- Rh-catalyzed reagent-free ring expansion of cyclobutenones and benzocyclobutenones
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Here we report a reagent-free rhodium-catalyzed ring-expansion reaction via C-C cleavage of cyclobutenones. A variety of poly-substituted cyclopentenones and 1-indanones can be synthesized from simple cyclobutenones and benzocyclobutenones. The reaction condition is near pH neutral without additional oxidants or reductants. The potential for developing a dynamic kinetic asymmetric transformation of this reaction has also been demonstrated. Further study supports the proposed pathway involving Rh-insertion into the cyclobutenone C-C bond, followed by β-hydrogen elimination, olefin insertion and reductive elimination.
- Chen, Peng-Hao,Sieber, Joshua,Senanayake, Chris H.,Dong, Guangbin
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- Geometry constrained N-(5,6,7-trihydroquinolin-8-ylidene)arylaminopalladium dichloride complexes: Catalytic behavior toward methyl acrylate (MA), methyl acrylate-co-norbornene (MA-co-NB) polymerization and heck coupling
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A new pair of plladium complexes (Pd4 and Pd5) ligated with constrained N-(5,6,7-trihydroquinolin-8-ylidene)arylamine ligands have been prepared and well characterized by 1H-, 13C-NMR and FTIR spectroscopies as well as elemental analysis. The molecular structure of Pd4 and Pd5 in solid state have also been determined by X-ray diffraction, showing slightly distorted square planar geometry around the palladium metal center. All complexes Pd1-Pd5 are revealed highly efficient catalyst in methyl acrylate (MA) polymerization as well as methyl acrylate/norbornene (MA/NB) copolymerization. In the case of MA polymerization, as high as 98.4% conversion with high molecular weight up to 6282 kg·mol-1 was achieved. Likewise, Pd3 complex has good capability to incorporate about 18% NB content into MA polymer chains. Furthermore, low catalyst loadings (0.002 mol %) of Pd4 or Pd5 are able to efficiently mediate the coupling of haloarenes with styrene affording up to 98% conversion.
- Zeng, Yanning,Mahmood, Qaiser,Liang, Tongling,Sun, Wen-Hua
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- Synthesis of pincer-type N-heterocyclic carbene palladium complexes with a hemilabile ligand and their application in cross-coupling catalysis
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Benzimidazolium salts containing both a neutral imine and a masked carboxylate functional group for potential metal chelation were prepared. Palladation of the ester-protected ligand afforded a N,C-bidentate carbene complex 4. Subsequent ester hydrolysis preserved the bidentate coordination mode and yielded complex 5 with a pending COOH group exclusively. However, when ester deprotection was carried out prior to metalation, the N,C,O-tridentate pincer-type coordinated palladium complex 7 was obtained. Proton-abstraction of the dangling COOH group in the bidentate ligand of complex 5 by treatment with a base led to the formation of the N,C,O-tridentate coordinated Pd system 7, and inversely, exposure of the tridentate bound Pd complex 7 with acid afforded the N,C-bidentate ligand coordination mode in complex 5, demonstrating hemilability of the oxygen donor site in the pincer ligand. All three palladium(II) complexes 4, 5, and 7 were evaluated in cross-coupling catalysis and revealed distinct activity differences that are dependent on the type of coupling (Suzuki vs. Heck) and the substrate (Ar-Br vs. Ar-Cl). These differences suggest that judicious choice of donor groups in pincer-type complexes is a viable strategy for catalyst optimization.
- Leigh, Vivienne,Ghattas, Wadih,Mueller-Bunz, Helge,Albrecht, Martin
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- Catalytic application of zwitterionic palladium complexes in Mizoroki-Heck reactions using ionic liquid as solvent
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New ligand precursors with different pendent alky chain length were obtained in a single step by reacting appropriate 1-alkyl-2-methyl-1H-imidazoles with chloroacetone in THF at 80°C overnight. Zwitterionic palladium complexes were prepared by reacting Pd
- Wang, Yi-Ping,Lee, Hon Man
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- METHODS OF ARENE ALKENYLATION
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The present disclosure provides for a rhodium-catalyzed oxidative arene alkenylation from arenes and styrenes to prepare stilbene and stilbene derivatives. For example, the present disclosure provides for method of making arenes or substituted arenes, in particular stilbene and stilbene derivatives, from a reaction of an optionally substituted arene and/or optionally substituted styrene. The reaction includes a Rh catalyst or Rh pre-catalyst material and an oxidant, where the Rh catalyst or Rh catalyst formed Rh pre-catalyst material selectively functionalizes CH bond on the arene compound (e.g., benzene or substituted benzene).
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Page/Page column 18; 21-22; 42-43; 49
(2021/11/26)
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- Synthesis of N-Heterocyclic Carbine Silver(I) and Palladium(II) Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C—C Coupling Reactions
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Two bis-imidazolium salts LH2·Cl2 and LH2·(PF6)2 with acylated piperazine linker and two N-heterocyclic carbene (NHC) silver(I) and palladium(II) complexes [L2Ag2](PF6)2 (1) and [L2Pd2Cl4] (2) were prepared. The crystal structures of LH2·Cl2 and 1 were confirmed by X-ray analysis. In 1, one 26-membered macrometallocycle was generated through two silver(I) ions and two bidentate ligands L. The catalytic activity of 2 was investigated in Sonogashira, Heck-Mizoroki and Suzuki-Miyaura reactions. The results displayed that these C—C coupling reactions can be smoothly carried out under the catalysis of 2.
- Liu, Qingxiang,Zhang, Xiantao,Zhao, Zhixiang,Li, Xinying,Zhang, Wei
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supporting information
p. 605 - 613
(2021/02/01)
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- Tandem Acceptorless Dehydrogenative Coupling-Decyanation under Nickel Catalysis
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The development of new catalytic processes based on abundantly available starting materials by cheap metals is always a fascinating task and marks an important transition in the chemical industry. Herein, a nickel-catalyzed acceptorless dehydrogenative coupling of alcohols with nitriles followed by decyanation of nitriles to access diversely substituted olefins is reported. This unprecedented C=C bond-forming methodology takes place in a tandem manner with the formation of formamide as a sole byproduct. The significant advantages of this strategy are the low-cost nickel catalyst, good functional group compatibility (ether, thioether, halo, cyano, ester, amino, N/O/S heterocycles; 43 examples), synthetic convenience, and high reaction selectivity and efficiency.
- Babu, Reshma,Balaraman, Ekambaram,Midya, Siba P.,Subaramanian, Murugan,Yadav, Vinita
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p. 7552 - 7562
(2021/06/28)
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- Stereospecific Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Cross-Coupling of Aryllithium with Vinyl Halides
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We present herein an efficient synthetic protocol involving iron-catalyzed cross-coupling of organolithium compounds with vinyl halides as key coupling partners. More than 30 examples were obtained with moderate to good yields and high stereoselectivities. The practicality of this method is evidenced by a gram-scale synthesis. In addition, a preliminary mechanistic investigation was also performed.
- Chen, Peng,Peng, Xiao-Shui,Wang, Zhi-Yong,Wong, Henry N. C.
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supporting information
p. 4385 - 4390
(2021/06/27)
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- Custom-Made Pyrene Photocatalyst-Promoted Desulfonylation of Arylethenyl Sulfones Using Green-Light-Emitting Diodes
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The Sonogashira coupling of 1,3,6,8-tetrabromopyrene with 4-[(-)-β-citronellyloxy]phenylethyne was employed to synthesize 1,3,6,8-tetra[4-(citronellyloxy)phenylethynyl]pyrene. The pyrene derivative catalyzed the reductive desulfonylation of ethenyl sulfones via visible-light irradiation (514 nm green light-emitting diodes) in the presence of i -Pr 2NEt. The β-citronellyloxy groups provided the sufficient solubility to the highly π-expanded pyrene catalyst, and their polar oxygen functionalities enabled the easy separation of the catalyst from the products via column chromatography.
- Watanabe, Hikaru,Nakajima, Kazuki,Ekuni, Kento,Edagawa, Ryota,Akagi, Yuta,Okuda, Yasuhiro,Wakamatsu, Kan,Orita, Akihiro
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p. 2984 - 2994
(2021/03/04)
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- Efficient photocatalytic chemoselective and stereoselective C-C bond formation over AuPd@N-rich carbon nitride
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Heterogeneous chemoselective or stereoselective C-C coupling reactions remain extremely challenging in traditional organic synthesis. Here, we constructed a AuPd@N-rich carbon nitride (NRCN) photocatalyst through simple ammonia solution heat treatment of carbon nitride and then AuPd NP loading. AuPd@NRCN exhibited extraordinary light color promoted catalytic performance in C-C bond formation under visible light in air. Surprisingly, both high chemoselectivity to unsymmetrical Ullmann biaryl products and satisfactory stereoselectivity to Z-type Heck reaction products could be achieved by changing the light source color. Various substrates exhibited great potential for the economical synthesis of unsymmetrical biaryl products and Z-type olefins. Efficient visible light promoted C-I bond activation accompanied with improved photocatalytic coupling reaction efficiency over AuPd@NRCN was verified firstly by in situ DRIFTS. Considering that the Ullmann cross-coupling reaction is a multi-photon reaction, the improved photocatalytic performance in the Ullmann cross-coupling reaction using a combination of light sources with different colors might be due to the activation of different substrates and/or steps requiring different energies, and the combination of the two energy sources was beneficial for improving the activation efficiency of different substrates and/or steps. The activation of iodobenzene and styrene in the Heck reaction with light was also beneficial to the formation of the stilbene product. The light color promoted chemoselectivity and stereoselectivity are expected to have profound impact on organic synthetic methodology improvement. This journal is
- Jiang, Heyan,Xu, Jie,Zhang, Sishi,Cheng, Hongmei,Zang, Cuicui,Bian, Fengxia
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p. 219 - 229
(2021/01/28)
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- Palladium Complexes with Phenoxy- And Amidate-Functionalized N-Heterocyclic Carbene Ligands Based on 3-Phenylimidazo[1,5- a]pyridine: Synthesis and Catalytic Application in Mizoroki-Heck Coupling Reactions with Ortho-Substituted Aryl Chlorides
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Mononuclear and tetranuclear palladium complexes with functionalized "abnormal"N-heterocyclic carbene (aNHC) ligands based on 3-phenylimidazo[1,5-a]pyridine were synthesized. All of the new complexes were structurally characterized by single-crystal X-ray diffraction studies. The new complexes were applied in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes in neat n-tetrabutylammonium bromide (TBAB). The mononuclear palladium complex with a tridentate phenoxy- and amidate-functionalized aNHC ligand displayed activity superior to that of the palladium complex with a bidentate amidate-functionalized aNHC ligand. The new tetranuclear complex with the tridentate ligand displayed the best activities, capable of the activation of deactivated aryl chlorides as substrates with a low Pd atom loading. Even challenging sterically demanding ortho-substituted aryl chlorides were successfully utilized as substrates. The studies revealed that the robustness of the catalyst precursor is crucial in delivering high catalytic activities. Also, the promising use of tetranuclear palladium complexes with functionalized aNHC ligands as the catalyst precursors in the Mizoroki-Heck coupling reaction in neat TBAB was demonstrated.
- Hung, Cheng-Hau,Zheng, Wei-Yuan,Lee, Hon Man
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p. 702 - 713
(2021/04/02)
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- New 1,2,3-triazole based bis- And trisphosphine ligands: Synthesis, transition metal chemistry and catalytic studies
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The syntheses and transition metal chemistry of triazole-based bis- and tris-phosphines, 5-(diphenylphosphanyl)-1-(2-(diphenylphosphanyl)phenyl)-4-phenyl-1H-1,2,3-triazole (2), 5-(diphenylphosphanyl)-4-(2-(diphenylphosphanyl)phenyl)-1-phenyl-1H-1,2,3-tria
- Balakrishna, Maravanji S.,Butcher, Ray J.,Kunchur, Harish S.,Namdeo, Pavan K.,Radhakrishna, Latchupatula
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p. 3434 - 3449
(2020/03/27)
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- Synthesis of Stilbenes by Rhodium-Catalyzed Aerobic Alkenylation of Arenes via C-H Activation
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Arene alkenylation is commonly achieved by late transition metal-mediated C(sp2)-C(sp2) cross-coupling, but this strategy typically requires prefunctionalized substrates (e.g., with halides or pseudohalides) and/or the presence of a directing group on the arene. Transition metal-mediated arene C-H activation and alkenylation offers an alternative method to functionalize arene substrates. Herein, we report a rhodium-catalyzed oxidative arene alkenylation from arenes and styrenes to prepare stilbene and stilbene derivatives. The reaction is successful with several functional groups on both the arene and the olefin including fluoride, chloride, trifluoromethyl, ester, nitro, acetate, cyanide, and ether groups. Reactions of monosubstituted arenes are selective for alkenylation at the meta and para positions, generally with approximately 2:1 selectivity, respectively. Resveratrol and (E)-1,2,3-trimethoxy-5-(4-methoxystyryl)benzene (DMU-212) are synthesized by this single-step approach in high yield. Comparison with palladium catalysis showed that rhodium catalysis is more selective for meta-functionalization for monosubstituted arenes and that the Rh catalysis has better tolerance of halogen groups.
- Jia, Xiaofan,Frye, Lucas I.,Zhu, Weihao,Gu, Shunyan,Gunnoe, T. Brent
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supporting information
p. 10534 - 10543
(2020/06/08)
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- cis-Selective Transfer Semihydrogenation of Alkynes by Merging Visible-Light Catalysis with Cobalt Catalysis
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Herein, the first example of visible-light-driven, cobalt-catalyzed transfer semihydrogenation of alkynes to alkenes is reported. It is carried out by using Ir[dF(CF3)ppy]2(dtbbpy)]PF6 as photosensitizer, CoBr2/n-Bu3P as proton-reducing catalyst, and i-Pr2NEt/AcOH as the hydrogen source. Under the established catalytic system, the semihydrogenation proceeds with Z as the major selectivity and with inhibition of over-reduction. Under mild reaction conditions, both internal and terminal alkynes, as well as reducible functional groups such as halogen, cyano, and ester, are tolerated. Preliminary mechanistic studies revealed the dual role of the photosensitizer in initiating the reaction via a single-electron transfer process and controlling the stereoselectivity via an energy transfer process. (Figure presented.).
- Ding, Hai-Xin,Guo, Wen-Jie,He, Yong-Qin,Song, Xian-Rong,Tian, Wan-Fa,Xiao, Qiang,Ye, Jing
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supporting information
(2020/02/05)
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- Stereoselective Chromium-Catalyzed Semi-Hydrogenation of Alkynes
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Chromium complexes have found very little applications as hydrogenation catalysts. Here, we report a Cr-catalyzed semi-hydrogenation of internal alkynes to the corresponding Z-alkenes with good stereocontrol (up to 99/1 for dialkyl alkynes). The catalyst comprises the commercial reagents chromium(III) acetylacetonate, Cr(acac)3, and diisobutylaluminium hydride, DIBAL?H, in THF. The semi-hydrogenation operates at mild conditions (1-5 bar H2, 30 °C).
- Gregori, Bernhard J.,Nowakowski, Michal,Schoch, Anke,P?llath, Simon,Zweck, Josef,Bauer, Matthias,Jacobi von Wangelin, Axel
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p. 5359 - 5363
(2020/09/03)
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- A Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Alkynes to (E)-Alkenes with Ethanol
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Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C5H4N)(C6H4)}RuCl(CO)(PPh3)2 (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.
- Chen, Dafa,Gong, Dawei,Hu, Bowen,Kong, Degong,Xia, Haiping,Yang, Weiwei
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- Diarylethene synthesis method without transition metal catalysis
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The invention discloses a diarylethene synthesis method without transition metal catalysis. The method comprises the following steps: a cinnamic acid derivative and aryl trifluoroborate are subjectedto a decarboxylation coupling reaction in a solvent under the action of an oxidizing agent, postprocessing is performed after the reaction, and diarylethene is obtained. K2S2O8 is adopted to promote acatalytic system in the synthetic method, and a free radical coupling reaction can be performed directly under the condition that no ligand, transition metal or alkali is added. The method has widersubstrate range and higher yield; the method is simple to operate, reaction conditions are mild, and large-scale application is facilitated.
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Paragraph 0036-0038; 0040
(2019/02/06)
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- Preparation method of palladium catalyzed 1,2-trans diaryl alkene
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The invention discloses a preparation method of palladium catalyzed 1,2-trans diaryl alkene. The method comprises the following steps that under the effects of catalysts, cocatalysts and alkali, arylacrylic acid and aromatic esters p-toluene sulfonate take decarboxylation coupling reaction in an organic solvent; after the reaction is finished, the 1,2-trans diaryl alkene is obtained through posttreatment. The method has the advantages that through C-O bond fracture, the operation is simple; a stable palladium catalyst with low cost is used; the substrate applicability is high; the harsh reaction conditions and the addition of strong alkali are not needed; the trans 1,2-diaryl alkene can be generated at high selectivity.
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Paragraph 0039-0042
(2019/06/11)
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- Mizoroki-Heck Cross-Coupling of Bromobenzenes with Styrenes: Another Example of Pd-Catalyzed Cross-Coupling with Potential Safety Hazards
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The potential safety hazards associated with the Mizoroki-Heck cross-coupling of bromobenzenes with styrenes were evaluated. The heat output from the reaction in various solvents was comparable in a variety of solvents; however, the rate of reaction was significantly faster in the presence of water. Thermal stability evaluation of the postreaction mixtures in DMSO and 3:1 DMSO/water by differential scanning calorimetry indicated that the onset temperatures of thermal decomposition were significantly lower than that of neat DMSO. Evaluation of the substrate scope revealed that the substitution pattern on the bromobenzene did not affect the heat output. The reaction rate of electron-deficient bromobenzenes was slower than that of the electron-rich bromobenzenes. In general, substituted styrenes afforded similar magnitudes of exotherms; however, the reaction rate of bromobenzene with 2-methylstyrene was significantly slower than the other studied styrenes. The predicted heat of reaction using the density functional theory method, B3LYP, was in good agreement with the experimental data. Such excellent agreement suggests that this calculation method can be used as a preliminary tool to predict heat of reaction and avoid exothermic reaction conditions. In many of the studied cases, the maximum temperature of a synthesis reaction was considerably higher than the solvent boiling point and thermal decomposition onset temperatures when the reaction was performed in DMSO or 3:1 DMSO/water. It is crucial to understand the thermal stability of the reaction mixture to design the process accordingly and ensure the reaction temperature is maintained below the onset temperature of decomposition to avoid potential runaway reactions.
- Yang, Qiang,Sane, Neeraj,Klosowski, Daniel,Lee, Melissa,Rosenthal, Tay,Wang, Nick X.,Wiensch, Eric
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p. 2148 - 2156
(2019/11/02)
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- Ultra-small and highly dispersed Pd nanoparticles inside the pores of ZIF-8: Sustainable approach to waste-minimized Mizoroki–Heck cross-coupling reaction based on reusable heterogeneous catalyst
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The rapid development of nanomaterials, particularly advanced hybrid nanoparticles, has made new opportunities for the design and fabrication of high-performance metal-based catalysts. However, generating metal nanoparticles of desired size without aggregation is an important challenge for enhancing the catalytic activity of metal nanoparticles supported in the host matrix. In this work, a hybrid nanoporous material, namely Pd nanoparticles@N-heterocyclic carbene@ZIF-8, with a high internal surface area was successfully prepared using a dispersed anionic sulfonated N-heterocyclic carbene–Pd(II) precursor inside the cavities of zeolitic imidazolate framework (ZIF-8) using an impregnation approach followed by reduction with NaBH4. The anionic sulfonated N-heterocyclic carbene was found to be a superb ligand for the stabilization of Pd nanoparticles in the pores of ZIF-8. The resulting system was applied to the Mizoroki–Heck cross-coupling reaction, in which the catalyst showed high catalytic activity under mild reaction conditions.
- Azad, Mohammad,Rostamizadeh, Shahnaz,Estiri, Hamid,Nouri, Fatemeh
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- Nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones with the liberation of H2
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A nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones to access various terminal and internal olefins with the liberation of hydrogen gas is reported.
- Landge, Vinod G.,Yadav, Vinita,Subaramanian, Murugan,Dangarh, Pragya,Balaraman, Ekambaram
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supporting information
p. 6130 - 6133
(2019/06/03)
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- Palladium-catalyzed decarboxylative coupling of α,β-unsaturated carboxylic acids with aryl tosylates
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We report a general method for selective cross-coupling of α,β-unsaturated carboxylic acids with aryl tosylates enabled by versatile Pd(II) complexes. This method features the general cross-coupling of ubiquitous α,β-unsaturated carboxylic acids by decarboxylation. The transformation is characterized by its operational simplicity, the use of inexpensive, air-stable Pd(II) catalysts, scalability and wide substrate scope. The reaction proceeds with high trans selectivity to furnish valuable (E)-1,2-diarylethenes.
- Zhang, Wei,Chen, Gairong,Wang, Kaikai,Xia, Ran
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- SBA-15/POSS-Imidazolium Hybrid as Catalytic Nanoreactor: the role of the Support in the Stabilization of Palladium Species for C?C Cross Coupling Reactions.
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Supported imidazolium modified polyhedral oligomeric silsesquioxanes (POSS) on SBA-15 have been used as platform for Pd(II) species. The so-obtained material was firstly characterized by means of TGA, solid state NMR, TEM, XPS, SAXS, porosimetry and ICP-OES and it was successfully tested as pre-catalyst in C?C cross couplings, namely Suzuki-Miyaura and Heck reactions. In both cases, the solid proved to be highly efficient and easily recoverable from the reaction mixture. The recyclability was verified for up to seven cycles without showing any activity decrease. Interestingly, only Pd(II) was detected in the reused catalyst in the Heck reaction. Therefore, the versatility of the material was investigated by using various aryl halides. Our palladium nanocomposite was able to promote both Suzuki and Heck reactions down to 0.0007 mol% showing outstanding turnover frequency (TOF) values of 114,286 and 32,381 h?1, respectively. Comparison with the palladium catalyst on SiO2-POSS-imidazolium support showed interesting differences in terms of stabilization of Pd species and recyclability. The excellent outcome of the reactions could be ascribed to the textural properties of the SBA-15 support and the presence of the imidazolium-POSS nanocage within the pores of SBA-15, that worked as a sort of nanoreactor. (Figure presented.).
- Calabrese, Carla,Campisciano, Vincenzo,Siragusa, Fabiana,Liotta, Leonarda F.,Aprile, Carmela,Gruttadauria, Michelangelo,Giacalone, Francesco
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p. 3758 - 3767
(2019/05/15)
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- Templating effect of carbon nanoforms on highly cross-linked imidazolium network: Catalytic activity of the resulting hybrids with Pd nanoparticles
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Two different carbon nanoforms (CNFs), namely multi-walled carbon nanotubes (MWCNTs) and carbon nanohorns (CNHs), have been chosen as support for the direct polymerization of a bis-vinylimidazolium salt. Transmission electron microscopy analyses revealed a templating effect of the CNFs on the growth of the polymeric network, which perfectly covers their whole surfaces creating a cylindrical or spherical coating for MWCNTs and CNHs, respectively. Subsequently, the CNFs-polyimidazolium have been used as stabilizers for Pd nanoparticles (Pd NPs), and the obtained materials have been characterized by means of analytical and spectroscopic techniques and then employed as easily recoverable and recyclable catalysts for Suzuki and Heck reactions. Quantitative conversions have been obtained in almost all the explored reactions, even employing low loading of catalyst (down to 0.007 mol%). Suzuki reactions were carried out in pure water under aerobic conditions. Both materials showed excellent activity and recyclability for the investigated C-C coupling reactions, with the CNHs-based material resulting slightly more active than the MWCNTs-based one due to a higher superficial exposure of Pd NPs.
- Campisciano, Vincenzo,Calabrese, Carla,Liotta, Leonarda Francesca,La Parola, Valeria,Spinella, Alberto,Aprile, Carmela,Gruttadauria, Michelangelo,Giacalone, Francesco
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- Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst
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The stereoselective hydrogenation of alkynes constitutes one of the key approaches for the construction of stereodefined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. This study concerns a simple catalyst comprised of the commercial chemicals iron(II) acetylacetonate and diisobutylaluminum hydride, which enables the Z-selective semihydrogenation of alkynes under near ambient conditions (1–3 bar H2, 30 °C, 5 mol % [Fe]). Neither an elaborate catalyst preparation nor addition of ligands is required. Mechanistic studies (kinetic poisoning, X-ray absorption spectroscopy, TEM) strongly indicate the operation of small iron clusters and particle catalysts.
- Gregori, Bernhard J.,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Fritsch, Lorena,Schoch, Roland,Bauer, Matthias,Jacobi von Wangelin, Axel
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p. 3864 - 3870
(2019/07/31)
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- Tetranuclear Palladium Complexes of Abnormal N-Heterocyclic Carbene Ligands and their Catalytic Activities in Mizoroki-Heck Coupling Reaction of Electron-Rich Aryl Chlorides
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Based on the ligand scaffold of an imidazolyl/benziimidazolyl moiety and a N-CH2C(=O)NHPh substituent, two series of ligand precursors with ortho hydroxy groups incorporated on the N-phenyl rings were prepared. The structural fine tuning of the ligand scaffold allowed the synthesis of tetranuclear palladium complexes with abnormal N-heterocyclic carbene (aNHC) ligands. For precursors with C2-methyl blocking groups, pyridine-assisted C?H bond activation led to the formation of mononuclear tridentate palladium aNHC complexes or tetranuclear complexes with tridentate CNO donors. Representative mononuclear and tetranuclearpalladium aNHC complexes were structurally characterized by X-ray diffraction studies, revealing very short Pd?C bond distances. The tetranuclear palladium aNHC complexes were very effective in catalyzing Mizoroki-Heck coupling reaction, and were capable of employing a range of aryl chlorides including deactivated substrates with low palladium loading of 0.2 mol%. (Figure presented.).
- Lee, Jhen-Yi,Su, Yong-Siang,Wang, Yu-Shan,Lee, Hon Man
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p. 4714 - 4726
(2019/09/03)
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- Synthesis and Characterization of C, C -Type Palladacycles and Their Catalytic Application in Mizoroki-Heck Coupling Reaction
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Two series of ligand precursors, based on imidazo[1,2-a]pyridine and C2-phenyl substituted imidazole moieties, were developed and synthesized in high yields, featuring an N-CH2(C=O)Ar substituent on the imidazole ring. Upon reacting with palladium acetate, both series of ligands underwent double C-H bond activations at the methylene and o-aryl carbon sites on the N-CH2(C=O)Ar substituent, yielding C,C-type palladacycles bearing five-membered chelate rings. A dimeric palladium complex with bridging bromides was obtained from the ligand precursor with the bromide anion, whereas an ionic palladium complex with two "throw away" pyridine ligands was formed with the precursor of the tetrafluoroborate anion. All complexes are air-stable and were characterized by 1H and 13C NMR spectroscopy and elemental analysis. The structures of three of the new complexes were further established by single-crystal X-ray diffraction studies. These complexes have been screened for catalyzing Mizoroki-Heck coupling reaction using ionic salt as solvent. The complex based on imidazo[1,2-a]pyridine, which has an electron-donating 4-methoxyphenyl ring on the ligand scaffold, was the most efficient catalyst, capable of using activated aryl chloride and sterically hindered aryl bromide as substrates. It was also successfully applied in the green process of one-pot Mizoroki-Heck coupling/trans-esterification reaction in molten ionic salt.
- Lo, Chi Hou,Lee, Hon Man
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p. 1150 - 1159
(2018/04/17)
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- Synthesis of a novel ZnO nanoplates supported hydrazone-based palladacycle as an effective and recyclable heterogeneous catalyst for the Mizoroki-Heck cross-coupling reaction
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A new hydrazone-based palladacycle complex was successfully prepared onto ZnO nanoplates support and was fully identified by using a variety of methods such as energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller analysis (BET), inductively coupled plasma technique (ICP), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The morphology of nanoplates support has been also confirmed by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). Furthermore, it was shown that ZnO nanoplates supported hydrazone-based palladacycle can act as a highly efficient heterogeneous catalyst for the Mizoroki-Heck cross-coupling reaction with excellent yields. The reaction was successfully carried out between aryl iodides, bromides or even aryl chlorides with a variety of olefins. Additionally, it is possible to isolate the catalyst from the reaction mixture and reused for eight sequential cycles without remarkable decrease in catalytic activity.
- Nouri, Fatemeh,Rostamizadeh, Shahnaz,Azad, Mohammad
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p. 664 - 673
(2017/12/15)
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- Catalytic activities of NHC-PdCl2 species based on functionalized tetradentate imidazolium salt in three types of C-C coupling reactions
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A functionalized tetradentate imidazolium salt 9,10-bis{di[2′-(N-ethylimidazolium-1-yl)ethyl]aminomethyl}anthracene tetrakis(hexafluorophosphate) (1) has been synthesized and characterized. The catalytic activity of the NHC-PdCl2 species formed by compound 1 and PdCl2 was tested in Suzuki-Miyaura, Heck-Mizoroki and Sonogashira reactions. The results showed that this catalytic system was effective for above three types of C-C coupling reactions.
- Liu, Qing-Xiang,Zhao, Dong-Xue,Wu, Hao,Zhao, Zhi-Xiang,Lv, Shi-Zhen
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- Enantioselective Synthesis of Indolines, Benzodihydrothiophenes, and Indanes by C?H Insertion of Donor/Donor Carbenes
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We employ a single catalyst/oxidant system to enable the asymmetric syntheses of indolines, benzodihydrothiophenes, and indanes by C?H insertion of donor/donor carbenes. This methodology enables the rapid construction of densely substituted five-membered rings that form the core of many drug targets and natural products. Furthermore, oxidation of hydrazones to the corresponding diazo compounds proceeds in situ, enabling a relatively facile one- or two-pot protocol in which isolation of potentially explosive diazo alkanes is avoided. Regioselectivity studies were performed to determine the impact of sterics and electronics in donor/donor metal carbene C?H insertions to form indolines. This methodology was applied to a variety of substrates in high yield, diastereomeric, and enantiomeric ratios and to the synthesis of a patented indane estrogen receptor agonist with anti-cancer activity.
- Souza, Lucas W.,Squitieri, Richard A.,Dimirjian, Christine A.,Hodur, Blanka M.,Nickerson, Leslie A.,Penrod, Corinne N.,Cordova, Jesus,Fettinger, James C.,Shaw, Jared T.
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supporting information
p. 15213 - 15216
(2018/10/31)
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- Fabrication of Pd/CuFe2O4 hybrid nanowires: A heterogeneous catalyst for Heck couplings
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The development of environmentally benign transformations is indispensable in organic synthesis. Herein, a hybrid heterogeneous catalyst, palladium(0) on copper ferrite nanowires, has been synthesized, characterized, and for the first time, employed in the Jeffrey Heck reaction between iodoarenes and allylic alcohols, and good to excellent yields have been obtained. In addition, the catalyst was found to be suitable for the usual Heck coupling. The nanocatalyst was recovered and reused up-to multiple runs without any noticeable loss of its catalytic activity.
- Lakshminarayana,Mahendar,Ghosal,Sreedhar,Satyanarayana,Subrahmanyam, Ch.
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p. 1646 - 1654
(2018/02/09)
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- Catalytic Chemoselective and Stereoselective Semihydrogenation of Alkynes to E-Alkenes Using the Combination of Pd Catalyst and ZnI2
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An efficient E-selective semihydrogenation of internal alkynes was developed under low dihydrogen pressure and low reaction temperature from commercially available reagents: Cl2Pd(PPh3)2, Zn0, and ZnI2. Kinetic studies and control experiments underline the significant role of ZnI2 in this process under H2 atmosphere, establishing that the transformation involves syn-hydrogenation followed by isomerization. This simple and easy-to-handle system provides a route to E-alkenes under mild conditions.
- Maazaoui, Radhouan,Abderrahim, Raoudha,Chemla, Fabrice,Ferreira, Franck,Perez-Luna, Alejandro,Jackowski, Olivier
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supporting information
p. 7544 - 7549
(2019/01/03)
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- Carbonyl–Olefin Cross-Metathesis Through a Visible-Light-Induced 1,3-Diol Formation and Fragmentation Sequence
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A visible-light-mediated approach to carbonyl–olefin cross-metathesis is described. Photoinduced hole catalysis was used to promote the formation of 1,3-diols from aldehydes and styrenes, which were then readily fragmented under acidic conditions to form the cross-metathesis products. The use of 1,3-diols as intermediates, rather than the energetically more demanding oxetanes, provides a new, orthogonal mechanistic strategy for carbonyl–olefin cross-metathesis. Furthermore, this approach does not require any metals, ligands, or additives, and provides the products with high levels of E selectivity. A mechanistic rationale is provided and supported by both theoretical calculations and experiments. Additionally, a practical synthesis of a new acridinium-based photocatalyst, including full characterization, is presented.
- Pitzer, Lena,Sandfort, Frederik,Strieth-Kalthoff, Felix,Glorius, Frank
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supporting information
p. 16219 - 16223
(2018/11/23)
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- Decarboxylative Arylation of α,β-Unsaturated Carboxylic Acids Using Aryl Triazenes by Copper/Ionic Liquid Combination in PEG-400
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A practical method for the construction of stilbene derivatives has been developed via catalytic cross-coupling of cinnamic acids with aryl triazenes. The methodology offers high stereoselectivity and is endowed with broad substrate scope, high yield, and significant functional group tolerance.
- Kumar, Saurabh,Kumar Pandey, Anand,Singh, Rahul,Nand Singh, Krishna
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supporting information
p. 5942 - 5946
(2018/11/10)
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- Direct Conversion of Alcohols into Alkenes by Dehydrogenative Coupling with Hydrazine/Hydrazone Catalyzed by Manganese
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We have developed unprecedented methods for the direct transformation of primary alcohols to alkenes in the presence of hydrazine, and for the synthesis of mixed alkenes by the reaction of alcohols with hydrazones. The reactions are catalyzed by a manganese pincer complex and proceed in absence of added base or hydrogen acceptors, liberating dihydrogen, dinitrogen, and water as the only byproducts. The proposed mechanism, based on preparation of proposed intermediates and control experiments, suggests that the transformation occurs through metal–ligand cooperative N?H activation of a hydrazone intermediate.
- Das, Uttam Kumar,Chakraborty, Subrata,Diskin-Posner, Yael,Milstein, David
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supporting information
p. 13444 - 13448
(2018/09/14)
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- O -Iodoxybenzoic acid mediated generation of aryl free radicals: Synthesis of stilbenes through C-C cross-coupling with β-nitrostyrenes
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The generation of an aryl free radicals in the presence of nitrostyrenes through a combination of aryl hydrazines and o-iodoxybenzoic acid led to the synthesis of stilbenes by forming a new carbon-carbon bond after subsequent elimination of a nitrosyl radical. The symmetrical and unsymmetrical stilbenes with excellent E-selectivity were synthesized in good yields, with advantages of broad substrate scope and transition metal free, mild reaction conditions, under an open atmosphere in a short reaction time. A free radical mediated mechanism was postulated and supported by radical trapping experiments. Application of the developed methodology is demonstrated through a simple, two step synthesis of resveratrol, a valuable stilbenoid for anticancer and neurological studies via its prodrug E-1,3-dimethoxy-5-(4-methoxystyryl)benzene.
- Wagh, Ganesh,Autade, Snehalata,Patil, Pravin C.,Akamanchi, Krishnacharya G.
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p. 3301 - 3309
(2018/03/06)
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- Prevention of Marine Biofouling Using the Natural Allelopathic Compound Batatasin-III and Synthetic Analogues
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The current study reports the first comprehensive evaluation of a class of allelopathic terrestrial natural products as antifoulants in a marine setting. To investigate the antifouling potential of the natural dihydrostilbene scaffold, a library of 22 syn
- Moodie, Lindon W. K.,Trepos, Rozenn,Cervin, Gunnar,Brathen, Kari Anne,Lindgard, Bente,Reiersen, Rigmor,Cahill, Patrick,Pavia, Henrik,Hellio, Claire,Svenson, Johan
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supporting information
p. 2001 - 2011
(2017/08/04)
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- Efficient Ni-catalyzed conversion of phenols protected with 2,4,6-trichloro-1,3,5-triazine (TCT) to olefins
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An efficient Ni(COD)2/dppf catalyzed olefination of Ar-O-TCT as synthetic equivalents of aryl halides is described. Activation of C-O bonds in phenols as readily available compounds was achieved with 2,4,6-trichloro-1,3,5-triazine (TCT). This method provides practical access to 1,2-disubstituted olefins in high yields and high functional group compatibility.
- Etemadi-Davan,Iranpoor
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supporting information
p. 12794 - 12797
(2017/12/06)
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- Olefination of N-Sulfinylimines under Mild Conditions
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A very simple and efficient diastereoselective synthesis of 1,2-disubstituted alkenes has been achieved under mild conditions. Sulfoxide stabilised N-sulfinylimines reacted with in-situ-generated phosphonate carbanions to give 1,2-disubtituted alkenes in good to excellent yields. Different aryl phosphonates reacted with a range of electronically diverse N-sulfinylimines to give alkenes with >99:1 E selectivity. The most important feature of this protocol is that the reaction can be carried out at room temperature with inexpensive sodium hydride as the most effective base to generate the reactive phosphonate carbanions, and producing the alkenes with E selectivity in up to 85 % isolated yield.
- Dhara, Shubhendu,Diesendruck, Charles E.
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p. 1184 - 1190
(2017/03/11)
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- Isolable C@Fe3O4 nanospheres supported cubical Pd nanoparticles as reusable catalysts for Stille and Mizoroki-Heck coupling reactions
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Cubical Pd nanoparticles incorporated magnetic nanospheres (Pd cNPs/C@Fe3O4) are found to be efficient catalysts for Stille and Mizoroki-Heck coupling reactions. A variety of aryl halides, including chlorides, are converted to biaryls and diphenylethenes with excellent yield and high TON. This immobilization of Pd cNPs on the surface C@Fe3O4 results in structurally stable catalytic sites. The observed enhanced catalytic activity is attributed to the high density of low-coordinated Pd {1?0?0} atoms present at the surface of the Pd cNPs/C@Fe3O4 catalyst. The advantages of the proposed catalytic system are its heterogeneity, high stability, absence of any toxic ligands, gram scale applicability, magnetic separability and consequent reusability.
- Kumar, Basuvaraj Suresh,Anbarasan, Rajagopal,Amali, Arlin Jose,Pitchumani, Kasi
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supporting information
p. 3276 - 3282
(2017/07/27)
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- Active Ruthenium (0) Nanoparticles Catalyzed Wittig-Type Olefination Reaction
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Abstract: Five different Ru metal precursors were reduced in imidazolium based ionic liquids under hydrogen atmosphere (4?bar) at 50 °C to obtain well-dispersed and stable Ru nanoparticles. Transmission electron microscopy (TEM) analysis confirmed size of well dispersed ionic liquid mediated Ru particles (Ru NPs) of 5?nm (±0.5) in diameter. These ruthenium nanoparticles (in ionic liquids) were used for Wittig type olefination reaction under mild reaction environment (70 °C and 1?h). The corresponding stilbenes were obtained in good yield with low-average selectivity. The proposed methodology is especially efficient for the synthesis of stilbenes as they were synthesized in the absence of any additive (as a hydrogen acceptor). The new catalytic system was also successfully applied for the synthesis of polymethoxylated and polyhydroxylated stilbenes, including resveratrol and DMU-212. Graphical Abstract: [Figure not available: see fulltext.]
- Srivastava, Vivek
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p. 693 - 703
(2017/03/08)
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- Unlocking Mizoroki–Heck-Type Reactions of Aryl Cyanides Using Transfer Hydrocyanation as a Turnover-Enabling Step
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A new transfer hydrofunctionalization strategy to turnover H-MII-X complexes has enabled both intra- and intermolecular Mizoroki–Heck (MH)-type reactions of aryl cyanides that are challenging to realize under traditional, basic conditions. Initially, a cascade carbonickelation/MH reaction of 2-cyanostyrenes was achieved using a key alkyne transfer hydrocyanation step. Mechanistic experiments supported the proposed catalytic cycle, including the turnover-enabling transfer hydrocyanation step. The reactivity was then extended to the intermolecular MH reaction of benzonitriles and styrenes.
- Fang, Xianjie,Yu, Peng,Prina Cerai, Gabriele,Morandi, Bill
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supporting information
p. 15629 - 15633
(2016/10/24)
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- Cyclodextrin-Grafted Silica-Supported Pd Nanoparticles: An Efficient and Versatile Catalyst for Ligand-Free C-C Coupling and Hydrogenation
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Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C-C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.
- Martina, Katia,Baricco, Francesca,Caporaso, Marina,Berlier, Gloria,Cravotto, Giancarlo
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p. 1176 - 1184
(2016/04/05)
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- TRPA1 channels as targets for resveratrol and related stilbenoids
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A series of twenty resveratrol analogues was synthesized and tested on TRPA1 and TRPV1 channels. None was able to significantly modulate TRPV1 channels. Conversely, most of them exhibited remarkably higher TRPA1 modulating activity than resveratrol. Optimal potency was observed with ortho monoxygenated stilbenes 6 and 17.
- Nalli, Marianna,Ortar, Giorgio,Moriello, Aniello Schiano,Morera, Enrico,Di Marzo, Vincenzo,De Petrocellis, Luciano
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p. 899 - 902
(2016/05/24)
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- Synthesis of stilbene derivatives via visible-light-induced cross-coupling of aryl diazonium salts with nitroalkenes using-NO2 as a leaving group
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The straightforward visible-light-induced synthesis of stilbene compounds via the cross-coupling of nitroalkenes and diazonium tetrafluoroborates under transition-metal-free conditions is described. The protocol uses green LEDs as light sources and eosin Y as an organophotoredox catalyst. Broad substrate scope and exclusive selectivity for the (E)-configuration of stilbenes are observed. This protocol proceeds via a radical pathway, with nitroalkenes serving as the radical acceptor, and the nitro group is cleaved during the process.
- Zhang, Na,Quan, Zheng-Jun,Zhang, Zhang,Da, Yu-Xia,Wang, Xi-Cun
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supporting information
p. 14234 - 14237
(2016/12/14)
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- Palladium-catalyzed Mizoroki-Heck-type reactions of [Ph2SRfn][OTf] with alkenes at room temperature
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The first Pd-catalyzed Mizoroki-Heck-type reaction of [Ph2SRfn][OTf] with alkenes is described. The reaction of [Ph2SRfn][OTf] (Rfn = CF3, CH2CF3) with alkenes in the presence of 10 mol% Pd[P(t-Bu)3]2 and TsOH at room temperature provided the corresponding phenylation products in good to high yields. The bases that benefit the traditional Mizoroki-Heck reactions severely inhibited the transformation with [Ph2SRfn][OTf], whereas acids significantly improved the reaction. This protocol supplies a new class of cross-coupling partners for Mizoroki-Heck-type reactions and gains important insights into the reactivity of phenylsulfonium salts either with or without fluorine-containing alkyl groups as the promising phenylation reagents in organic synthesis.
- Wang, Shi-Meng,Song, Hai-Xia,Wang, Xiao-Yan,Liu, Nan,Qin, Hua-Li,Zhang, Cheng-Pan
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supporting information
p. 11893 - 11896
(2016/10/09)
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- Well-defined palladium(0) complexes bearing N-heterocyclic carbene and phosphine moieties: Efficient catalytic applications in the Mizoroki-Heck reaction and direct C-H functionalization
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Two series of well-defined palladium(0) complexes with phosphine-functionalized N-heterocyclic carbene ligands were prepared. These complexes featured six- and seven-membered chelate rings in the two series. Among the seven-membered chelate complexes, those featuring the PCy2 moiety exhibited observable fluxional behavior on the NMR time scale, corresponding to the interchange between two sets of conformations. Most of these novel complexes were successfully structurally characterized by single-crystal X-ray diffraction studies. These two series of palladium(0) complexes were tested for their potential catalytic applications in two mechanistically distinct reactions, namely, Mizoroki-Heck coupling and direct C-H functionalization reactions. One of the six-membered chelate complexes was found to be an efficient pre-catalyst for mediating the coupling reactions between aryl chlorides and alkenes. The palladium(0) complex could also be effectively applied in the direct C-H functionalization reactions of aryl bromides with 1,2-dimethylimidazole.
- Lee, Jhen-Yi,Shen, Jiun-Shian,Tzeng, Ru-Jiun,Lu, I-Chen,Lii, Jenn-Huei,Hu, Ching-Han,Lee, Hon Man
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p. 10375 - 10388
(2016/07/06)
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- Z-Stereoselective Aza-Peterson Olefinations with Bis(trimethylsilane) Reagents and Sulfinyl Imines
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Highly stereoselective aza-Peterson olefinations from bench-stable α,α-bis(trimethylsilyl)toluene reagents and N-substituted imines have been achieved using TMSO-/Bu4N+ as Lewis base activator in THF. Remarkably, and for the first time, N-t-butanesulfinyl imines were utilized for the synthesis of Z-stilbenes with excellent selectivities, while N-aryl imines generated E-stilbenes under identical reaction conditions. The protocol proved general for numerous examples with low molecular weight byproducts formed. The origin of the Z-selectivity is proposed to be a result of diastereoselective addition to N-t-butanesulfinyl imines followed by syn-elimination of an in situ formed hypervalent silicate.
- Das, Manas,OShea, Donal F.
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supporting information
p. 336 - 339
(2016/02/03)
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- THERAPEUTIC AGENTS FOR SKIN DISEASES AND CONDITIONS
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The present invention relates to method(s) of treating a subject afflicted with a skin disease or condition, the method comprising administering to the subject or patient in need a composition comprising a therapeutically effective amount of a substituted cis or trans- stilbene or a stilbene hybrid. A method of treating or reducing the likelihood of a skin disease or condition in a patient is an additional embodiment of the present invention. Preferred pharmaceutical compositions of the invention include nanoemulsions comprising a therapeutically effective amount of a substituted cis or trans-stilbene or stilbene hybrid and at least one antibiotic.
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Page/Page column 36; 48-49; 52
(2015/06/18)
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- Synthesis, structure and catalysis of a NHC-Pd(II) complex based on a tetradentate mixed ligand
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Bis-benzimidazolium salt (S)-2,2′-bis[2′′-(N-picolyl-benzimidazoliumyl)ethoxy]-1,1′-binaphthyl hexafluorophosphate [(S)-LH2]·(PF6)2 and its NHC palladium(ii) complex [(S)-LPd](PF6)2 (1) have been prepared and characterized. Complex 1 is formed by one tetradentate mixed ligand (S)-L and one Pd(ii) ion, in which one 15-membered ring and two 6-membered rings are present. In this complex, intramolecular π-π interactions between naphthalene rings and benzimidazole rings are observed. Additionally, the catalytic activity of complex 1 in three types of C-C coupling reactions (Suzuki-Miyaura, Heck-Mizoroki and Sonogashira reactions) was investigated. The results show that complex 1 is an effective catalyst in these coupling reactions.
- Liu, Qing-Xiang,Cai, Kang-Qing,Zhao, Zhi-Xiang
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p. 85568 - 85578
(2015/11/03)
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- Rhodium-catalyzed oxidative decarbonylative Heck-type coupling of aromatic aldehydes with terminal alkenes
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A rhodium-catalyzed oxidative decarbonylative Heck-type coupling of aromatic aldehydes with terminal alkenes to afford 1,2-disubstituted alkenes with good regio- and E-selectivity is developed. This reaction employs readily available aromatic aldehydes as the aryl electrophile counterpart and relies on selected acyl chloride as the crucial additive to activate the rhodium catalyst precursor.
- Kang, Lei,Zhang, Feng,Ding, Lin-Ting,Yang, Luo
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p. 100452 - 100456
(2015/12/09)
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