- Accessing Tricyclic Imines Comprising a 2-Azabicyclo[22.2]octane Scaffold by Intramolecular Hetero-Diels-Alder Reaction of 4-Alkenyl-Substituted N-Silyl-1,4-dihydropyridines
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Tricyclic imines inheriting a 2-Azabicyclo[2.2.2]octane (isoquinuclidine) scaffold were provided with high regioselectivity in moderate to very good yields by a smooth, broadly applicable intramolecular hetero-Diels-Alder reaction of various 4-ω-Alkenyl-substituted 1,4-dihydropyridines (DHPs) under trifluoroacetic acid catalysis. The required? 4,4-disubstituted 1,4-DHPs were obtained by introduction of ω-Alkenyl moieties of varying chain length via diorganomagnesium reagents into the 4-position of diversely 4-substituted pyridines after prior N-Activation with triisopropylsilyltriflate.
- Rudy, Heinrich-Karl A.,Wanner, Klaus T.
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- Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
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A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
- Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
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p. 208 - 218
(2021/12/29)
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- Decarbonylative Pd-Catalyzed Suzuki Cross-Coupling for the Synthesis of Structurally Diverse Heterobiaryls
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Heteroaromatic biaryls are core scaffolds found in a plethora of pharmaceuticals; however, their direct synthesis by the Suzuki cross-coupling is limited to heteroaromatic halide starting materials. Here, we report a direct synthesis of diverse nitrogen-containing heteroaromatic biaryls by Pd-catalyzed decarbonylative Suzuki cross-coupling of widely available heterocyclic carboxylic acids with arylboronic acids. The practical and modular nature of this cross-coupling enabled the straightforward preparation of >45 heterobiaryl products using pyridines, pyrimidines, pyrazines, and quinolines in excellent yields. We anticipate that the modular nature of this protocol will find broad application in medicinal chemistry and drug discovery research.
- Blakemore, David C.,Cervantes-Reyes, Alejandro,Chinigo, Gary M.,Smith, Aaron C.,Szostak, Michal
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supporting information
p. 1678 - 1683
(2022/03/14)
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- Cobalt-catalyzed cross-coupling of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium reagents
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Cobalt-catalyzed cross-couplings of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium halides proceeded efficiently with the aid of cobalt(II) catalyst and copper(I) salt in tetrahydrofuran at ambient temperature, producing the desired
- Cui, Yan-Ying,Na, Jin-He,Guo, Meng-Meng,Huang, Jie-Ying,Chu, Xue-Qiang,Rao, Weidong,Shen, Zhi-Liang
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supporting information
(2022/02/16)
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- Magnetic chitosan-functionalized cobalt-NHC: Synthesis, characterization and catalytic activity toward Suzuki and Sonogashira cross-coupling reactions of aryl chlorides
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Aryl chlorides are one of the most stable and available electrophiles, however, their coupling with nucleophiles remains a challenge in organic synthesis. Herein, we prepared a Cobalt-NHC (N-Heterocyclic carbene) complex anchored on magnetic chitosan nanoparticles and assayed its catalytic activity for the reactions of substituted phenylboronic acid and also phenlacetylene with derivatives of aryl chlorides. These reactions are of great importance since they are employed for the synthesis of unsymmetrical diarylethynes and biphenyls, which belong to a prime class of building blocks. The synthesized nanocatalyst was found to be highly efficient in Suzuki and Sonogashira coupling in terms of their activity and recyclability in polyethylene glycol (PEG) as a green reaction media under conditions of temperatures (70 and 100 °C) and Co loading (3 and 6 mol%). To the best of our knowledge, this is the first attempt of using cobalt-NHC complex for catalyzing the abovementioned reactions. Moreover, replacing the earth-abundant Cobalt-based catalyst as an alternative to high cost palladium make this approach promising from sustainable chemistry view.
- Hajipour, Abdol R.,Malek, Shaghayegh Sadeghi
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- Practical and Regioselective Synthesis of C-4-Alkylated Pyridines
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The direct position-selective C-4 alkylation of pyridines has been a long-standing challenge in heterocyclic chemistry, particularly from pyridine itself. Historically this has been addressed using prefunctionalized materials to avoid overalkylation and mixtures of regioisomers. This study reports the invention of a simple maleate-derived blocking group for pyridines that enables exquisite control for Minisci-type decarboxylative alkylation at C-4 that allows for inexpensive access to these valuable building blocks. The method is employed on a variety of different pyridines and carboxylic acid alkyl donors, is operationally simple and scalable, and is applied to access known structures in a rapid and inexpensive fashion. Finally, this work points to an interesting strategic departure for the use of Minisci chemistry at the earliest possible stage (native pyridine) rather than current dogma that almost exclusively employs Minisci chemistry as a late-stage functionalization technique.
- Baran, Phil S.,Choi, Jin,Godineau, Edouard,Laudadio, Gabriele
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p. 11927 - 11933
(2021/08/20)
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- Base-Activated Latent Heteroaromatic Sulfinates as Nucleophilic Coupling Partners in Palladium-Catalyzed Cross-Coupling Reactions
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Heteroaromatic sulfinates are effective nucleophilic reagents in Pd0-catalyzed cross-coupling reactions with aryl halides. However, metal sulfinate salts can be challenging to purify, solubilize in reaction media, and are not tolerant to multi-step transformations. Here we introduce base-activated, latent sulfinate reagents: β-nitrile and β-ester sulfones. We show that under the cross-coupling conditions, these species generate the sulfinate salt in situ, which then undergo efficient palladium-catalyzed desulfinative cross-coupling with (hetero)aryl bromides to deliver a broad range of biaryls. These latent sulfinate reagents have proven to be stable through multi-step substrate elaboration, and amenable to scale-up.
- Blakemore, David C.,Cook, Xinlan A. F.,Moses, Ian B.,Pantaine, Lo?c R. E.,Sach, Neal W.,Shavnya, Andre,Willis, Michael C.
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p. 22461 - 22468
(2021/09/09)
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- Sequential Ring-Opening and Ring-Closing Reactions for Converting para-Substituted Pyridines into meta-Substituted Anilines
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Herein we report a method for converting para-substituted pyridine rings into meta-dialkylamino-substituted benzene rings through sequential ring-opening and ring-closing reactions. The nitrogen atom in the pyridine rings was replaced with a methine group, and a dialkylamino substituent was introduced onto the original unsubstituted carbon atom in the pyridine rings. This process can be formally regarded as a hybrid of the skeletal editing and C-H amination of pyridine rings.
- Morofuji, Tatsuya,Inagawa, Kota,Kano, Naokazu
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supporting information
p. 6126 - 6130
(2021/08/18)
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- Synthesis of Arylpalladium(II) Boronates: Confirming the Structure and Chemical Competence of Pre-transmetalation Intermediates in the Suzuki–Miyaura Reaction
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Palladium(II) boronates are recognized as fundamental pre-transmetalation intermediates in Suzuki–Miyaura cross-couplings. While these typically transient species have been detected and studied spectroscopically, it is conspicuous that they have never been isolated since this important reaction was discovered over forty years ago. This study reports the synthesis of a family of unprecedented arylpalladium(II) boronates that are, by design, kinetically stable at ambient temperature, both in solution and in the solid state. These properties enabled unambiguous crystallographic confirmation of their structure for the first time and their chemical competence in a Suzuki–Miyaura reaction was demonstrated.
- Bissember, Alex C.,Canty, Allan J.,Ho, Curtis C.,Horne, James,Lucas, Nigel T.,Olding, Angus
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supporting information
p. 14897 - 14901
(2021/05/31)
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- Quantifying Through-Space Substituent Effects
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The description of substituents as electron donating or withdrawing leads to a perceived dominance of through-bond influences. The situation is compounded by the challenge of separating through-bond and through-space contributions. Here, we probe the experimental significance of through-space substituent effects in molecular interactions and reaction kinetics. Conformational equilibrium constants were transposed onto the Hammett substituent constant scale revealing dominant through-space substituent effects that cannot be described in classic terms. For example, NO2 groups positioned over a biaryl bond exhibited similar influences as resonant electron donors. Meanwhile, the electro-enhancing influence of OMe/OH groups could be switched off or inverted by conformational twisting. 267 conformational equilibrium constants measured across eleven solvents were found to be better predictors of reaction kinetics than calculated electrostatic potentials, suggesting utility in other contexts and for benchmarking theoretical solvation models.
- Adam, Catherine,Burns, Rebecca J.,Cockroft, Scott L.,Mati, Ioulia K.,Muchowska, Kamila B.
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supporting information
p. 16717 - 16724
(2020/07/24)
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- Palladium-Catalyzed Electrophilic Functionalization of Pyridine Derivatives through Phosphonium Salts
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Herein, we report a highly efficient and practical method for pyridine-derived heterobiaryl synthesis through palladium-catalyzed electrophilic functionalization of easily available pyridine-derived quaternary phosphonium salts. The nice generality of this reaction was goes beyond arylation, enabling facile incorporation of diverse carbon-based fragments, including alkenyl, alkynyl, and also allyl fragments, onto the pyridine core. Notably, the silver salt additive is revealed to be of vital importance for the success of this transformation and its pivotal role as transmetallation mediator, which guarantees a smooth transfer of pyridyl group to palladium intermediate, is also described.
- Che, Yuan-Yuan,Deng, Xuezu,Feng, Chao,Lin, Ling-Zhi,Pei, Bingbing,Yue, Yanni
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supporting information
p. 16414 - 16419
(2020/07/20)
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- Pyridine derivative compound and preparation method thereof
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The invention discloses a pyridine derivative compound and a preparation method thereof. The preparation method comprises the steps: in an inert gas atmosphere, sequentially adding heterocyclic quaternary phosphonium salt, iodide, alkali, a silver additive, a palladium catalyst and a phosphorus ligand into a solvent, to obtain a mixture, wherein the molar ratio of the heterocyclic quaternary phosphonium salt to the iodide to the alkali to the silver additive to the palladium catalyst to the phosphorus ligand is (2.5-25):(1-10):(3-30):(1.2-12):(0.5-5):(1-10), and the molar volume ratio of the iodide to the solvent is 0.1 mmol:1 mL; and then, in an inert gas atmosphere, carrying out reaction on the mixture at the temperature of 62-68 DEG C for 11-13 h, and collecting a reaction product, namely the pyridine derivative compound. According to the preparation method, the adopted raw materials are simple and easy to obtain, the substrate range is wide, the cost is low, the reaction conditionsare mild, and the catalyst dosage is extremely small.
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Paragraph 0030-0032; 0061-0066
(2020/08/17)
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- Synthesis of 2-Arylpyridines and 2-Arylbipyridines via Photoredox-Induced Meerwein Arylation with in Situ Diazotization of Anilines
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We report herein a sustainable method for the preparation of 2-arylpyridines through C-H arylation of pyridines using in situ formed diazonium salts (from commercially available aromatic amines) in the presence of a photoredox catalyst under blue light-emitting diode (LED) irradiation. The reaction is tolerant to a wide range of functional groups (e.g., halogen, nitrile, formyl, acetyl, ester). Applications to the C-H bond arylation of bipyridine ligands is also presented.
- Hagui, Wided,Soulé, Jean-Fran?ois
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p. 3655 - 3663
(2020/03/04)
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- Photoarylation of Pyridines Using Aryldiazonium Salts and Visible Light: An EDA Approach
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A metal-free methodology for the photoarylation of pyridines, in water, is described giving 2 and 4-arylated-pyridines in yields up to 96percent. The scope of the aryldiazonium salts is presented showing important results depending on the nature and position of the substituent group in the diazonium salt, that is, electron-donating or electron-withdrawing in the ortho, meta, or para positions. Further heteroaromatics were also successfully photoarylated. Mechanistic studies and comparison between our methodology and similar metal-catalyzed procedures are presented, suggesting the occurrence of a visible-light EDA complex which generates the aryl radical with no need for an additional photocatalyst.
- Bartolomeu, Aloisio De A.,Brocksom, Timothy J.,De Oliveira, Kleber T.,No?l, Timothy,Silva, Rodrigo C.
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- A highly efficient and recyclable NiCl2(dppp)/PEG-400 system for Suzuki-Miyaura reaction of aryl chlorides with arylboronic acids
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NiCl2(dppp) in PEG-400 is shown to be a highly efficient catalyst for Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids. The reaction could be conducted at 100 °C using K3PO4 as base, yielding a variety of biaryls in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether and NiCl2(dppp)/PEG-400 system could be easily recycled and reused up to five times without significant loss of activity. Our system not only avoids the use of easily volatile and toxic dioxane or toluene as a solvent but also solves the basic problem of nickel catalyst reuse.
- Liao, Yang,Yang, Weisen,Wei, Ting,Cai, Mingzhong
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supporting information
p. 1134 - 1142
(2019/04/10)
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- Decarboxylative Suzuki-Miyaura coupling of (hetero)aromatic carboxylic acids using iodine as the terminal oxidant
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A novel methodology for the decarboxylative Suzuki-Miyaura-type coupling has been established. This process uses iodine or a bromine source as both the decarboxylation mediator and the terminal oxidant, thus avoiding the need for stoichiometric amounts of transition metal salts previously required. Our new protocol allows for the construction of valuable biaryl architectures through the coupling of (hetero)aromatic carboxylic acids with arylboronic acids. The scope of this decarboxylative Suzuki reaction has been greatly diversified, allowing for previously inaccessible non-ortho-substituted aromatic acids to undergo this transformation. The procedure also benefits from low catalyst loadings and the absence of stoichiometric transition metal additives.
- Quibell, Jacob M.,Duan, Guojian,Perry, Gregory J.P.,Larrosa, Igor
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supporting information
p. 6445 - 6448
(2019/06/07)
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- Synthesis, structure, and synthetic potential of arenediazonium trifluoromethanesulfonates as stable and safe diazonium salts
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Aromatic diazonium salts are valuable building blocks for organic synthesis; however, in most cases, they are unstable, unsafe, poorly soluble, and/or expensive. In this paper, we have shown that a variety of stable and safe arenediazonium triflates ArN2+ TfO– can be obtained easily and in high yields by diazotization of anilines with tert-butyl nitrite in the presence of trifluoromethanesulfonic acid. Arenediazonium triflates are relatively shelf-stable in the dry state. They dissolve well in water, as well as polar and even nonpolar organic solvents. Less than 800 J/g of energy is released during the thermal decomposition of these salts, which indicates their explosion safety. Arenediazonium triflates have a high reactivity in the known reactions of diazonium chemistry, and undergo an unusual metal-free chlorodediazonization reaction with chloroform and CCl4.
- Filimonov, Victor D.,Krasnokutskaya, Elena A.,Kassanova, Assia Zh.,Fedorova, Valentina A.,Stankevich, Ksenia S.,Naumov, Nikolay G.,Bondarev, Alexander A.,Kataeva, Veronika A.
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p. 665 - 674
(2018/09/14)
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- Palladium decorated on a new dendritic complex with nitrogen ligation grafted to graphene oxide: Fabrication, characterization, and catalytic application
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Immobilized Pd nanoparticles on a new ligand, namely, tris(pentaethylene-pentamine)triazine supported on graphene oxide (Pdnp-TPEPTA(L)-GO) was introduced as a novel and robust heterogeneous catalyst for use in C-C bond formation reaction. The Pdnp-TPEPTA(L)-GO catalyst was synthesized by complexation of Pd with TPEPTA as a ligand with high N-ligation sites that were supported on graphene oxide through 3-chloropropyltrimethoxysilane. The prepared catalyst was characterized using some microscopic and spectroscopic techniques. The TPEPTA(L)-GO substrate is a 2D heterogeneous catalyst with a high specific surface area and a large amount of N-ligation sites. The Pdnp-TPEPTA(L)-GO catalyst used in the C-C bond formation reaction between aryl or heteroaryl and phenylboronic acid derivatives was applied towards the synthesis of biaryl units in high isolated yields. Notably, a series of competing experiments were performed to establish the selectivity trends of the presented method. Also, this catalyst system was reusable at least six times without a significant decrease in its catalytic activity.
- Golestanzadeh, Mohsen,Naeimi, Hossein
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p. 27560 - 27573
(2019/09/12)
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- Urea-based organocatalyst catalyzed direct C–H bond arylations of unactivated arenes
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A simple 1,3-diethylurea was demonstrated to catalyze transition-metal-free arylations of unactivated aromatic C–H bonds with aryl iodides in the presence of t-BuOK. A broad range of aryl iodides with different arenes could couple in moderate to excellent yields. The mechanistic experiment results indicated that the radical is involved in this transformation.
- Zhao, Huaiqing,Xu, Xiangwen,Wu, Wei,Zhang, Wei,Zhang, Yunxian
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- [2,2′-bipyridin]-6(1 H)-one, a Truly Cooperating Ligand in the Palladium-Mediated C-H Activation Step: Experimental Evidence in the Direct C-3 Arylation of Pyridine
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The ligand [2,2′-bipyridin]-6(1H)-one (bipy-6-OH) has a strong accelerating effect on the Pd-catalyzed direct arylation of pyridine or arenes. The isolation of relevant intermediates and the study of their decomposition unequivocally show that the deprotonated coordinated ligand acts as a base and assists the cleavage of the C-H bond. Mechanistic work indicates that the direct arylation of pyridine with this ligand occurs through a Pd(0)/Pd(II) cycle. Because of this dual ligand-intramolecular base role, there is no need for an available coordination site on the metal for an external base, a difficulty encountered when chelating ligands are used in coupling reactions that involve a C-H cleavage step.
- Salamanca, Vanesa,Toledo, Alberto,Albéniz, Ana C.
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supporting information
p. 17851 - 17856
(2019/01/04)
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- Monoamine Oxidase (MAO-N) Whole Cell Biocatalyzed Aromatization of 1,2,5,6-Tetrahydropyridines into Pyridines
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A sustainable MAO-N biocatalyzed process for the synthesis of pyridines from aliphatic tetrahydropyridines (THP) has been developed. Pyridine compounds were synthesized under mild reaction conditions and with high conversion, exploiting MAO-N whole cells as aromatizing biocatalysts. The kinetic profile of the whole cell biocatalytic transformation was finally investigated via in situ 19F NMR.
- Toscani, Anita,Risi, Caterina,Black, Gary W.,Brown, Nicola L.,Shaaban, Ali,Turner, Nicholas J.,Castagnolo, Daniele
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p. 8781 - 8787
(2018/09/06)
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- tert-butoxide-promoted coupling of aryl iodides with arenes using Di-tert-butyl hyponitrite as an initiator
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The coupling reaction of aryl iodides with arenes was found to proceed under mild conditions to give biaryls through a homolytic aromatic substitution mechanism, using potassium tert-butoxide and di-tert-butyl hyponitrite as a stoichiometric promoter and a radical initiator, respectively.
- Kiriyama, Kazuya,Shirakawa, Eiji
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supporting information
p. 1757 - 1759
(2017/11/23)
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- Pyridine sulfinates as general nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions with aryl halides
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Pyridine rings are ubiquitous in drug molecules; however, the pre-eminent reaction used to form carbon-carbon bonds in the pharmaceutical industry, the Suzuki-Miyaura cross-coupling reaction, often fails when applied to these structures. This phenomenon is most pronounced in 2-substituted pyridines, and results from the difficulty in preparing, the poor stability of, and low efficiency in reactions of pyridine-2-boronates. We demonstrate that by replacing these boronates with pyridine-2-sulfinates, a cross-coupling process of unrivalled scope and utility is realized. The corresponding 3-And 4-substituted pyridine variants are also efficient coupling partners. In addition, we apply these sulfinates in a library format to the preparation of medicinally relevant derivatives of the drugs varenicline (Chantix) and mepyramine (Anthisan).
- Markovic, Tim,Rocke, Benjamin N.,Blakemore, David C.,Mascitti, Vincent,Willis, Michael C.
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p. 4437 - 4442
(2017/07/11)
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- Phosphonium Salts as Pseudohalides: Regioselective Nickel-Catalyzed Cross-Coupling of Complex Pyridines and Diazines
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Heterobiaryls are important pharmacophores that are challenging to prepare by traditional cross-coupling methods. An alternative approach is presented where pyridines and diazines are converted into heteroaryl phosphonium salts and coupled with aryl boronic acids. Nickel catalysts are unique for selective heteroaryl transfer, and the reaction has a broad substrate scope that includes complex pharmaceuticals. Phosphonium ions also display orthogonal reactivity in cross-couplings compared to halides, enabling chemoselective palladium- and nickel-catalyzed coupling sequences.
- Zhang, Xuan,McNally, Andrew
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p. 9833 - 9836
(2017/08/08)
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- Development of a Unique Heterogeneous Palladium Catalyst for the Suzuki–Miyaura Reaction using (Hetero)aryl Chlorides and Chemoselective Hydrogenation
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A unique heterogeneous palladium catalyst (7% Pd/WA30) supported on an anion exchange resin, which contains N,N-dimethylaminoalkyl functionalities on the polymer backbone, was developed. 7% Pd/WA30 could smoothly catalyze Suzuki–Miyaura reactions of even less reactive heteroaryl chlorides and heteroarylboronic acids to afford various (hetero)biaryls due to the electron-donating effect of the tert-amines on WA30 to Pd species. It was also applicable as a chemoselective hydrogenation catalyst, showing inactivity for the hydrogenolysis of tert-butyldimethylsilyl (TBS) ethers, alkyl benzyl ethers, and benzyl alcohols. The tert-amines on WA30 acted as moderate catalyst poisons for Pd, resulting in chemoselective hydrogenation. 7% Pd/WA30 was reused for at least five times without any loss of the hydrogenation catalytic activity. (Figure presented.).
- Ichikawa, Tomohiro,Netsu, Moeko,Mizuno, Masahiro,Mizusaki, Tomoteru,Takagi, Yukio,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 2269 - 2279
(2017/07/07)
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- An efficient and recoverable palladium organocatalyst for Suzuki reaction in aqueous media
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Meso-tetrakis[4-(methoxycarbonyl)phenyl]porphyrinatopalladium(II) as a palladium organocatalyst was synthesized and then used in aqueous media as a heterogeneous organocatalyst in Suzuki reaction. The prepared organocatalyst was characterized using UV–visible, infrared and NMR spectroscopies. It was found to be an efficient catalyst for Suzuki coupling reaction between phenylboronic acid and a broad range of aryl halides. Mild reaction conditions, water solvent as green media, and easy catalyst separation and reusability are the advantages of the presented method.
- Fareghi-Alamdari, Reza,Golestanzadeh, Mohsen,Bagheri, Omid
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- The use of organolithium reagents for the synthesis of 4-aryl-2-phenylpyridines and their corresponding iridium(III) complexes
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A versatile palladium-free route for the synthesis of 4-aryl-substituted phenylpyridines (ppy), starting from tert-butyl 4-oxopiperidine-1-carboxylate, is reported. Reaction with an aryllithium, followed by trifluoroacetic acid dehydration/deprotection and oxidation with 2-iodoylbenzoic acid and finally phenylation, gave 4 ligands (L1-4H): 2,4-diphenylpyridine, 4-(4-methoxyphenyl)-2-phenylpyridine, 2-phenyl-4-(o-tolyl)pyridine and 4-mesityl-2-phenylpyridine. These ligands were coordinated to iridium to give the corresponding Ir(L)2(A) complexes (Ir1-7), where A = ancillary ligand acetylacetate or 2-picolinate. This was used to demonstrate that, through a combination of ancillary ligand choice and torsional twisting between the 4-aryl substituents of the ppy ligands, it is possible to tune the phosphorescent emission of the complexes in the range 502-560 nm.
- Davidson, Ross,Hsu, Yu-Ting,Batchelor, Thomas,Yufit, Dmitry,Beeby, Andrew
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p. 11496 - 11507
(2016/07/26)
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- Synthesis and utility of dihydropyridine boronic esters
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When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products.
- Panda, Santanu,Coffin, Aaron,Nguyen, Q. Nhu,Tantillo, Dean J.,Ready, Joseph M.
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supporting information
p. 2205 - 2209
(2016/02/18)
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- Immobilized Pd(0) nanoparticles on phosphine-functionalized graphene as a highly active catalyst for Heck, Suzuki and N-arylation reactions
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In this study, a phosphine group was chemically grafted to the surface of graphene in order to prepare a reusable ligand with high surface area, incorporating a phosphine moiety. The treatment of graphene oxide (GO) with hydroxide followed by an aqueous work-up yields an OH-functionalized graphene material (GOH) via ring-opening of the epoxide groups. Reaction of GOH with chlorodiphenylphosphine (ClPPh2) gives a new material, GOPPh2 (PFG), which can be used for stabilization of metal nanoparticles or complexation of transition metals in order to prepare a reusable metal catalyst. Stabilization of palladium nanoparticles on the surface of GOPPh2 resulted in the production of an efficient heterogeneous Pd catalyst (PFG-Pd) for application in C-C and C-N bond formation reactions. The PFG-Pd catalyst was characterized using some different microscopic and spectroscopic techniques such as FT-IR, XRD, TEM, SEM, EDX, and ICP analysis. The applicability of the PFG-Pd catalyst was evaluated in Heck, Suzuki and N-arylation reactions. The catalyst system showed high catalyst activity in these processes and the target products were obtained in high isolated yields. The PFG-Pd catalyst was reusable in these reactions for at least 5 times with no significant decrease in its catalytic activity.
- Fareghi-Alamdari, Reza,Haqiqi, Mohsen G.,Zekri, Negar
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p. 1287 - 1296
(2016/02/19)
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- Enantioselective Synthesis of Chiral Piperidines via the Stepwise Dearomatization/Borylation of Pyridines
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We have developed a novel approach for the synthesis of enantioenriched 3-boryl-tetrahydropyridines via the Cu(I)-catalyzed regio-, diastereo-, and enantioselective protoborylation of 1,2-dihydropyridines, which were obtained by the partial reduction of the pyridine derivatives. This dearomatization/enantioselective borylation stepwise strategy provides facile access to chiral piperidines together with the stereospecific transformation of a stereogenic C-B bond from readily available starting materials. Furthermore, the utility of this method is demonstrated for the concise synthesis of the antidepressant drug (-)-paroxetine. A theoretical study of the reaction mechanism is also described.
- Kubota, Koji,Watanabe, Yuta,Hayama, Keiichi,Ito, Hajime
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supporting information
p. 4338 - 4341
(2016/05/09)
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- Palladium-catalyzed decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides
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Decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides is reported. Using a bimetallic system of Cu2O and Pd(PPh3)4, the scope of the reaction is demonstrated by the synthesis of 27 pyridine-containing biaryls in moderate to good yields.
- Chennamaneni, Lohitha Rao,William, Anthony D.,Johannes, Charles W.
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p. 1293 - 1296
(2015/03/04)
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- Photoinduced C-H direct arylation of unactivated arenes
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Two general protocols have been developed for the photoinduced, metal-free direct arylation of unactivated arenes with aryl iodide. Both methods gave good to excellent yields for most substrates. Notably, the C-F bond in method A and the C-F, C-Cl, and C-Br bonds in method B could survive the arylation reaction. These methods offered excellent options for syntheses of biaryls.
- Kan, Jian,Huang, Shijun,Zhao, Huaiqing,Lin, Jin,Su, Weiping
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p. 1329 - 1333
(2015/08/06)
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- Nickel-catalyzed one-pot synthesis of biaryls from phenols and arylboronic acids via C-O activation using TCT reagent
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In this study, the direct Nickel-catalyzed Suzuki-Miyaura coupling reaction of phenols and arylboronic acids via C-O bond activation using 2,4,6-trichloro-1,3,5-triazine (TCT) is described. Initially, phenols were reacted with TCT to give the corresponding 2,4,6-triaryloxy-1,3,5-triazine (TAT) products. Subsequently, arylboronic acid, base and Ni-catalyst were added to the generated aryl C-O electrophile to obtain the final biaryl product. This study represents a simple and direct method for the synthesis of biaryls from phenolic compounds using sub-stoichiometric amounts of TCT as a cheap and readily available C-O activating reagent.
- Iranpoor, Nasser,Panahi, Farhad,Jamedi, Fereshteh
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- Encapsulation enhanced dimerization of a series of 4-aryl-N- methylpyridinium derivatives in water: New building blocks for self-assembly in aqueous media
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The construction of supramolecular systems in aqueous media is still a great challenge owing to the limited sources of building blocks. In this study, a series of 4-aryl-N-methylpyridinium derivatives have been synthesized. They formed very stable host-gu
- Zhang, Ying,Zhou, Tian-You,Zhang, Kang-Da,Dai, Jin-Ling,Zhu, Yuan-Yuan,Zhao, Xin
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supporting information
p. 1530 - 1534
(2014/06/09)
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- AMVN-initiated expedient synthesis of biaryls by the coupling reaction of unactivated arenes and heteroarenes with aryl iodides
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The role of radical initiators AMVN and AIBN has been studied in the potassium tert-butoxide mediated biaryl coupling reaction of aryl iodides with unactivated arenes. Radical initiator AMVN promoted carbon-carbon bond formation expeditiously from aryl iodide having various groups such as amino, methoxy, fluoro, methyl, and trifluoromethyl and arenes in the presence of potassium tert-butoxide (4 equiv.) at 110 °C in 2-5 h. Substituted arenes such as toluene, xylene, anisole, and fluorobenzene also proceeded to form biaryls under AMVN-initiated reaction conditions. Moreover naphthalene, pyridine, pyrimidine, and pyridazine also coupled with aryl iodides and produced biaryls in 41-82% yields. It seems that AMVN initiates the formation of the aryl radical, which enters the radical chain reaction. The generated aryl radical may combine with the arene leading to a biaryl radical, which upon protonation gives the biphenyl radical anion and tert-butanol. The biphenyl radical anion finally reacts with the aryl iodide generating the aryl radical and thus completes the radical chain reaction with concomitant release of biphenyl.
- Bhakuni, Bhagat Singh,Yadav, Abhimanyu,Kumar, Shailesh,Kumar, Sangit
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p. 827 - 836
(2014/02/14)
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- p-toluenesulfonohydrazide as highly efficient initiator for direct C-H arylation of unactivated arenes
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p-Toluenesulfonohydrazide (PTSH) was shown to promote the highly efficient direct arylation of unactivated arenes with aryl iodides, bromides, or chlorides in the presence of potassium tert-butoxide without the assistance of any transition metals. The reaction proceeds through base-promoted homolytic aromatic substitution (BHAS) involving aryl radicals and arylradical anions as intermediates. (Chemical Equation Presented).
- Song, Qiao,Zhang, Dongmei,Zhu, Qihua,Xu, Yungen
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supporting information
p. 5272 - 5274
(2015/02/05)
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- Triarylbismuthanes as threefold aryl-transfer reagents in regioselective cross-coupling reactions with bromopyridines and quinolines
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Cross-coupling studies using bromopyridines and bromoquinolines with triarylbismuths as threefold coupling reagents in substoichiometric amounts under Pd-catalysed conditions are disclosed. The reactivity was high with both mono- and dibromopyridyl substrates, and mono- and bis-couplings were carried out regioselectively. A library of monoaryl and diaryl pyridines was formed in high yields. A one-pot strategy provided a simple and straightforward synthesis of both symmetrical and unsymmetrical diarylpyridines. Arylations of 2-bromo- and 3-bromoquinolines were achieved with triarylbismuth reagents. This study demonstrates that triarylbismuths may be used as threefold arylating reagents for the synthesis of aryl pyridines and quinolines through couplings with bromopyridines and bromoquinolines under Pd-catalysed conditions. Copyright
- Rao, Maddali L.N.,Dhanorkar, Ritesh J.
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supporting information
p. 5214 - 5228
(2014/10/15)
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- A general Suzuki cross-coupling reaction of heteroaromatics catalyzed by nanopalladium on amino-functionalized siliceous mesocellular foam
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Suzuki-Miyaura cross-coupling reactions of heteroaromatics catalyzed by palladium supported in the cavities of amino-functionalized siliceous mesocellular foam are presented. The nanopalladium catalyst effectively couples not only heteroaryl halides with
- Bratt, Emma,Verho, Oscar,Johansson, Magnus J,Baeckvall, Jan-Erling
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p. 3946 - 3954
(2014/05/20)
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- Palladium dichloride adduct of N,N-bis-(diphenylphosphanylmethyl)-2- aminopyridine: Synthesis, structure and catalytic performance in the decarboxylative cross-coupling of 4-picolinic acid with aryl bromide
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Reaction of PdCl2 with N,N-bis-(diphenylphosphanylmethyl)-2- aminopyridine (bdppmapy) afforded a mononuclear complex [(bdppmapy)PdCl 2] (1). Compound 1 was characterized by elemental analysis, IR, 1H, 13C and 31P NMR, electrospray ion mass spectra (ESI-MS) and X-ray single crystal crystallography. The Pd(ii) center in 1 is chelated by bdppmapy, showing a cis-square planar geometry. With the assistance of additive Cu2O, complex 1 exhibited good catalytic activity toward the decarboxylative cross-coupling reactions between 4-picolinic acid and aryl bromides. In the presence of only 2 mol% catalyst, a family of 4-aryl-pyridines could be isolated in up to 83% yield.
- He, Run-Tian,Wang, Jian-Feng,Wang, Hui-Fang,Ren, Zhi-Gang,Lang, Jian-Ping
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p. 9786 - 9794
(2014/06/23)
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- Direct arylation of n-heteroarenes with aryldiazonium salts by photoredox catalysis in water
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A highly effective visible light-promoted "radical-type" coupling of N-heteroarenes with aryldiazonium salts in water has been developed. The reaction proceeds at room temperature with [Ru(bpy)3]Cl 2×6 H2O as a photosensit
- Xue, Dong,Jia, Zhi-Hui,Zhao, Cong-Jun,Zhang, Yan-Yan,Wang, Chao,Xiao, Jianliang
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supporting information
p. 2960 - 2965
(2014/03/21)
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- SULFONAMIDE COMPOUNDS AND USES AS TNAP INHIBITORS
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Described herein are compounds that modulate the activity of TNAP. In some embodiments, the compounds described herein inhibit TNAP. In certain embodiments, the compounds described herein are useful in the treatment of conditions associated with hyper- mineralization.
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Paragraph 00198
(2013/09/12)
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- A macrocyclic aromatic pyridone pentamer as a highly efficient organocatalyst for the direct arylations of unactivated arenes
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A macrocyclic aromatic pyridone pentamer was shown to catalyze highly efficient transition-metal-free arylations of unactivated aromatic C-H bonds with aryl iodides and bromides in the presence of potassium tert-butoxide. The Royal Society of Chemistry.
- Zhao, Huaiqing,Shen, Jie,Guo, Juanjuan,Ye, Ruijuan,Zeng, Huaqiang
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supporting information
p. 2323 - 2325
(2013/06/26)
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- A self-assembled Pd6L8 nanoball for Suzuki-Miyaura coupling reactions in both homogeneous and heterogeneous formats
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A self-assembled nano-sized Pd6L8 (L = 1,3,5-tris(4′-pyridyloxadiazole)-2,4,6-triethylbenzene) ball was constructed based on a new oxadiazole-containing tripod. In H2O-EtOH mixed-solvent system, Pd(ii)-ball displays excellent performance in Suzuki-Miyaura cross-coupling reactions at low catalyst loading under ambient conditions in a homogeneous fashion. Furthermore, it shows heterogeneous catalyst nature in o-xylene and can be reused without loss of catalytic activity.
- Zhao, Chao-Wei,Ma, Jian-Ping,Liu, Qi-Kui,Yu, Yang,Wang, Peng,Li, Yan-An,Wang, Kui,Dong, Yu-Bin
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supporting information
p. 3150 - 3154
(2013/11/06)
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- Metal-free arylation of benzene and pyridine promoted by amino-linked nitrogen heterocyclic carbenes
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An amino-linked nitrogen heterocyclic carbene (amino-NHC), 1-tBu, has been shown to mediate carbon-carbon coupling through the direct C-H functionalization of benzene and pyridine in the absence of a metal catalyst. Using EPR, the first spectroscopic evidence corroborating the single electron transfer mechanism for the metal-free carbon-carbon coupling manifold, as reported by others, is introduced.
- Chen, Wen-Ching,Hsu, Yu-Chen,Shih, Wei-Chun,Lee, Ching-Yu,Chuang, Wen-Han,Tsai, Yi-Fang,Chen, Peter Ping-Yu,Ong, Tiow-Gan
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supporting information; experimental part
p. 6702 - 6704
(2012/07/14)
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- (NHC)palladium complexes from hydroxy-functionalized imidazolium salts as catalyst for the microwave-accelerated fluorine-free Hiyama reaction
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Palladium acetate reacts with 1-benzyl-3-(2-hydroxy-2-phenylethyl)-1H- imidazolium chloride to give the corresponding bis(carbene)palladium(II) complex 5 [(NHC)2PdCl2] by direct metalation. The X-ray diffraction structure of the complex is reported. In the presence of NaOH solution (50 % H2O, w/w) in air and under microwave irradiation, the bis(NHC)pallalium(II) complex 5 is an active precatalyst for the Hiyama coupling of aryl halides with trialkoxy(aryl)silanes, providing biaryls and heterobiaryls. For some deactivated aryl bromides and for aryl chlorides, the corresponding cross-coupling reactions require tetrabutylammonium bromide (TBAB) as additive. The fluoride-free Hiyama reactions are performed with low (NHC)palladium loadings (0.1 mol-%). The active catalyst can also be prepared in situ from Pd(OAc)2 and the corresponding imidazolium salt 4.
- Penafiel, Itziar,Pastor, Isidro M.,Yus, Miguel,Esteruelas, Miguel A.,Olivan, Montserrat,Onate, Enrique
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experimental part
p. 7174 - 7181
(2012/01/06)
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- A highly practical and reliable nickel catalyst for Suzuki-Miyaura coupling of aryl halides
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We disclose that [1,3-bis(diphenylphosphino)methane]nickel(II) chloride [NiCl2(dppp)] is a highly active, universally applicable, cheap, and stable catalyst for Suzuki-Miyaura cross-coupling reactions of aryl halides with a catalyst loading of lower than 1 mol%, and more notably, in the absence of extra supporting ligands. Under the optimized reaction conditions, a broad range of aryl bromides as well as the notoriously unreactive aryl chlorides, including activated, non-activated, deactivated, and heteroaromatic and sterically hindered substrates can be coupled smoothly with various boronic acids (47 examples, 48-98% yields). In addition, the transformation is tolerant of various functional groups such as ether, ester, ketone, aldehyde, cyano, and unprotected amino and hydroxy groups. Finally, the potential utilization of the methodology was further demonstrated by the gram-scale synthesis of several core structures of commercialized antihypertensive drugs and fungicides. Thus, the combination of high activity, broad applicability, cheapness, and high stability of NiCl2(dppp) presented in this work constitutes one of the few prominent catalysts which allow for practical and reliable construction of biaryls and heterobiaryls with structural diversity from readily available aryl halides and boronic acids. Copyright
- Zhao, Yu-Long,Li, You,Li, Shui-Ming,Zhou, Yi-Guo,Sun, Feng-Yi,Gao, Lian-Xun,Han, Fu-She
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supporting information; experimental part
p. 1543 - 1550
(2011/08/07)
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- Nickel-catalyzed cross-coupling of phenols and arylboronic acids through an in situ phenol activation mediated by PyBroP
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A new method for the Suzuki-Miyaura cross-coupling of phenols and arylboronic acids through in situ phenol activation mediated by PyBroP is presented. The reaction proceeds efficiently by using cost-effective, markedly stable [NiCl2(dppp)] (dppp=1,3-bis(diphenylphosphino)propane) as the catalyst in only 5 mol % loading, as well as in the absence of extra ligands. The method exhibits broad applicability and high efficiency towards a wide range of both phenols and boronic acids, including activated, nonactivated, deactivated, and heteroaromatic coupling partners. In addition, various functional groups, such as ether, amino, cyano, ester, and ketone groups, are compatible with this transformation. Notably, arylboronic acids containing an unprotected NH2 group and 2-heterocyclic boronic acids, which are generally problematic for coupling under conventional conditions, are also viable substrates, although moderate yields were obtained for sterically hindered substrates. Consequently, the in situ cross-coupling methodology coupled with the use of an inexpensive and stable nickel catalyst provides a rapid and efficient pathway for the assembly of biaryls and heterobiaryls with structural diversity from readily available phenol compounds.
- Chen, Guo-Jun,Huang, Jie,Gao, Lian-Xun,Han, Fu-She
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supporting information; experimental part
p. 4038 - 4042
(2011/05/05)
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- Ligand-promoted C3-selective arylation of pyridines with Pd catalysts: Gram-scale synthesis of (±)-preclamol
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The first example of Pd-catalyzed, C3-selective arylation of unprotected pyridines has been developed by employing a catalytic system consisting of Pd(OAc)2 and 1,10-phenanthroline. This protocol provides an expeditious route to an important class of 3-arylpyridines and 3-arylpiperidines frequently found in bioactive compounds. A brief synthesis of the drug molecule (±)-preclamol is also reported.
- Ye, Mengchun,Gao, Guo-Lin,Edmunds, Andrew J. F.,Worthington,Morris, James A.,Yu, Jin-Quan
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supporting information; experimental part
p. 19090 - 19093
(2012/01/07)
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- Aryl phosphoramides: useful electrophiles for suzuki-miyaura coupling catalyzed by a NiCl2/dppp system (dppp=1,3-bis(diphenylphosphino) propane)
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Chemical Equation presantation Suzuki-Miyaura coupling: We disclose a new strategy for phenol activation in the first Suzuki-Miyaura coupling of phenol derivatives activated by forming aryl bis(2-oxo-3-oxazolidinyl)phosphines as a highly efficient and broadly applicable methodology for the diverse synthesis of biaryls and heterobiaryls (see scheme). The use of readily available, stable NiCl2/dppp as the catalyst system also provides an important advance.
- Zhao, Yu-Long,Li, You,Li, Yu,Gao, Lian-Xun,Han, Fu-She
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supporting information; experimental part
p. 4991 - 4994
(2010/08/05)
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- Ligand-free and heterogeneous palladium on carbon-catalyzed hetero-suzuki-miyaura cross-coupling
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A ligand-free and heterogeneous palladium on carbon (Pd/C)-catalyzed hetero-SuzukiMiyaura coupling reaction has been developed. The protocol enables the construction of both heterocyclic-alicyclic and heterocyclic-heterocyclic biaryl derivatives in good to excellent yields. Furthermore, Pd/C could be reused. The time-course study clarified that palladium was leached into the reaction media as the reaction proceeded and then completely deposited on the carbon support.
- Kitamura, Yoshiaki,Sako, Satoko,Tsutsui, Azusa,Monguchi, Yasunari,Maegawa, Tomohiro,Kitade, Yukio,Sajiki, Hironao
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experimental part
p. 718 - 730
(2010/06/16)
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