 - 8321
(2007/10/03)
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- Rapid and Efficient Microwave-Assisted Amination of Electron-Rich Aryl Halides without a Transition-Metal Catalyst
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Equation presented. A rapid and direct amination of aryl halides has been developed in good to high yields under microwave irradiation without a transition-metal catalyst. This reaction is a particularly powerful method for the coupling of electron-rich aryl halides with various amines. In some cases, the excellent regioselectivity could be observed, which facilitated the preparation of meta-substituted anilines from ortho- or para-substituted phenylhalides. In addition, a mechanism via the interesting benzyne intermediate has been proposed.
- Shi, Lei,Wang, Min,Fan, Chun-An,Zhang, Fu-Min,Tu, Yong-Qiang
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p. 3515 - 3517
(2007/10/03)
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- Preparation and properties of N,N,N′,N′-tetrasubstituted 1,4-benzenediamines
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The synthesis of nine different N,N,N′,N′-tetrasubstituted 1,4-benzenediamines is described. These compounds are of interest as mediators for glucose oxidase based biosensors and as donor molecules for conducting molecular solids. The electrochemical behaviour and the electronic absorption spectra have been investigated. Acta Chemica Scandinavica 1996.
- Christensen, Jorn B.,Schiodt, Niels-Christian,Bechgaard, Klaus,Buch-Rasmussen, Thomas
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p. 1013 - 1019
(2007/10/03)
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