- Metalated Porous Phenanthroline-Based Polymers as Efficient Heterogeneous Catalysts for Regioselective C?H Activation of Heteroarenes
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Direct C?H bond activation of heterocycles as a step-economical and environmentally friendly approach to build the heterobiaryls motifs is highly attractive, but it still has a challenge to design and prepare a cheap and regioselective heterogeneous catal
- Tang, Yongquan,Dai, Zhifeng,Wang, Sai,Chen, Fang,Meng, Xiangju,Xiao, Feng-Shou
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p. 2469 - 2474
(2021/08/06)
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- Programmed Synthesis of Tetra-Aryl Thiophenes with Stepwise, Ester-Controlled Regioselectivity
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Herein, we report a modular synthetic route to access tetra-arylated thiophene compounds with four different substituents with programmed chemical control provided by an ester activating/directing group. This method enables the functionalization of indivi
- Messina, Cynthia,Ottenwaelder, Xavier,Forgione, Pat
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supporting information
p. 7348 - 7352
(2021/10/01)
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- Light-Switchable and Self-Healable Polymer Electrolytes Based on Dynamic Diarylethene and Metal-Ion Coordination
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Self-healing polymer electrolytes are reported with light-switchable conductivity based on dynamic N-donor ligand-containing diarylethene (DAE) and multivalent Ni2+ metal-ion coordination. Specifically, a polystyrene polymer grafted with poly(ethylene glycol-r-DAE)acrylate copolymer side chains was effectively cross-linked with nickel(II) bis(trifluoromethanesulfonimide) (Ni(TFSI)2) salts to form a dynamic network capable of self-healing with fast exchange kinetics under mild conditions. Furthermore, as a photoswitching compound, the DAE undergoes a reversible structural and electronic rearrangement that changes the binding strength of the DAE-Ni2+ complex under irradiation. This can be observed in the DAE-containing polymer electrolyte where irradiation with UV light triggers an increase in the resistance of solid films, which can be recovered with subsequent visible light irradiation. The increase in resistance under UV light irradiation indicates a decrease in ion mobility after photoswitching, which is consistent with the stronger binding strength of ring-closed DAE isomers with Ni2+. 1H-15N heteronuclear multiple-bond correlation nuclear magnetic resonance (HMBC NMR) spectroscopy, continuous wave electron paramagnetic resonance (cw EPR) spectroscopy, and density functional theory (DFT) calculations confirm the increase in binding strength between ring-closed DAE with metals. Rheological and in situ ion conductivity measurements show that these polymer electrolytes efficiently heal to recover their mechanical properties and ion conductivity after damage, illustrating potential applications in smart electronics.
- Nie, Hui,Schauser, Nicole S.,Self, Jeffrey L.,Tabassum, Tarnuma,Oh, Saejin,Geng, Zhishuai,Jones, Seamus D.,Zayas, Manuel S.,Reynolds, Veronica G.,Chabinyc, Michael L.,Hawker, Craig J.,Han, Songi,Bates, Christopher M.,Segalman, Rachel A.,Read De Alaniz, Javier
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supporting information
p. 1562 - 1569
(2021/02/01)
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- Nickel-catalyzed and Li-mediated regiospecific C-H arylation of benzothiophenes
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A nickel-based catalytic system for the regiospecific C2-H arylation of benzothiophene has been established. NiCl2(bpy) is used as a catalyst in combination with LiHMDS as a base in dioxane. The catalytic system is applicable to a variety of functionalized benzothiophenes, as well as other heteroarenes including thiophene, benzodithiophene, benzofuran and selenophene in combination with iodo aryl electrophiles. The role of LiHMDS as a uniquely potent base and a postulated mechanism are discussed. The applicability of this system is finally demonstrated for the synthesis of an intermediate of an active pharmaceutical ingredient.
- Canivet, Jér?me,Grousset, Léonie,Hisler, Ga?lle,Mohr, Yorck,Quadrelli, Elsje Alessandra,Roux, Yoann,Wisser, Florian M.
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p. 3155 - 3161
(2020/06/19)
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- Well-Defined Palladium N-Heterocyclic Carbene Complexes: Direct C-H Bond Arylation of Heteroarenes
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A series of palladium N-heterocyclic carbene (NHC) complexes of type trans-{(NHC)PdCl2L} (L = C5H5N, 3-ClC5H4N, and PPh3) (3-5) have been developed as efficient precatalysts for direct C-H bond arylation of various heteroarenes. In particular, an in situ generated new NHC ligand derived from {1,3-di-(2,6-diethylphenyl)acenaphtho[1,2-d] imidazolium} chloride (2) is used for the stabilization of the palladium metal center. Among the screened palladium precatalysts (3-5), the most active PEPPSI themed complex (3) was successfully employed toward direct C-H bond arylation of various heteroarenes and aryl bromides. A range of functional groups on aryl bromides as well as on heteroarenes sustained throughout the standard reaction conditions for easy access of various arylated heterocyclic compounds. Significantly, the utility of the protocol was demonstrated by the effective synthesis of a precursor of raloxifene, a selective estrogen receptor modulator.
- Kumar, Anuj,Kumar, Manoj,Verma, Akhilesh K.
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p. 13983 - 13996
(2020/11/20)
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- A Convoluted Polyvinylpyridine-Palladium Catalyst for Suzuki-Miyaura Coupling and C?H Arylation
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The development of highly active and reusable supported catalysts for Suzuki-Miyaura coupling and catalytic C?H arylation is important for fundamental and applied chemistry, with these reactions being used to produce medical compounds and functional materials. Herein, we found that a mesoporous composite made of a linear poly(4-vinylpyridine) and tetrachloropalladate acted as a dual-mode catalyst for a variety of cross-coupling reactions, with both Pd nanoparticles and a Pd complex catalyst being observed under different conditions. The polyvinylpyridine-palladium composite 1 was readily prepared via the molecular convolution of poly(4-vinylpyridine) and sodium tetrachloropalladate to provide a hardly soluble polymer-metal composite. The Suzuki-Miyaura coupling and the C?H arylation of aryl chlorides and bromides with arylboronic acids, thiophenes, furans, benzene, and anisole proceeded in the presence of 0.004 mol% (40 mol ppm) to 1 mol% Pd of 1 to afford the corresponding coupling products in high yields. Furthermore, the catalyst was reused without an appreciable loss of activity. Pharmaceutical compounds and functional materials were synthesized via the coupling reactions. N2 gas adsorption/desorption analysis indicated that the catalyst had a mesoporous nature, which played a crucial role in the catalysis. In the Suzuki-Miyaura couplings, in situ generated palladium nanoparticles in the polymer matrix were catalytically active, while a polymeric Pd(II) complex was crucial in the C?H arylations. These catalytic species were investigated via XAFS, XPS, far-infrared absorption, and Raman spectroscopies, as well as DFT calculations. (Figure presented.).
- Ohno, Aya,Sato, Takuma,Mase, Toshiaki,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information
p. 4687 - 4698
(2020/09/07)
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- Light-Controllable Ionic Conductivity in a Polymeric Ionic Liquid
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Polymeric ionic liquids (PILs) have attracted considerable attention as electrolytes with high stability and mechanical durability. Light-responsive materials are enabling for a variety of future technologies owing to their remote and noninvasive manipula
- Dolinski, Neil D.,Hawker, Craig J.,Hu, Jerry,Nie, Hui,Read de Alaniz, Javier,Schauser, Nicole S.,Segalman, Rachel A.
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supporting information
p. 5123 - 5128
(2020/02/11)
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- Palladium-Catalyzed Methylation of Aryl, Heteroaryl, and Vinyl Boronate Esters
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A method for the direct methylation of aryl, heteroaryl, and vinyl boronate esters is reported, involving the reaction of iodomethane with aryl-, heteroaryl-, and vinylboronate esters catalyzed by palladium and PtBu2Me. This transformation occurs with a remarkably broad scope and is suitable for late-stage derivatization of biologically active compounds via the boronate esters. The unique capabilities of this method are demonstrated by combining carbon-boron bond-forming reactions with palladium-catalyzed methylation in a tandem transformation.
- Haydl, Alexander M.,Hartwig, John F.
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supporting information
p. 1337 - 1341
(2019/02/26)
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- Trimethylphosphate as a Methylating Agent for Cross Coupling: A Slow-Release Mechanism for the Methylation of Arylboronic Esters
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A methyl group on an arene, despite its small size, can have a profound influence on biologically active molecules. Typical methods to form a methylarene involve strong nucleophiles or strong and often toxic electrophiles. We report a strategy for a new, highly efficient, copper and iodide co-catalyzed methylation of aryl- and heteroarylboronic esters with the mild, nontoxic reagent trimethylphosphate, which has not been used previously in coupling reactions. We show that it reacts in all cases tested in yields that are higher than those of analogous copper-catalyzed reactions of MeOTs or MeI. The combination of C-H borylation and this methylation with trimethylphosphate provides a new approach to the functionalization of inert C-H bonds and is illustrated by late-stage methylation of four medicinally active compounds. In addition, reaction on a 200 mmol scale demonstrates reliability of this method. Mechanistic studies show that the reaction occurs by a slow release of methyl iodide by reaction of PO(OMe)3 with iodide catalyst, rather than the typical direct oxidative addition to a metal center. The low concentration of the reactive electrophile enables selective reaction with an arylcopper intermediate, rather than nucleophilic groups on the arylboronate, and binding of tert-butoxide to the boronate inhibits reaction of the electrophile with the tert-butoxide activator to form methyl ether.
- He, Zhi-Tao,Li, Haoquan,Haydl, Alexander M.,Whiteker, Gregory T.,Hartwig, John F.
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supporting information
p. 17197 - 17202
(2018/12/14)
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- Accessing Heterobiaryls through Transition-Metal-Free C-H Functionalization
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Herein we report a transition-metal-free synthetic protocol for heterobiaryls, one of the most important pharmacophores in the modern drug industry, employing a new multidonor phenalenyl (PLY)-based ligand. The current procedure offers a wide substrate scope (24 examples) with a low catalyst loading resulting in an excellent product yield (up to 95%). The reaction mechanism involves a single electron transfer (SET) from a phenalenyl-based radical to generate a reactive heteroaryl radical. To establish the mechanism, we have isolated the catalytically active SET initiator, characterizing by a magnetic study.
- Banik, Ananya,Paira, Rupankar,Shaw, Bikash Kumar,Vijaykumar, Gonela,Mandal, Swadhin K.
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p. 3236 - 3244
(2018/03/23)
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- Alkynylthioimidazolium Salts: Efficient Reagents for the Synthesis of Alkynyl Sulfides by Electrophilic Thioalkynylation
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The efficient synthesis of a series of alkynylthioimidazolium salts through reaction of organozinc compounds with dibromo(imidazolium)sulfuranes is reported. Addition of Grignard reagents to these new species provided a highly modular, clean, and scalable access to a broad variety of alkynyl sulfides in good-to-excellent yields. The utility of this protocol was showcased by the preparation of alkynyl sulfides, which are particularly difficult to obtain or simply unavailable through the existing methodologies. In addition, the synthetic method was extended to the preparation of alkynyl selenides.
- Pe?a, Javier,Talavera, Garazi,Waldecker, Bernd,Alcarazo, Manuel
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- On the Route to the Photogeneration of Heteroaryl Cations. the Case of Halothiophenes
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2-Chloro-, 2-bromo-, and 2-iodothiophenes undergo photochemical dehalogenation via the triplet state. In the presence of suitable π-bond nucleophiles, thienylation occurs with modest yield from chloro and bromo derivatives (via photogenerated triplet 2-thienyl cation). Specific trapping by using oxygen along with computational analysis carried out by means of a density functional method support that, in the case of iodo derivatives, homolytic thienyl-I bond fragmentation occurs first and heteroaryl cations are formed by electron transfer within the triplet radical pair, thus opening an indirect access to such cations.
- Raviola, Carlotta,Chiesa, Francesco,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
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p. 6336 - 6342
(2016/08/16)
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- Direct C-H Arylation of Heteroarenes with Copper Impregnated on Magnetite as a Reusable Catalyst: Evidence for CuO Nanoparticle Catalysis in Solution
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A reusable copper-based catalyst system was employed for the direct arylation of electron-rich heteroarenes. Under mild and operationally simple reaction conditions good yields and selectivities were obtained using diaryliodonium salts as coupling partners. A combination of experimental methods including kinetic studies, filtration tests, and a series of analytical tools (TXRF, ICP-MS, SEM, XPS, TEM, EFTEM) provide evidence for catalytically active soluble nanoparticles formed from an amorphous heterogeneous precursor. Mechanistic studies hint at a redox-neutral process which promotes counterion dissociation from the diaryliodonium salt by a copper(II) oxide species.
- Vásquez-Céspedes, Suhelen,Chepiga, Kathryn M.,M?ller, Nadja,Sch?fer, Andreas H.,Glorius, Frank
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p. 5954 - 5961
(2016/09/09)
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- Modification of organic compounds with Lawesson's reagent
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Application in organic synthesis of Lawesson's reagent, 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, provides a possibility to replace an oxygen atom for a sulfur atom in the carbonyl group of ketones, esters, amides, in ether group, and also either to induce a rearrangement of the initial structure of organic compounds with or without inclusion of sulfur atoms or to lead to the formation of various types of organophosphorus compounds. The formed organosulfur compounds exhibit a wide range of biological action.
- Kayukova,Praliyev,Gut'Yar,Baitursynova
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p. 148 - 160
(2015/04/14)
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- Remarkable ligand effect of P(2-MeOC6H4)3 on palladium-catalyzed direct arylation
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Palladium-catalyzed direct arylation polymerization (DArP) has recently attracted much attention as a simple and easy means of synthesizing π-conjugated polymers. We have reported a novel catalytic system for DArP. While the already known catalytic system
- Wakioka, Masayuki,Nakamura, Yuki,Montgomery, Michelle,Ozawa, Fumiyuki
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p. 198 - 205
(2015/01/30)
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- Palladium nanoparticles embedded on thiourea-modified chitosan: A green and sustainable heterogeneous catalyst for the Suzuki reaction in water
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Palladium nanoparticles (PdNPs) embedded on thiourea modified chitosan (TMC) are prepared in spherical and cubical shapes by intercalating palladium(ii) acetate in TMC, a natural bio-polymer, and a subsequent reduction using ellagic acid (EA) as a natural and green reducing source in water. The formation of palladium nanoparticles in water is monitored by UV-Vis, spectroscopy and the PdNPs/TMC solid matrix are characterized by FT-IR, powder XRD and HR-TEM. The amount of palladium entrapped on TMC is measured by ICP-OES analysis, and it is found to be 0.00103 mol%. The synthesised PdNPs/TMC reported for the first time, were employed as heterogeneous catalysts for Suzuki cross-coupling reactions of aryl iodide/bromide with various substituted aryl boronic acids in water and showed high catalytic activity under mild reaction conditions. Easy separation, the absence of an inert atmosphere and good to excellent yields are the other significant outcomes of this protocol. In addition, the reactions also work well with various heterocyclic boronic acids. Also the catalyst can be easily recovered and reused for at least five runs without loss in its activity.
- Affrose, Abdullah,Suresh, Palaniswamy,Azath, Ismail Abulkalam,Pitchumani, Kasi
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p. 27533 - 27539
(2015/03/30)
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- Aerobic and Efficient Direct Arylation of Five-Membered Heteroarenes and Their Benzocondensed Derivatives with Aryl Bromides by Bulky α-Hydroxyimine Palladium Complexes
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In the present work, a series of α-hydroxyimine palladium complexes with bulky substituents (i.e., {[Ar-N=C(R)-C(R)2-OH]PdCl2} (C1, R = Me, Ar = 2-diphenylmethyl-4,6-dimethylphenyl; C2, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-methylphenyl; C3, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-methyoxylphenyl; C4, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-chlorophenyl; C5, R = Ph, Ar = 2,6-dimethylphenyl; C6, R = Ph, Ar = 2,6-diisopropylphenyl)) were synthesized and characterized. The structures of palladium complexes C1 and C2 were determined by X-ray diffraction. These bidentate N,O-palladium complexes were applied for direct arylation under aerobic conditions. The effects of the reaction conditions and ligand substitution on the catalytic activity were evaluated. Upon a low palladium loading of 0.5 mol %, the bulky palladium complex C6 was successfully used to catalyze the cross-coupling of a variety of five-membered heteroarenes and their benzo-condensed derivatives with (hetero)aryl bromides. The mechanistic investigation on the direct arylation supported the involvement of a Pd(0)/Pd(II) CMD process.
- Luo, Bao-Tian,Liu, Huan,Lin, Zhi-Jie,Jiang, Jingxing,Shen, Dong-Sheng,Liu, Rui-Zhi,Ke, Zhuofeng,Liu, Feng-Shou
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p. 4881 - 4894
(2015/11/09)
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- A palladium-nanoparticle and silicon-nanowire-array hybrid: A platform for catalytic heterogeneous reactions
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We report the development of a silicon nanowire array-stabilized palladium nanoparticle catalyst, SiNA-Pd. Its use in the palladium-catalyzed Mizoroki-Heck reaction, the hydrogenation of an alkene, the hydrogenolysis of nitrobenzene, the hydrosilylation of an α,β-unsaturated ketone, and the C-H bond functionalization reactions of thiophenes and indoles achieved a quantitative production with high reusability. The catalytic activity reached several hundred-mol ppb of palladium, reaching a TON of 2 000 000. An array of reactions: A silicon-nanowire-array-stabilized palladium-nanoparticle catalyst, SiNA-Pd, was designed and used in the palladium-catalyzed Mizoroki-Heck reaction. It can catalyze a variety of other reactions and has a high reusability. Copyright
- Yamada, Yoichi M. A.,Yuyama, Yoshinari,Sato, Takuma,Fujikawa, Shigenori,Uozumi, Yasuhiro
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supporting information
p. 127 - 131
(2014/01/17)
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- Direct C-H arylation of thiophenes at low catalyst loading of a phosphine-free bis(alkoxo)palladium complex
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An efficient phosphine-free direct C-H arylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1-0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or electron-withdrawing groups. The reactivities of the 2- and 5-positions of thiophenes are equivalent and not dependent on steric hindrance under optimal conditions. This condition can also be applied to other heterocyclic moieties such as benzothiophene, benzofuran, and pyrrole with high conversion yields.
- Li, Yabo,Wang, Jingran,Huang, Mengmeng,Wang, Zhiwei,Wu, Yusheng,Wu, Yangjie
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p. 2890 - 2897
(2014/05/06)
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- Factors controlling the reactivity of heteroarenes in direct arylation with arylpalladium acetate complexes
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The palladium-catalyzed direct arylation of heteroarenes with aryl halides has emerged as a viable alternative to conventional cross-coupling reactions. This paper reports a detailed mechanistic study on factors controlling the reactivity of heteroarenes in direct arylation with well-defined models of the presumed intermediate [PdAr(O2CMe-κ2O)L] (1). Although recent theoretical studies have provided a reasonable description of the mechanism of C-H bond cleavage by 1, its model compounds so far tested have been evidently less reactive than that expected. We found that [PdPh(O 2CMe-κ2O)(PPh3)] (1a) and [Pd(2,6-Me 2C6H3)(O2CMe-κ2O) (PPh3)] (1c), generated in situ from isolated [PdPh(μ-O 2CMe)(PPh3)]2 (4a) and [Pd(2,6-Me 2C6H3)(μ-O2CMe)(PPh 3)]4 (4c), respectively, react with a variety of heteroarenes in almost quantitative yields. The reactivity order of heteroarenes was evaluated by competitive reactions, showing that benzothiazole (8) is significantly less reactive than 2-methylthiophene (6), despite the acidity of 8 (pKa = 27) being much higher than that of 6 (pKa = 42). This reason was examined by kinetic experiments using 1c as well as DFT calculations using the model compound [PdPh(O2CMe- κ2O)(PH3)] (1d). Both heteroarenes reacted with 1 via a sequence of three elementary processes (i.e., substrate coordination, C-H bond cleavage, and C-C reductive elimination), but their energy profiles were significantly different from each other. The reaction of 6 obeyed simple second-order kinetics, and the deuterium-labeling experiments and DFT calculations indicated the occurrence of rate-determining reductive elimination. On the other hand, the reaction of 8 displayed saturation kinetics due to the occurrence of relatively stable coordination of 8 prior to C-H bond cleavage. This coordination stability enhances the activation barrier for C-H bond cleavage, thereby causing the modest reactivity of 8. Thus, although the previous mechanistic studies on direct arylation have been focused largely on the C-H bond cleavage process, not only the C-H bond cleavage but also the substrate coordination and C-C reductive elimination must be considered.
- Wakioka, Masayuki,Nakamura, Yuki,Hihara, Yoshihiro,Ozawa, Fumiyuki,Sakaki, Shigeyoshi
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p. 4423 - 4430
(2013/09/02)
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- Direct access to pyrazolo(benzo)thienoquinolines. Highly effective palladium catalysts for the intramolecular C-H heteroarylation of arenes
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A short and atom-efficient strategy to obtain a series of pyrazolo(benzo)thienoquinolines is developed. Alternative catalytic systems for the key intramolecular direct heteroarylation of arenes are presented and include the first example of C-H (hetero)arylation of (hetero)arenes catalyzed by very low catalyst loadings of a palladium source.
- Churruca, Fatima,Hernandez, Susana,Perea, Maria,SanMartin, Raul,Dominguez, Esther
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supporting information
p. 1413 - 1415
(2013/02/25)
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- Direct arylation of 2-methylthiophene with isolated [PdAr(μ-O 2CR)(PPh3)]n complexes: Kinetics and mechanism
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The palladium-catalyzed direct arylation of aromatic compounds with aryl halides has been proposed to involve an arylpalladium carboxylate intermediate. However, isolated arylpalladium complexes, which undergo C-H bond cleavage of aromatic substrates without the aid of additional activators or promoters, have been scarcely documented. This paper reports that [PdAr(μ-O 2CR)(PPh3)]n complexes (1: Ar = Ph, 2-MeC 6H4, 2,6-Me2C6H3; R = Me, tBu) successfully react with 2-methylthiophene (2) in the absence of additives to afford 5-aryl-2-methylthiophenes (3) in high yields. The reactivity increases with increasing bulkiness of the Ar group, whereas the bulky pivalate ligand (R = tBu) reduces the reactivity as compared with the acetate ligand (R = Me). Complex 1 is in equilibrium with the monomeric species [PdAr(O2CR-κ2O)(PPh3)] (5) in solution, as confirmed by IR spectroscopy. Kinetic examinations have suggested that the direct arylation proceeds via 5, which undergoes C-H bond cleavage of 2. Complex 1 serves as a good catalyst for direct arylation of 2 with aryl bromides.
- Wakioka, Masayuki,Nakamura, Yuki,Wang, Qifeng,Ozawa, Fumiyuki
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experimental part
p. 4810 - 4816
(2012/10/08)
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- TBAF-assisted palladium-catalyzed Suzuki reaction in water under the ligand and base-free conditions
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Tetrabutyl ammonium fluoride (abbreviated as TBAF)-assisted palladium-catalyzed Suzuki reaction in neat water has been demonstrated under the ligand and base-free conditions. The cross-coupling of aryl or heteroaryl bromides with arylboronic acids generated the corresponding products in good to excellent yields in the presence of low concentration of palladium acetate in combination with TBAF under air.
- Wu, Xiang-Mei,Gu, Yong-Bing
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experimental part
p. 396 - 400
(2012/10/07)
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- Generation of metalated thiophenes with Grignard reagent and catalytic secondary amine for the cross coupling reaction with aryl halides
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The reaction of thiophene derivatives with Grignard reagent (EtMgCl) and a catalytic amount of amine (Cy2NH) induced the metalation at the α-position. Following addition of several aryl halides in the presence of a nickel or palladium catalyst afforded C-H arylated products in good to excellent yields. The method was successfully applied to facile synthesis of differently-substituted 2,5-diarylthiophenes.
- Tanaka, Shota,Tanaka, Daiki,Sugie, Atsushi,Mori, Atsunori
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experimental part
p. 1173 - 1176
(2012/03/26)
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- Efficient Pd-catalyzed direct arylations of heterocycles with unreactive and hindered aryl chlorides
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A highly electron-rich Pd complex can efficiently catalyze the direct arylation of heteroaromatics with unreactive and sterically congested aryl chlorides.
- Ghosh, Debalina,Lee, Hon Man
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supporting information
p. 5534 - 5537,4
(2012/12/12)
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- Asymmetric hydrogenation of thiophenes and benzothiophenes
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An efficient and highly asymmetric ruthenium-N-heterocyclic carbene-catalyzed hydrogenation of substituted thiophenes and benzothiophenes is described, providing a new strategy for the formation of valuable enantiomerically pure tetrahydrothiophenes and 2,3-dihydrobenzothiophenes.
- Urban, Slawomir,Beiring, Bernhard,Ortega, Nuria,Paul, Daniel,Glorius, Frank
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supporting information
p. 15241 - 15244
(2012/11/07)
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- Direct arylation of heteroarenes catalyzed by a palladium-1,10- phenanthroline complex
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A new entry in direct arylation of heteroarenes using Pd(OAc)2 and 1,10-phenanthroline as a nitrogen-based ligand is reported. The long induction period observed at the initial stage of the reaction was effectively reduced by modification of th
- Takita, Ryo,Fujita, Daichi,Ozawa, Fumiyuki
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supporting information; experimental part
p. 959 - 963
(2011/06/17)
-
- Fluoride-promoted cross-coupling of chloro(mono-, di-, or triphenyl)germanes with aryl halides in "moist" toluene. Multiple transfer of the phenyl group from organogermane substrates and comparison of the coupling efficiencies of chloro(phenyl)germanes with their corresponding stannane and silane counterparts
-
The trichlorophenyl-, dichlorodiphenyl-, and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of tetrabutylammonium fluoride in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two, or three phenyl groups from the organogermanes. The corresponding chlorophenylstannanes were found to be more reactive than chlorophenylsilanes, which in turn were more effective than chlorophenylgermanes. One chloride ligand on the Ge or Si center allows efficient activation by fluoride to promote transfer of up to three aryl groups from germane or silicon. However, no haloligand was necessary to be present on the Sn center, since tetraphenyltin efficiently transferred up to four phenyl groups during fluoride-promoted couplings with aryl halides. 19F NMR studies suggested formation of the fluorophenylgermanes and the hypervalent germanate species as possible intermediates.
- Pitteloud, Jean-Philippe,Zhang, Zun-Ting,Liang, Yong,Cabrera, Laura,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 8199 - 8212
(2011/03/18)
-
- A general catalyst for the β-selective C - H bond arylation of thiophenes with iodoarenes
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Open access: The normally less-reactive β position of thiophenes was previously inaccessible to direct functionalization. However, the β selectivity observed with the catalytic system PdCl2/P{OCH(CF 3)2}3/Ag2CO3 in the arylation of thiophenes with iodoarenes (see scheme) is a remarkably general phenomenon applicable to unsubstituted, monosubstituted, and disubstituted thiophene derivatives, as well as thiophene-containing fused aromatic compounds.
- Ueda, Kirika,Yanagisawa, Shuichi,Yamaguchi, Junichiro,Itami, Kenichiro
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supporting information; experimental part
p. 8946 - 8949
(2011/02/21)
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- Arylchlorogermanes/TBAF/ moist toluene: A promising combination for Pd-catalyzed germyl-stille cross-coupling
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Chemical equation presented The trichlorophenyl,- dichlorodiphenyl,- and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of TBAF in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two, or three phenyl groups from the organogermane precursors.
- Zhang, Zun-Ting,Pitteloud, Jean-Philippe,Cabrera, Laura,Liang, Yong,Toribio, Myrdich,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 816 - 819
(2010/04/06)
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- Sulfamic acid as efficient and reusable catalytic system for the synthesis of pyrrole, furan, and thiophene derivatives
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Sulfamic acid has been utilized for the first time as an efficient and reusable catalytic system for the synthesis of heteroaromatics such as pyrrole, furan, and thiophene derivatives from 1,4-diketones. This new procedure offers significant improvements in the reaction rates and yields in a shorter reaction time and a lower reaction temperature contrasted with the reported results. The recovered catalyst can be reused for subsequent runs with only a gradual decrease in activity. The most important feature is that the reaction process is homogeneous whereas the separation process is heterogeneous, which is often seen in other catalysts, and so it is a good character for technical application.
- Luo, Haitang,Kang, Yuru,Li, Qi,Yang, Liming
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p. 144 - 148
(2008/09/18)
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- Alkylated 2,2′-bithiophenes and 2-phenylthiophenes in the composition of pyrolysis products of high-sulfur kerogen
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Compounds from the 5-n-alkyl-2,2′-bithiophene, 5-n-alkyl-5′- methyl-2,2′-bithiophene, 5-n-alkyl-2-phenylthiophene, and 5-n-alkyl-2-o-tolylthiophene homologous series were synthesized to prove their presence in the pyrolysis products of sulfur-rich kerogen. A study of the pyrolysis products of sulfur-vulcanized polybutadiene confirmed that these compounds can be formed via the thermal transformation of n-alkyl polysulfur-bound fragments of sulfur-rich kerogen. The earlier proposed scheme that assumes the dependence of the composition of the pyrolysis products of sulfur-rich kerogen on its saturation with sulfide bridges was experimentally corroborated. Nauka/Interperiodica 2007.
- Bushnev
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p. 184 - 192
(2008/09/21)
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- Thionation using fluorous Lawesson's reagent
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Thionation of amides, 1,4-diketones, N-(2-oxoalkyl)amides, N,N-acylhydrazines, and acyl-protected uridines with the use of a fluorous analogue of the Lawesson's reagent leads to thioamides, thiophenes, 1,3-thiazoles, 1,3,4-thiadiazoles, and acyl-protected 4-thiouridines. The isolation of the final products in high yields is achieved in most cases by a simple filtration (fluorous solid-phase extraction).
- Kaleta, Zoltan,Makowski, Brian T.,Soos, Tibor,Dembinski, Roman
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p. 1625 - 1628
(2007/10/03)
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- Synthesis of 2,5-disubstituted thienosultines and their thermal reactions with dienophiles and nucleophiles
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The 2,5-disubstituted thienosultines (5,7-disubstituted 1,4-dihydro-1H-3λ4-thieno[3,4-d][2,3]oxathiin-3-oxides) 5a-d were prepared from the corresponding dichlorides 4a-d with the commercially available Rongalite (sodium formaldehyde sulfoxylat
- Liu, Wen-Dar,Chi, Chih-Chin,Pai, I-Feng,Wu, An-Tai,Chung, Wen-Sheng
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p. 9267 - 9275
(2007/10/03)
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- A one-pot synthesis of thiophene and pyrrole derivatives from readily accessible 3,5-dihydro-1,2-dioxines
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A one-pot synthesis of 2,5-disubstituted thiophene, 1,2,5-tri- and 2,5-disubstituted pyrrole derivatives from readily available 3,5-dihydro-1,2-dioxines is described. The reaction proceeds by an initial Kornblum-de la Mare rearrangement of the 3,5-dihydro-1,2-dioxine to its isomeric 1,4-diketone followed by condensation of the in situ 1,4-diketone with sulfur, ammonia or a primary amine.
- Hewton, Cassie E,Kimber, Marc C,Taylor, Dennis K
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p. 3199 - 3201
(2007/10/03)
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- Fulgimide derivatives
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A fulgimide derivative of the formula: STR1 wherein R1, R2, R3 are independently alkyl cycloalkyl aryl etc.; R4 is thienyl, indolyl, furyl, etc.; X is a divalent organic residue; and R is amino, OH, etc., or a v
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- Preparation of 1,4-Diketones and Their Reactions with Bis(trialkyltin) or Bis(triphenyltin) Sulfide-Boron Trichloride
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1,4-Diphenyl- and 1,4-bis(4-chlorophenyl)-1.4-butanediones (3 and 4), as well as 1-phenyl-, 1-(4-chlorophenyl)-, and 1-(4-methoxyphenyl)-1,4-pentanediones (7-9) react with bis(tributyltin), bis(tricyclohexyltin), and/or bis(triphenyltin) sulfide in the pr
- Freeman, Fillmore,Kim, Darrick S. H. L.,Rodriguez, Eloy
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p. 1722 - 1727
(2007/10/02)
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- REACTION OF ARYLFURANES WITH HYDROGEN SULFIDE AND HYDROGEN SELENIDE UNDER CONDITIONS OF ACID CATALYSIS
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For the first time arylsubstituted furanes have been reacted with hydrogen sulfide and hydrogen selenide under the influence of proton acids.The respective arylthiophenes and arylselenophenes were obtained.
- Kharchenko, V. G.,Voronin, S. P.,Gubina, T. I.,Markushina, I. A.,Oleinik, A. F.
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p. 1321 - 1323
(2007/10/02)
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