- A silicon-heteroaromatic system as photosensitizer for light-driven hydrogen production by hydrogenase mimics
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The utilization of light and inexpensive catalysts to afford hydrogen represents a huge challenge. Following our interest in silicon-containing [FeFe]-hydrogenase ([FeFe]-H2ase) mimics, we report a new model approach for a photocatalytic [FeFe]-H2ase mimic 1, which contains a 1-silafluorene unit as a photosensitizer. Thereby, the photoactive ligand is linked to the [2Fe2S] cluster through S-CH2-Si bridges. Photochemical H2 evolution experiments were performed and revealed a turnover number (TON) of 29. This is the highest reported photocatalytic efficiency for an [FeFe]-H2ase model complex in which the photosensitizer is covalently linked to the catalytic center. We report a viable synthetic pathway for the construction of a new photoactive model of the [FeFe]-hydrogenase ([FeFe]-H2ase) active site with a dithiolate bridge and 1-silafluorene as a photosensitizer. The [FeFe]-H2ase mimic represents a very compact, easily accessible, and inexpensive photocatalyst for hydrogen generation. Copyright
- Goy, Roman,Apfel, Ulf-Peter,Elleouet, Catherine,Escudero, Daniel,Elstner, Martin,Goerls, Helmar,Talarmin, Jean,Schollhammer, Philippe,Gonzalez, Leticia,Weigand, Wolfgang
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- 9-Silafluorene and 9-germafluorene: Novel platforms for highly efficient red phosphorescent organic light-emitting diodes
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Two novel heterofluorene motifs consisting of the group 14 elements Si and Ge were developed as robust molecular platforms for the construction of organic light-emitting diode (OLED) materials. These two compounds exhibited similar photophysical properties, thermal stabilities and electrochemical behaviors except for the charge transport abilities. The red OLED hosted by a 9-silafluorene derivative (DPS) with Ir(MDQ)2(acac) as the emitter exhibited state-of-the-art current efficiency, power efficiency, and external quantum efficiency (EQE) with maxima of 50.7 cd A-1, 44.7 lm W-1, and 28.3%, respectively. In addition, the maximum EQE of a 9-germafluorene derivative (DPG)-based red device could reach 20%. These results indicated the great potential of group 14 element derivatives in the construction of highly efficient OLED materials.
- Liu, Xiang-Yang,Tian, Qi-Sheng,Zhao, Danli,Ran, Quan,Liao, Liang-Sheng,Fan, Jian
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- Transition-Metal-Free Approach for the Direct Arylation of Thiophene: Experimental and Theoretical Investigations towards the (Het)-Aryne Route
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This paper presents the results of our investigations on the arylation of thiophene using the transition-metal-free “aryne coupling” methodology. The reaction was studied by both experiment and computation (density functional theory) and comparison with phenyllithium was established. In parallel, the effects of the ligand and the salt on the coupling reaction were examined. The results underline the remarkable effect of such additives on the coupling reaction and the potency of the method to construct hetaryl–aryl backbones which open up promising access to a wide range of heterobiaryl structures using the novel “Het-Aryne” route.
- Demangeat, Catherine,Saied, Tarak,Ramozzi, Romain,Ingrosso, Francesca,Ruiz-Lopez, Manuel,Panossian, Armen,Leroux, Frédéric R.,Fort, Yves,Comoy, Corinne
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- On-surface synthesis of planar acenesviaregioselective aryl-aryl coupling
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The reaction of 2,2'-dibromo-biphenyl on a Ag(111) surface leads to the formation of planar acenes with a high-regioselectivity rather than nonplanar saddle-shaped tetraphenylene as the typical product in solution chemistry. The regioselective aryl-aryl coupling reaction is attributed to the hydrogen repulsion between the reactants on the confined two-dimensional surface.
- Feng, Lin,Wang, Tao,Jia, Hongxing,Huang, Jianmin,Han, Dong,Zhang, Wenzhao,Ding, Honghe,Xu, Qian,Du, Pingwu,Zhu, Junfa
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- REGIOSELECTIVE DIMETALLIERUNG VON AROMATEN. BEQUEMER ZUGANG ZU 2,2'-DISUBSTITUIERTEN BIPHENYLDERIVATEN
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Lithiation of biphenyl with 2.4 mol of n-butyllithium in the presence of TMEDA led directly to the 2,2'-dilithio derivative (I) in modest, but preparatively useful yields.I, in turn, was converted to a variety of products.The activation of the 2'-position of 2-lithiobiphenyl was shown directly by a separate experiment.MNDO calculations indicate stabilization in I by double bridging and in 2-lithiobiphenyl by intramolecular ? interaction of Li with the o-phenyl group.Similar interactions in substitution transition states rationalize the specificity of the reactions observed.
- Neugebauer, Wolfgang,Kos, Alexander J.,Schleyer, Rague
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- Direct Observation of Aggregation-Induced Emission Mechanism
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The mechanism of aggregation-induced emission, which overcomes the common aggregation-caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward–Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications.
- Corminboeuf, Clémence,Guan, Jianxin,Han, Han,Lin, Kun-Han,Liu, Jitian,Peng, Jie,Prlj, Antonio,Wei, Rong,Yu, Zhihao,Zhao, Dahui,Zheng, Junrong
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- Efficient construction of biaryls and macrocyclic cyclophanes via electron-transfer oxidation of Lipshutz cuprates
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An efficient method for the homocoupling of aryl halides by electron-transfer oxidation of Lipshutz cuprates (Ar2Cu(CN)Li 2) with organic electron acceptors is disclosed. Thus, various types of Lipshutz cuprates are prepared by successive treatment of aryl or heteroaryl bromides with tert-butyllithium and CuCN. The electron-transfer oxidation of Lipshutz cuprates with p-benzoquinones proceeds smoothly to afford the corresponding homocoupling products in moderate to good yields. Furthermore, it can be applied to the construction of either thiophene- or benzene-fused 10-membered ring cyclophanes. For the synthesis of 10-membered cyclophanes, the linear C-Cu-C structure of Lipshutz cuprates should be maintained in the dimetallacyclic intermediates, producing the large ring cyclophanes efficiently. The X-ray analysis of the cyclophanes reveals that the difference in the bridging atoms results in the different conformations of the macrocyclic rings. Thus, the silicon-bridged cyclophane 5a adopts a D2-symmetric structure with a twisted rhombic arrangement of four thiophene rings, whereas the methylene- and oxygen-bridged cyclophanes 5b and 5c possess C2h- and C2-symmetric structures with chair- and boatlike conformations, respectively. The 1H NMR spectrum of C2-symmetric 5c is temperature-dependent, and the activation energy (ΔG?) for the conformational change is 10.1 kcal/mol.
- Miyake, Yoshihiro,Wu, Mo,Rahman, M. Jalilur,Kuwatani, Yoshiyuki,Iyoda, Masahiko
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- Pd(OAc)2/PPh3-catalyzed desulfonylative homocoupling of arylsulfonyl chlorides
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The Pd-catalyzed homodimerization with respect to arylsulfonyl chlorides as an efficient method for the synthesis of biaryls has been developed. This desulfonylative reaction which was performed at reflux in 1,4-dioxane for 4 h under air afforded the desired products in good to excellent yields. The Pd(OAc)2/PPh3-catalyzed desulfonylative homodimerization of arenesulfonyl chlorides as an efficient method for the synthesis of biaryls was described. The corresponding products were obtained in good to excellent yields.
- Zhao, Qiao,Chen, Liangshun,Lang, Hongyue,Wu, Shengying,Wang, Limin
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- BN-phenanthryne: Cyclotetramerization of an 1,2-azaborine derivative
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Thermolysis of 9-azido-9-borafluorene in heptane solution produces the tetramer of a BN-phenanthryne. The isolation of the self-trapping product provides evidence for the involvement of the BN-aryne in the thermolysis reaction. Its formation may be rationalized by denitrogenation of the azide and ring enlargement. Making a first appearance: A BN-aryne analogous to 9,10-phenanthryne can be formed by thermolysis of the 9-azido-9-borafluorene and can undergo cyclotetramerization.
- Mueller, Matthias,Bettinger, Holger F.,Maichle-Moessmer, Caecilia
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- ortho-Phenylene-Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis
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While many foldamer systems reliably fold into well-defined secondary structures, higher order structure remains a challenge. A simple strategy for the organization of folded subunits in space is to link them together within a macrocycle. Previous work has shown that o-phenylenes can be co-assembled with rod-shaped linkers into twisted macrocycles, showing an interesting synergy between folding and thermodynamically controlled macrocyclization. In these systems the foldamer units were largely decoupled from each other both conformationally and electronically. Here, we show that hydrocarbon macrocycles, with very short ethenylene linkers, can be assembled from o-phenylenes using olefin metathesis. Characterization by NMR spectroscopy, X-ray crystallography, and ab initio calculations shows that the products are approximately triangular trimer macrocycles with helical o-phenylene corners in a heterochiral configuration. Their photophysics are dominated by the 4,4'-diphenylstilbene moieties, the longest conjugated segments, with further conjugation broken by the twisting of the o-phenylenes.
- Hartley, C. Scott,Kirinda, Viraj C.,Schrage, Briana R.,Ziegler, Christopher J.
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- Connecting two phenazines with a four-membered ring: The synthesis, properties and applications of cyclobuta[1,2-: B:3,4- b ′]diphenazines
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Herein we report cyclobuta[1,2-b:3,4-b′]diphenazine (CBDP), a new π-electron molecular scaffold containing two phenazine moieties connected by a four-membered ring. With properly positioned silylethynyl substituting groups, CBDP offers a chromophore with
- Yang, Shuaijun,Chu, Ming,Miao, Qian
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- Silicon-Heteroaromatic [FeFe] Hydrogenase Model Complexes: Insight into Protonation, Electrochemical Properties, and Molecular Structures
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To learn from Nature how to create an efficient hydrogen-producing catalyst, much attention has been paid to the investigation of structural and functional biomimics of the active site of [FeFe]-hydrogenase. To understand their catalytic activities, the μ
- Goy, Roman,Bertini, Luca,G?rls, Helmar,De Gioia, Luca,Talarmin, Jean,Zampella, Giuseppe,Schollhammer, Philippe,Weigand, Wolfgang
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- Convenient One-Pot Synthesis of 9 H -Carbazoles by Microwave Irradiation Employing a Green Palladium-Based Nanocatalyst
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An efficient palladium-catalyzed tandem reaction for the one-pot synthesis of 9 H -carbazoles under microwave irradiation is developed. This approach involves a sequential Buchwald-Hartwig amination and a direct arylation from affordable and inexpensive anilines and 1,2-dihaloarenes. For the development of this purpose, a novel and magnetically recoverable palladium nanocatalyst supported on a green biochar under ligand-free conditions is used. Compared to other existing palladium-based protocols, the present synthetic methodology shows a drastic reduction in reaction times and excellent compatibility with different functional groups allowing to obtain a small library of 9 H -carbazoles in high yields and with good regioselectivity. This procedure represents the first example in the direct synthesis of carbazoles using a heterogeneous palladium nanocatalyst from commercial precursors. To examine the application of this protocol, a direct and scalable synthesis of the bioactive carbazole alkaloid clausenalene from commercially available starting materials is described.
- Steingruber, H. Sebastián,Mendioroz, Pamela,Volpe, María A.,Gerbino, Darío C.
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p. 4048 - 4058
(2021/08/03)
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- "benchtop" Biaryl Coupling Using Pd/Cu Cocatalysis: Application to the Synthesis of Conjugated Polymers
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Typically, Suzuki couplings used in polymerizations are performed at raised temperatures in inert atmospheres. As a result, the synthesis of aromatic materials that utilize this chemistry often demands expensive and specialized equipment on an industrial scale. Herein, we describe a bimetallic methodology that exploits the distinct reactivities of palladium and copper to perform high yielding aryl-aryl dimerizations and polymerizations that can be performed on a benchtop under ambient conditions. These couplings are facile and can be performed by simple mixing in the open vessel. To demonstrate the utility of this method in the context of polymer synthesis: polyfluorene, polycarbazole, polysilafluorene, and poly(6,12-dihydro-dithienoindacenodithiophene) were created at ambient temperature and open to air.
- Minus, Matthew B.,Moor, Sarah R.,Pary, Fathima F.,Nirmani,Chwatko, Malgorzata,Okeke, Brandon,Singleton, Josh E.,Nelson, Toby L.,Lynd, Nathaniel A.,Anslyn, Eric V.
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supporting information
p. 2873 - 2877
(2021/05/05)
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- Synthesis of triphenylene derivatives by Pd-catalyzed Suzuki coupling/intramolecular C–H activation between arylboronic acids and dibromobiphenyls
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An efficient and regioselective synthesis of functionalized triphenylenes via palladium-catalyzed Suzuki-Miyaura coupling and subsequent intramolecular C–H activation between arylboronic acids and dibromobiphenyls was developed. This methodology showed excellent atomic economy and regiospecificity as well as synthetic feasibility of unsymmetrical triphenylenes.
- Tu, Jingxuan,Li, Gaoqiang,Zhao, Xiaoqian,Xu, Feng
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supporting information
p. 44 - 47
(2018/11/30)
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- Mixed er-NHC/phosphine Pd(ii) complexes and their catalytic activity in the Buchwald-Hartwig reaction under solvent-free conditions
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A series of novel (NHC)PdCl2-PR3 complexes were synthesized and fully characterized by 1H, 13C, 31P NMR and FT-IR spectroscopy. These complexes showed high catalytic activity toward solvent-free Buchwald-Hartwig amination. Both primary and secondary amines were efficiently utilized under the same reaction conditions. The solvent-free synthesis of valuable N-aryl carbazoles and similar N-heterocyclic systems was described.
- Ageshina, Alexandra A.,Sterligov, Grigorii K.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.,Chesnokov, Gleb A.,Gribanov, Pavel S.,Nechaev, Mikhail S.,Asachenko, Andrey F.,Bermeshev, Maxim V.,Melnikova, Elizaveta K.
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supporting information
p. 3447 - 3452
(2019/04/30)
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- 2-bromine-9,9-dimethyl silicon fluorene and synthesis method thereof
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The invention discloses 2-bromine-9,9-dimethyl silicon fluorene and a synthesis method thereof. The synthesis method comprises the following steps: step 1) carrying out coupling reaction between o-dibromobenzene and n-butyllithium to generate 2,2'-dibromobiphenyl, wherein the molar ratio of the o-dibromobenzene to the n-butyl lithium is 1:(0.48-0.55); step 2) carrying out bromination reaction between the 2,2'-dibromobiphenyl formed in step 1) and bromine to generate 2,2',4-tribromobiphenyl, wherein the molar ratio of 2,2'-dibromobiphenyl to the bromine is 1:(1-1.5); step 3) carrying out ring-closure reaction of the 2,2',4-tribromobiphenyl generated in step 2) and dichlorodimethylsilane to generate the 2-bromine-9,9-dimethyl silicon fluorene, wherein the molar ratio of the 2,2',4-tribromobiphenyl to the dichlorodimethylsilane is 1:(1-1.3).
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(2019/07/04)
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- Organic Electronic Device
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The present invention relates to an organic electronic device, comprising a first electrode (11), a second electrode (14), and, between the first and the second electrode, a substantially organic layer (13) comprising a heterocyclic compound bearing at least one lithoxy group and containing at least one heterocyclic ring comprising a phosphine oxide group directly bound to three carbon atoms; a compound for use in such an organic electronic device and to a semiconducting material comprising the respective compound.
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Paragraph 0090; 0154-0157
(2018/12/02)
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- ORGANIC COMPOUND, AND ORGANIC LIGHT EMITTING DIODE AND ORGANIC LIGHT EMITTING DISPLAY DEVICE INCLUDING THE SAME
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The present invention provides an organic compound for an organic light emitting diode. An example of the organic compound is represented by:
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Paragraph 0143; 0144
(2018/05/24)
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- Palladium-Catalyzed Fluoroarylation of gem-Difluoroalkenes
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A Pd-catalyzed fluoroarylation of gem-difluoroalkenes with aryl halides is reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derived from the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.
- Tang, Hai-Jun,Lin, Ling-Zhi,Feng, Chao,Loh, Teck-Peng
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supporting information
p. 9872 - 9876
(2017/08/08)
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- Synthesis and electroluminescence properties of new blue dual-core OLED emitters using bulky side chromophores
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Using a 1-anthracen-9-yl-pyrene (AP) dual-core emitter, two new emitters of blue light, 1-spiro-9,9′-bifluoren-4-yl-6-(10-spiro-9,9′-bifluoren-4-yl-anthracen-9-yl)-pyrene (DSF-AP) and 1-[2-(9H-carbazol-9-yl)phenyl]-6-[2-(9H-carbazol-9-yl)phenyl-anthracen-9-yl]-pyrene (DCP-AP), were synthesized through boration and the Suzuki aryl-aryl coupling reaction. These two materials exhibited PLmax values at 443?nm and 448?nm in a chloroform solution, and at 458?nm and 463?nm in a thin-film state. EL devices with the synthesized compounds were fabricated in the following configuration: ITO/4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)triphenylamine (2-TNATA) (60?nm)/N,N′-bis (naphthalene-1-yl)-N,N′-bis(phenyl)benzidine (NPB) (15?nm)/synthesized blue light-emitting materials (35?nm)/Tris-(8-hydroxyquinoline)aluminum (Alq3) (20?nm)/lithium fluoride (LiF) (1?nm)/Al (200?nm). Compared with the device made using an AP core lacking side groups, the device made with DCP-AP displayed 31% higher luminance efficiency (resulting in a value of 4.37?cd/A) and 32% higher power efficiency (to yield 1.93?lm/W), as well as a high external quantum efficiency (3.64%).
- Lee, Suji,Kim, Beomjin,Jung, Hyocheol,Shin, Hwangyu,Lee, Hayoon,Lee, Jaehyun,Park, Jongwook
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p. 255 - 261
(2016/09/07)
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- Mitigation of NADPH oxidase 2 activity as a strategy to inhibit peroxynitrite formation
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Using high throughput screening-compatible assays for superoxide and hydrogen peroxide, we identified potential inhibitors of the NADPH oxidase (Nox2) isoform from a small library of bioactive compounds. By using multiple probes (hydroethidine, hydropropidine, Amplex Red, and coumarin boronate) with well defined redox chemistry that form highly diagnostic marker products upon reaction with superoxide (O2. ), hydrogen peroxide (H2O2), and peroxynitrite (ONOO), the number of false positives was greatly decreased. Selected hits for Nox2 were further screened for their ability to inhibit ONOO formation in activated macrophages. A new diagnostic marker product for ONOO is reported. We conclude that the newly developed high throughput screening/reactive oxygen species assays could also be used to identify potential inhibitors of ONOO formed from Nox2-derived O2 and nitric oxide synthase- derived nitric oxide.
- Zielonka, Jacek,Zielonka, Monika,Verplank, Lynn,Cheng, Gang,Hardy, Micael,Ouari, Olivier,Ayhan, Mehmet Menaf,Podsiad?y, Rados?aw,Sikora, Adam,Lambeth, J. David,Kalyanaraman, Balaraman
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p. 7029 - 7044
(2016/05/11)
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- Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation
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A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.
- Shi, Guangfa,Chen, Dushen,Jiang, Hang,Zhang, Yu,Zhang, Yanghui
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supporting information
p. 2958 - 2961
(2016/07/06)
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- Pd(OAc)2 catalyzed homocoupling of arenediazonium salts in ionic liquids: Synthesis of symmetrical biaryls
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A facile, high yielding, and simple method for the synthesis of a library of symmetrical biaryls by homocoupling of arenediazonium salts is reported, employing catalytic amounts of Pd(OAc)2 and the readily available imidazolium ionic liquids (ILs), without oxidants, ligands, additives, or volatile solvents. Simple product isolation and recycling/reuse of the IL represent additional advantages of this method.
- Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 663 - 667
(2016/01/26)
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- Palladium-Catalyzed Annulation of 2,2 ′ -Dibromobiphenyls with Alkynes: Synthesis of Functionalized Phenanthrenes and Dibenzochrysenes
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A palladium-catalyzed annulation process of 2,2′-dibromobiphenyls with alkynes for the synthesis of functionalized phenanthrenes has been realized. The methodology provides an efficient approach to dibenzochrysene derivatives starting from simple reactants in two steps.
- Ma, Jun,Li, Gaoqiang,Qiao, Yan,Tu, Jingxuan,Liu, Sha,Xu, Feng
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supporting information
p. 1991 - 1996
(2015/09/01)
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- CYCLIC GERMANIUM COMPOUNDS AND APPLICATIONS THEREOF
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The present disclosure provides a new series of compounds exhibiting high fluorescence quantum yields in the solid state. In one embodiment, the compounds include a series of 2,3,4,5-tetraphenylgermoles with the same or different 1,1-substituents. In anot
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Paragraph 0142
(2015/06/24)
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- Iron carbonyl cluster-incorporated Cu(i) NHC complexes in homocoupling of arylboronic acids: An effective [TeFe3(CO)9]2- ligand
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A new type of TeFe3(CO)9-incorporated dicopper NHC complex was obtained directly from one-pot reactions. By the introduction of the cluster anion [TeFe3(CO)9]2- and NHCs as the ligands, these di-Cu(i)-based complexes exhibited pronounced catalytic activities toward the homocoupling of arylboronic acids with low Cu loadings and high yields (up to 98%).
- Lin, Chien-Nan,Huang, Chung-Yi,Yu, Chia-Chi,Chen, Yen-Ming,Ke, Wei-Ming,Wang, Guan-Jung,Lee, Gon-Ann,Shieh, Minghuey
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supporting information
p. 16675 - 16679
(2015/10/06)
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- Three-component coupling based on flash chemistry. Carbolithiation of benzyne with functionalized aryllithiums followed by reactions with electrophiles
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A flow microreactor method for three-component coupling of benzyne was developed based on flash chemistry. o-Bromophenyllithium generated from 1-bromo-2-iodobenzene and a functionalized aryllithium generated from the corresponding aryl halide were mixed at -70 °C. In the subsequent reactor o-bromophenyllithium is decomposed to generate benzyne without affecting the functionalized aryllithium at -30 °C, and carbolithiation of benzyne with the aryllithium took place spontaneously. The resulting functionalized biaryllithium was reacted with an electrophile in the subsequent reactor to give the corresponding three-component coupling product. The precise optimization of reaction conditions using the temperature-residence time mapping is responsible for the success of the present transformation. The present method has been successfully applied to the synthesis of boscalid.
- Nagaki, Aiichiro,Ichinari, Daisuke,Yoshida, Jun-Ichi
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supporting information
p. 12245 - 12248
(2014/11/08)
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- Palladium-catalyzed R2(O)P directed C(sp2)-H acetoxylation
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A novel and efficient Pd-catalyzed C-H acetoxylation is described. The approach uses R2(O)P as a directing group to synthesize various substituted 2′-phosphorylbiphenyl-2-OAc compounds. Notably, the reaction exhibits smooth operation under mild conditions and shows good functional group tolerance. Products are obtained with high selectivity and yields. This journal is the Partner Organisations 2014.
- Zhang, Heng,Hu, Rong-Bin,Zhang, Xiao-Yu,Li, Shi-Xia,Yang, Shang-Dong
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supporting information
p. 4686 - 4689
(2014/05/06)
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- Aerobic homocoupling of arylboronic acids catalysed by copper terephthalate metal-organic frameworks
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Copper terephthalate MOF is utilised as an environmentally benign, efficient and reusable heterogeneous catalyst to effect the aerobic homocoupling of arylboronic acids yielding the corresponding symmetrical biphenyls under mild reaction conditions. This method tolerates various substituents present in arylboronic acids such as halogens, cyano and nitro groups. The catalytic performance has been compared with that of other copper based MOFs namely MOF-101, [Cu(pdc)2]NH2Me2, [Cu 2(ndc)2ted]n and [Cu(H2L)] n as well as with other copper salt catalysts. Sheldon test confirmed the heterogeneity of the catalyst, which can be reused under optimized conditions with only a minor loss in its activity. A mechanism for the homocoupling reaction is also proposed. The simplicity of catalyst preparation, its stability, substrate selectivity, easy recovery and regeneration designate possible utilization of this catalytic system in a multitude of catalytic reactions and industrial processes. the Partner Organisations 2014.
- Puthiaraj, Pillaiyar,Suresh, Palaniswamy,Pitchumani, Kasi
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p. 2865 - 2875
(2014/05/06)
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- PROCESS FOR THE PREPARATION OF METALLOCENE COMPLEXES
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The invention relates to a process comprising the step of reacting a 2-indenylpinacolyl borane compound with a bromosubstituted compound in the presence of a Pd catalyst and a base to form the corresponding bridged bis(indenyl) ligand. This process step is very efficient and leads to less (homocoupled) byproducts than other known processes. The process of the invention may further comprise the step of reacting a 2-bromo indene compound with pinacolborane in the presence of a Pd catalyst and a base, to form the corresponding 2-indenylpinacolylborane compound. With this, the invention provides an improved and easy two-step process to prepared bridged bis(indenyl)ligands. These bridged bis(indenyl)ligands may suitably be used in the preparation of metallocene complexes, such as 2,2'-bis(2-indenyl)biphenyl ZrCI2 and 1,2-bis(2-indenyl)benzene ZrCI2. These metallocene complexes may be used for the polymerization, optionally in the presence of a cocatalyst, of one or more a-olefins, preferably for the polymerization of ethylene. In a preferred embodiment, the Pd catalyst is preferably is(triphenylphosphin)palladium dichloride (PPh3)2PdCI2).
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(2013/07/05)
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- PROCESS FOR THE PREPARATION OF METALLOCENE COMPLEXES
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The invention relates to a process comprising the step of (a) reacting a 2- indenylboranic acid (ester) with a bromosubstituted compound in the presence of the Pd catalyst bis(triphenylphosphin)palladium dichloride (PPh3)2PdCI2) and a base to form the corresponding bridged bis(indenyl) ligand. In case the 2-indenylboranic acid (ester) is the pinacolester of 2-indenylboranic acid, the process of the invention may further comprise the step of reacting a 2-bromo indene compound with pinacolborane in the presence of a Pd catalyst and a base, to form the corresponding 2- indenylpinacolylborane compound. With this, the invention provides an improved and easy two-step process to prepared bridged bis(indenyl)ligands, which is commercially very attractive when the Pd catalyst bis(triphenylphosphin)palladium dichloride (PPh3)2PdCI2) is used. Bridged bis(indenyl)ligands may suitably be used in the preparation of metallocene complexes, such as 2,2'-bis(2-indenyl)biphenyl ZrCI2 and 1,2-bis(2-indenyl)benzene ZrCI2. These metallocene complexes may be used for the polymerization, optionally in the presence of a cocatalyst, of one or more a-olefins, preferably for the polymerization of ethylene.
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(2013/07/05)
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- Palladium-catalyzed silyl C(sp3)-H bond activation
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The first transition-metal-catalyzed activation of silyl C(sp 3)-H bond was realized and synthetically applied. A variety of organic skeletons substituted with SiMe3 groups could undergo the Pd-catalyzed intramolecular coupling react
- Liang, Yun,Geng, Weizhi,Wei, Junnian,Ouyang, Kunbing,Xi, Zhenfeng
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supporting information; experimental part
p. 1537 - 1542
(2012/03/22)
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- Construction of benzosiloles, six- and eight-membered silacyclic skeletons, via a Pd-catalyzed intramolecular Mizoroki-Heck reaction of vinylsilanes
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A variety of silacycles including benzosiloles, six- and eight-membered silacyclic skeletons, were efficiently synthesized via a Pd-catalyzed intramolecular Mizoroki-Heck reaction of vinylsilanes.
- Ouyang, Kunbing,Liang, Yun,Xi, Zhenfeng
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supporting information
p. 4572 - 4575
(2012/11/07)
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- A concise synthetic approach towards hydroxytetraphenylenes
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This communication is concerned with our efforts in improving the syntheses of five hydroxytetraphenylens, which we obtained before. A short consecutive direct ortho-metalation and oxidative coupling sequence from N-pivaloyl-protected substituted aniline provided the corresponding 2,2-diiodobiphenyls. Subsequently, copper(II)-mediated oxidative coupling of 2,2-diiodobiphenyls successfully led to the formation of the corresponding hydroxytetraphenylenes. This is the first time that hydroxytetraphenylenes 2, 4 and 5 were all realized via oxidative cross-coupling reactions from the corresponding 2,2-diiodobiphenyls. Georg Thieme Verlag Stuttgart · New York.
- Cui, Jian-Fang,Huang, Hui,Wong, Henry N. C.
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scheme or table
p. 1018 - 1022
(2011/06/17)
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- Palladium-catalyzed synthesis of benzosilolo[2,3- b ]indoles via cleavage of a C(sp3)-Si bond and consequent intramolecular C(sp 2)-Si coupling
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An efficient process involving Pd-catalyzed selective cleavage of a C(sp3)-Si bond and consequent intramolecular C(sp2)-Si coupling has been developed, affording benzosilolo[2,3-b]indoles as a new type of silicon-bridged polyheteroarene in excellent yields. Aldehyde was found for the first time to be able to promote the efficiency of the catalytic process remarkably.
- Liang, Yun,Zhang, Shaoguang,Xi, Zhenfeng
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supporting information; experimental part
p. 9204 - 9207
(2011/08/06)
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- ANTHRACENE DERIVATIVES AND ORGANIC ELECTROLUMINESCENT DEVICE USING SAME
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Provided are a novel anthracene derivative and an organic light-emitting device using the same, and more particularly, an anthracene derivative having a core (e.g., an indenoanthracene core) where an anthracene moiety with excellent device characteristics is fused with a fluorene moiety or the like with excellent fluorescent properties, wherein an aryl group is introduced at the core, and an organic light-emitting device using the anthracene derivative, which is enhanced in efficiency, operating voltage, lifetime, etc.
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- LIGHT-EMISSION MATERIAL AND ORGANIC LIGHT-EMITTING DIODE INCLUDING THE SAME
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The invention provides a light-emission material comprising a compound having Formula (I): , wherein each of A independently is: each of Rm independently is H, alkyl, alkenyl, alkynyl, CN, CF3, alkylamino, amino, alkoxy, halo, aryl, or heteroaryl.
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- Decarboxylative homocoupling of (hetero)aromatic carboxylic acids
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A variety of hetero(aromatic) carboxylic acids are shown to undergo decarboxylative homocoupling, mediated by a Pd/Ag system. This novel methodology for the synthesis of symmetrical biaryls avoids the use of haloarenes and organometallic compounds as starting materials.
- Cornella, Josep,Lahlali, Hicham,Larrosa, Igor
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supporting information; experimental part
p. 8276 - 8278
(2010/12/19)
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- Functionalized benzylic magnesium reagents through a sulfur-magnesium exchange
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(Chemical Equation Presented) Switch it: lodobiphenyl thioethers readily undergo an iodine-magnesium exchange followed by, after the addition of tBuOLi, an intramolecular sulfur-magnesium exchange, which provides benzylic magnesium reagents in excellent yield through a fragmentation reaction.
- Stoll, Armin H.,Krasovskiy, Arkady,Knochel, Paul
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p. 606 - 609
(2007/10/03)
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- Poly(9,9-dialkyl-3,6-dibenzosilole) - A high energy gap host for phosphorescent light emitting devices
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The preparation of the 3,6-disubstituted dibenzosilole monomers 4, 5 and 10 by two different routes is described; Suzuki copolymerisation afforded poly(9,9-dioctyl-3,6-dibenzosilole) 11 which has a sufficiently high triplet energy (2.55 eV) to function as a host for green electrophosphorescent emitters. The Royal Society of Chemistry 2005.
- Chan, Khai Leok,Watkins, Scott E.,Mak, Chris S. K.,McKiernan, Mary J.,Towns, Carl R.,Pascu, Sofia I.,Holmes, Andrew B.
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p. 5766 - 5768
(2007/10/03)
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- Homocoupling of aryl iodides and bromides using a palladium/indium bimetallic system
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Homocoupling of aryl iodides and bromides using catalytic amounts of palladium and stoichiometric amounts of indium proceeded smoothly to afford the corresponding biaryls in good to high yields. Copyright Taylor & Francis, Inc.
- Chang, Yu Mi,Lee, Seung Hwan,Cho, Min Young,Yoo, Byung Woo,Rhee, Hak June,Lee, Sang Ho,Yoon, Cheol Min
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p. 1851 - 1857
(2007/10/03)
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- ORGANIC ELECTROLUMINESCENT ELEMENT
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The novel compound of the present invention has the diphenylanthracene structure at the center and a specific structure substituted with an aryl group at end portions. The organic electroluminescence device of the present invention comprises a plurality of layers of thin films of organic compounds which comprise a light emitting layer or a plurality of layers comprising a light emitting layer and are disposed between a pair of electrodes and at least one of the layers of thin films of organic compounds comprises the above novel compound. The novel compound exhibits excellent efficiency of light emission and heat resistance, has a long life and emits bluish light having excellent purity of color and the organic electroluminescence device comprises the novel compound and exhibits the same advantageous properties.
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- Metallocene compositions
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This invention relates to metallocene compositions and their use in the preparation of catalyst systems for olefin polymerization, particularly propylene polymerization. In one embodiment, the metallocenes of the present invention may be represented by th
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- Role of Copper Species in the Oxidative Dimerization of Arylboronic Acids: Synthesis of Symmetrical Biaryls
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Certain Cu(I) and Cu(II) salts are able to mediate the dimerization of arylboronic acids in DMF. They provide the corresponding symmetrical biaryls in moderate to very good yields. It is possible to run the reaction catalytically under an oxygen atmosphere without a significant loss of yields.
- Demir, Ayhan S.,Reis, Oemer,Emrullahoglu, Mustafa
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p. 10130 - 10134
(2007/10/03)
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- Structure and chemistry of 1-silafluorenyl dianion, its derivatives, and an organosilicon diradical dianion
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1-Silafluorene dianion was synthesized by potassium reduction of 1,1-dichloro-1-silafluorene in refluxing THF. The X-ray structure of 1,1-dipotassio-1-silafluorene (3b) shows C-C bond length equalization in the five-membered silole ring and C-C bond length alternation in the six-membered benzene rings, indicating aromatic delocalization of electrons in the silole ring. The downfield 29Si chemical shift at 29.0 ppm and theoretical calculations also support electron delocalization in the silole ring of 3b. Dianion salt 3b underwent nucleophilic reactions with Me3SiCl and EtBr to form the corresponding disubstituted products. Benzaldehyde underwent reductive coupling in the presence of 3b. Slow oxidation of 3b yielded 1,1′dipotassio-1,1′-bis(silafluorene) (16). The X-ray structure and 29Si chemical shift (-38.0 ppm) of 16 indicate localized negative charges at the silicon atoms and no aromatic character. Heating a DME/hexane solution of 3b in the presence of 18-crown-6 led to a novel diradical dianion salt.
- Liu,Stringfellow,Ballweg,Guzei,West
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- Manganese(III) acetate-mediated oxidative coupling of phenylhydrazines with benzene: A novel method for biaryl coupling
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The reaction of phenylhydrazines with benzene in the presence of manganese(III) acetate affords biaryls in good yields. The same reaction was carried out with similar oxidants, such as CoIII, CeIV and PbIV; among these oxidants MnIII acetate shows higher efficiency and selectivity.
- Demir,Reis,Oezguel-Karaaslan
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p. 3042 - 3045
(2007/10/03)
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- Enantioselective catalysis 113: New menthylphosphane ligands differing in steric and electronic properties
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A concept for bisphosphane ligands was developed, in which chirality is derived from the optically active (1R,3R,4S)-menthyl substituents in PMen2 groups and the backbone between the phosphorus units is varied (o-phenylene, 2,2'-biphenylene, 1,1'-ferrocenediyl); one of the two PMen2 groups was also replaced by a PPh2 unit. The synthesis and characterisation of seven new menthylphosphanes is described. Emphasis is put on the NMR assignment of the menthyl protons by two-dimensional methods and 13C-1H shift correlation. The ligands have been used in Rh and Ni complexes in several model reactions of enantiosclective catalysis giving optical inductions in the low to middle range.
- Brunner,Janura
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- ELECTRON SPIN RESONANCE STUDY OF PHOSPHORANYL RADICALS.PART II.INTRAMOLECULAR ELECTRON TRANSFER IN PHOSPHORANYL RADICALS. AN E.S.R. STUDY ON THE STEREOISOMERIZATION OF PHENYLPHOSPHORANYL RADICALS IN SOLUTION
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An electron spin resonance study on a series of phenylphosphoranyl radicals generated either by u.v. irradiation of solutions containing the corresponding P(III) or P(V) compounds and a dialkylperoxide, or by electrochemical reduction of the phosphonium salts, is reported.It is demonstrated, by careful examination of the phenylphosphoranyl radicals formed, that the initial procursor structure strongly defines the ultimate structure of the radicals detected.Furthermore, the transformation of a trigonal bipyramidal phenylphosphoranyl radical into its tetraherdal counterpart could actually be observed for the first time.This study therefore provides the prerequisites necessary for the isomerization process to take place. Key words: Phosphoranyl radicals ; stereoisomerization; ESR study; radical structure; TBP-e phenylphosphoranyl radicals; intramolecular electron transfer
- de Keijzer, A. E. H.,Buck, H. M.
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p. 201 - 210
(2007/10/02)
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- Vapour-phase Chemistry of Arenes. Part 13. Reactivity and Selectivity in the Gas-phase Reactions of Hydroxyl Radicals with Monosubstituted Benzenes at 563 K
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The reactions of hydroxyl radicals with benzene derivates C6H5Z (Z = H, Me, F, Cl, Br, I, CF3, or CN) have been studied in a flow reactor at 563 K in nitrogen, using the thermolysis of ButOOH as a source of .OH.Under these conditions there are two product-forming pathways.The major one involves hydrogen abstraction to give aryl radicals ZC6H4. (II) as the first step; depending on Z, its displacement to form phenol may also occur.Relative rates for hydrogen abstraction were determined in competition experiments using side-chain hydrogen abstraction from added toluene as a reference.This resulted in the order (for Z =): 1,8(Me), 1.0(H), 0.47(F), 0.29(Cl), 0.34(CF3), 0.20(CN), consonant with the electrophilic nature of .OH.The site selectivity of hydrogen abstractions was determined by scavenging part of the aryl radicals (II) with iodine.A Hammett plot, using ? constants for meta and para positions, led to ρ -1.0.The features of hydrogen abstraction by .OH are discussed and compared with those for the analogous reaction of Cl.The formation of phenol was found to decrease in importance in the order F, Cl, Br, and I.This result is rationalized on a thermochemical kinetic basis.
- Mulder, Peter,Louw, Robert
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p. 1167 - 1174
(2007/10/02)
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