- Catalytic activity of the titanocene complex with tolane in homogeneous hydrogenation of unsaturated hydrocarbons
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The titanocene complex with tolane, Cp2Ti(C2Ph2), is an effective catalyst for homogeneous hydrogenation of olefins and acetylenes at room temperature and atmospheric pressure.In the absence of unsaturated substrate, the complex readily reacts with molecu
- Shur, V.B.,Burlakow, V.V.,Vol'pin, M.E.
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- THE CHEMISTRY OF ORGANOBISMUTH REAGENTS PART XIII LIGAND COUPLING INDUCED BY Pd(0)
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Palladium zero converts triphenylbismuth quantitatively to diphenyl and metallic bismuth.many other derivatives of Bi(III) and Bi(V) are similarly transformed to diaryls in excellent yield.Similar reactions with triphenylantimony and with perphenyl lead derivatives suggest that number of non-transition metal elements should show similar behaviour.Acid chlorides also react under mild conditions with triphenylbismuth under catalysis by palladium(0) to furnish phenylketones in excellent yield (with respect to the triphenylbismuth).All three phenyls are transferred when a suitable excess of the acid chloride is used.Diaryl formation is a minor side reaction.
- Barton, Derek H. R.,Ozbalik, Nubar,Ramesh, Manian
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- Regiochemistry of the styrene insertion with CH2-bridged ansa-zirconocene-based catalysts
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Methylenebis(indenyl)zirconium dichloride substituted in C(3), activated by methylalumoxane, is able to give polystyrene and ethylene-styrene copolymers. In this study hydrooligomers, whose structure, determined by 13C NMR and GC-MS techniques, gives information about the regiochemistry and the stereochemistry of styrene insertion, have been purposefully prepared. The regiochemistry of the styrene insertion is related to the encumbrance of substituents in C(3). rac-[Methylene-(3-R-1-indenyl)2]ZrCl2 with R = H, CH3, or CH2CH3 induces a prevailingly secondary styrene insertion into the zirconium-carbon bond. With increasing the substituent's steric hindrance (R = CH(CH3)2), regiochemistry inversion occurs and the primary insertion becomes prevailing. The analysis of ethylene-styrene copolymers obtained in the presence of the different catalysts allows confirming the correlation between regiochemistry and comonomers' reactivity. Besides, also the stereospecificity can be evaluated from the structure of the hydrotrimers, when the insertion is primary. Whereas the isospecificity in the absence of substituents (secondary insertion) and in the presence of the tert-butyl substituent (primary insertion) is well-known, a surprising syndiospecificity is observed when the indenyl ligand bears the isopropyl substituent in C(3).
- Izzo, Lorella,Napoli, Mariagrazia,Oliva, Leone
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- Ligand-accelerated ortho -C-H alkylation of arylcarboxylic acids using alkyl boron reagents
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A protocol for the Pd(II)-catalyzed ortho-C-H alkylation of phenylacetic and benzoic acids using alkylboron reagents is disclosed. Monoprotected amino acid ligands (MPAA) were found to significantly promote reactivity. Both potassium alkyltrifluoroborates and alkylboronic acids were compatible coupling partners. The possibility of a radical alkyl transfer to Pd(II) was also investigated.
- Thuy-Boun, Peter S.,Villa, Giorgio,Dang, Devin,Richardson, Paul,Su, Shun,Yu, Jin-Quan
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- Unexpected formation of 1,4-diphenylbutylphosphinic acid from 1,4-diphenylbuta-1,3-diene and elemental phosphorus via the Trofimov–Gusarova reaction
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trans,trans-1,4-Diphenylbuta-1,3-diene reacts with elemental (red) phosphorus in the superbasic KOH / DMSO (H2O) system (120?°C, 3 h) to give, after acidic work-up, 1,4-diphenylbutylphosphinic acid in 48% yield.
- Artem'ev, Alexander V.,Sutyrina, Anastasiya O.,Matveeva, Elena A.,Albanov, Alexander I.,Klyba, Lyudmila V.
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- Synthesis and transformations of 4-phenylethynyl- and 4-styrylpyrazolo[5,1-c][1,2,4]triazines
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[Figure not available: see fulltext.] Rearrangements of 3-tert-butyl-8-methyl-4-phenylethynyl-1,4-dihydropyrazolo[5,1-c][1,2,4]triazine derivatives by the action of bases led to the formation of aromatic (E)- or (Z)-4-styryl-functionalized compounds. At t
- Ivanov, Sergey M.,Koltun, Denis S.
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- Microwave-assisted cross-coupling and hydrogenation chemistry by using heterogeneous transition-metal catalysts: An evaluation of the role of selective catalyst heating
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The concept of specific microwave effects in solid/liquid catalytic processes resulting from the selective heating of a microwave-absorbing heterogeneous transition-metal catalyst by using 2.45 GHz microwave irradiation was evaluated. As model transformations Ni/C-, Cu/C-, Pd/C-, and Pd/ Al 2O3-catalyzed carbon-carbon/ carbon-heteroatom cross-couplings and hydrogenation reactions were investigated. To probe the existence of specific microwave effects by means of selective catalyst heating in these transformations, control experiments comparing microwave dielectric heating and conventional thermal heating at the same reaction temperature were performed. Although the supported metal catalysts were experimentally found to be strongly microwave absorbing, for all chemistry examples investigated herein no differences in reaction rate or selectivity between microwave and conventional heating experiments under carefully controlled conditions were observed. This was true also for reactions that use low-absorbing or microwave transparent solvents, and was independent of the microwave absorbtivity of the catalyst support material. In the case of hydrogenation reactions, the stirring speed was found to be a critical factor on the mass transfer between gas and liquid phase, influencing the rate of the hydrogenation in both microwave and conventionally heated experiments.
- Irfan, Muhammed,Fuchs, Michael,Glasnov, Toma N.,Kappe, C. Oliver
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- Cycloalkane-based thermomorphic systems for organic electrochemistry: An application to Kolbe-coupling
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The discovery that cycloalkanes can form thermomorphic systems with typical polar organic solvents has led to the development of less-polar electrolyte solutions. Their mixing and separation can be regulated reversibly at a moderate temperature range. The phase switching temperature can be controlled by changing the solvent compositions. While biphasic conditions are maintained below the phase switching temperature, conductive monophasic conditions as less-polar electrolyte solutions are obtained above the phase switching temperature. After the electrochemical transformations, biphasic conditions are reconstructed below the phase switching temperature, facilitating the separation of cycloalkane where hydrophobic products or designed hydrophobic platforms are selectively partitioned. Several polar organic solvents, including acetonitrile, methanol, and pyridine, can be used in this system according to the requirement of the reactions.
- Okada, Yohei,Kamimura, Kazuya,Chiba, Kazuhiro
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- Detection of living anionic species in polymerization reactions using hyperpolarized NMR
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Intermediates during the anionic polymerization of styrene were observed using hyperpolarized NMR. Dissolution dynamic nuclear polarization (DNP) of monomers provides a sufficient signal-to-noise ratio for detection of 13C NMR signals in real t
- Lee, Youngbok,Heo, Gyu Seong,Zeng, Haifeng,Wooley, Karen L.,Hilty, Christian
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- Ni-catalyzed reductive homocoupling of unactivated alkyl bromides at room temperature and its synthetic application
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A room-temperature Ni-catalyzed reductive approach to homocoupling of unactivated primary, secondary, and tertiary alkyl bromides is described. The catalytic system can be easily generated from air-stable and cheap materials and demonstrates broad functional group tolerance, thus allowing facile access to useful dimeric triterpene and lignan-like molecules. Moreover, the dimerization of tertiary bromide 6 efficiently establishes sterically hindered vicinal quaternary carbons (C3a and C3a′), which is a key linkage of intriguing bispyrrolo[2,3-b]indoline alkaloids, thereby enabling us to complete the total syntheses of racemic chimonanthine (9) and folicanthine (10). In addition, this dimerization method can be expanded to the highly stereoselective synthesis of bisperhydrofuro[2,3-b]furan (5a) and the dimeric spiroketal 5b, signifying the involvement of possible radical species.
- Peng, Yu,Luo, Long,Yan, Chang-Song,Zhang, Jian-Jian,Wang, Ya-Wen
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- Homocoupling of alkyl-, alkenyl-, and arylboronic acids
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Alkyl-, alkenyl-, and arylboronic acids undergo Ag2O/CrCl2 mediated homocoupling in moderate to good yields under mild conditions. The general utility of this methodology is illustrated by an intramolecular annulation between sp and
- Falck,Mohapatra, Suchismita,Bondlela, Muralidhar,Venkataraman, Sylesh K.
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- Zinc-promoted reactions. 8. The effect of ring strain in the reduction of 1,2-dibenzoylcycloalkanes
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Ring cleavage was the main route in the Zn reduction of 1 in neat AcOH, while selective carbonyl reduction predominated in the presence of LiCl. The less strained 2 underwent only carbonyl reduction with Zn/AcOH. The Clemmensen reduction of both 1 and 2 resulted mainly in acyclic products. The unstrained 3 was fairly resistant towards reduction, and did not undergo ring cleavage.
- Di Vona, Maria Luisa,Luchetti, Luciana,Rosnati, Vittorio
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- From Esters to Ketones via a Photoredox-Assisted Reductive Acyl Cross-Coupling Strategy
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A method was developed for ketone synthesis via a photoredox-assisted reductive acyl cross-coupling (PARAC) using a nickel/photoredox dual-catalyzed cross-electrophile coupling of two different carboxylic acid esters. A variety of aryl, 1°, 2°, 3°-alkyl 2-pyridyl esters can act as acyl electrophiles while N-(acyloxy)phthalimides (NHPI esters) act as 1°, 2°, 3°-radical precursors. Our PARAC strategy provides an alternative and reliable way to synthesize various sterically congested 3°-3°, 3°-2°, and aryl-3° ketones under mild and highly unified conditions, which have been otherwise difficult to access. The combined experimental and computational studies identified a Ni0/NiI/NiIII pathway for ketone formation.
- Chen, Yukun,Li, Weirong,Luo, Yixin,Qi, Xiaotian,Xi, Xiaoxiang,Xu, Minghao,Yuan, Weiming,Zhao, Hongping,Zheng, Songlin
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supporting information
(2021/12/06)
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- Grignard reagent dictated copper(I) phosphines catalyzed reductive coupling of diazo compounds: The chemistry beyond carbene generation
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Copper-dppf catalyzed reductive coupling of diazo compounds through terminal nitrogen is reported. However, copper catalysts are known to produce carbene from diazo compounds; the reaction conditions played an important role in the formation of diazine over carbene generation. Several control experiments have been conducted to understand the reaction mechanism and found that the formation of a copper–Mg heterobimetallic complex would be responsible for the observed reactivity pattern. The reaction produced diazine as a reductive coupling product along with biphenyl as a by-product. All the synthesized diazines have been characterized fully by using analytical and spectroscopic techniques.
- Kuzhalmozhi Madarasi, Packirisamy,Sivasankar, Chinnappan
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- Asymmetric Synthesis of Enantiopure Pyrrolidines by C(sp3)?H Amination of Hydrocarbons
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The asymmetric synthesis of enantiopure pyrrolidines is reported via a streamlined strategy relying on two sequential C?H functionalizations of simple hydrocarbons. The first step is a regio- and stereoselective catalytic nitrene C?H insertion. Then, a su
- Darses, Benjamin,Dauban, Philippe,Lazib, Yanis,Retailleau, Pascal,Saget, Tanguy
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supporting information
p. 21708 - 21712
(2021/08/30)
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- Palladium nanoparticles stabilized by novel choline-based ionic liquids in glycerol applied in hydrogenation reactions
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Palladium nanoparticles stabilized by choline-based ionic liquids in glycerol were prepared from Pd(II) precursors by simply heating at 80 °C under argon; in this process, the water present in the ionic liquid was found to be responsible for the reduction of Pd(II) into zero-valent palladium species. Palladium nanoparticles were fully characterized in both liquid phase and solid state. The as-prepared metal nanoparticles exhibited remarkable catalytic activity in hydrogenation processes for a significant variety of functional groups (alkenes, alkynes, nitro derivatives, benzaldehydes, aromatic ketones).
- Garg, Garima,Foltran, Stéphanie,Favier, Isabelle,Pla, Daniel,Medina-González, Yaocihuatl,Gómez, Montserrat
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- HIGHLY SELECTIVE ELECTROCHEMICAL HYDROGENATION OF ALKYNES
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Disclosed are electrochemical methods to prepare an alkane or an alkene, such as a cis- alkene, from an alkyne, or an alkane from an alkene. The method utilizes an electrochemical cell having a cathode and an anode and a reactor.
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(2020/10/20)
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- CuPd Nanoparticles as a Robust Catalyst for Electrochemical Allylic Alkylation
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An efficient CuPd nanoparticle (NP) catalyst (3 nm CuPd NPs deposited on carbon support) is designed for catalyzing electrochemical allylic alkylation in water/isopropanol (1:1 v/v) and 0.2 m KHCO3 solution at room temperature. The Pd catalysis was Pd/Cu composition-dependent, and CuPd NPs with a Pd/Cu ratio close to one are the most efficient catalyst for the selective cross-coupling of alkyl halides and allylic halides to form C?C hydrocarbons with product yields reaching up to 99 %. This NP-catalyzed electrochemical allylic alkylation expands the synthetic scope of cross-coupling reactions and can be further extended to other organic reaction systems for developing green chemistry electrosynthesis methods.
- Guo, Xuefeng,Lin, Honghong,Muzzio, Michelle,Pang, Huan,Shen, Mengqi,Sun, Shouheng,Wei, Kecheng,Williard, Paul,Yin, Zhouyang,Yu, Chao
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supporting information
p. 15933 - 15936
(2020/07/04)
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- Chemoselective Hydrogenation of Alkynes to (Z) -Alkenes Using an Air-Stable Base Metal Catalyst
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A highly selective hydrogenation of alkynes using an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal-ligand cooperativity.
- Zubar, Viktoriia,Sklyaruk, Jan,Brzozowska, Aleksandra,Rueping, Magnus
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supporting information
p. 5423 - 5428
(2020/07/24)
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- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- Towards cleaner PolarClean: Efficient synthesis and extended applications of the polar aprotic solvent methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate
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As a result of recent efforts in green solvent selection, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, sold under the brand name Rhodiasolv PolarClean, has received considerable scientific and industrial attention as a possible non-toxic replacement
- Cseri, Levente,Szekely, Gyorgy
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supporting information
p. 4178 - 4188
(2019/08/07)
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- Photoredox-Catalysis-Modulated, Nickel-Catalyzed Divergent Difunctionalization of Ethylene
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Divergent synthesis that enables a catalytic reaction to selectively produce different products from common substrates will allow the charting of wider chemical space and the unveiling of distinct mechanistic paradigms. A common strategy for it employs different ligands to modulate organometallic catalysts. Dramatic developments in photocatalysis have enabled previously inaccessible transformations. In particular, photoredox catalysis modulates the oxidation state of transition-metal complexes, offering enormous opportunities for methodology development. Herein, we developed a photo-mediated divergent ethylene difunctionalization via modulating oxidation states of the nickel catalyst by using different photoredox catalysts. This work will inspire new perspectives for value-added chemical synthesis using ethylene as a feedstock and shed light on photoredox-catalyst-based divergent synthesis, which fundamentally differs from ligand-controlled transition-metal catalysis.Divergent synthesis represents a powerful strategy for directly accessing different molecular scaffolds originating from the same starting materials. Access to different end products via transition-metal catalysis is conventionally achieved by ligand control. We herein demonstrate the use of ethylene feedstock and commercially available aryl halides to accomplish the divergent synthesis of 1,2-diarylethanes, 1,4-diarylbutanes, or 2,3-diarylbutanes in a highly selective fashion through the synergistic combination of nickel and photoredox catalysis. Mechanistic studies suggest that the observed selectivity was due to different active states of Ni(I) and Ni(0) modulated by Ru- and Ir-based photoredox catalysts, respectively. The ability to access different organometallic oxidation states via photoredox catalysis promises to inspire new perspectives for synergistic transition-metal-catalyzed divergent synthesis.Functionalization of ethylene without polymerization is challenging under photo-irradiation conditions. We have demonstrated that the photo-transformation of ethylene can be controllable by merging photoredox and transition-metal catalysis. In our study, the use of different photoredox catalysts was able to modulate the oxidation state of the nickel catalyst. Through different oxidation states, the nickel-catalyzed couplings proceeded via distinct pathways to generate divergent ethylene difunctionalization products selectively from the same feedstock.
- Li, Jiesheng,Luo, Yixin,Cheo, Han Wen,Lan, Yu,Wu, Jie
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supporting information
p. 192 - 203
(2019/01/21)
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- Ni-Catalyzed Electrochemical Decarboxylative C-C Couplings in Batch and Continuous Flow
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An electrochemically driven, nickel-catalyzed reductive coupling of N-hydroxyphthalimide esters with aryl halides is reported. The reaction proceeds under mild conditions in a divided electrochemical cell and employs a tertiary amine as the reductant. This decarboxylative C(sp3)-C(sp2) bond-forming transformation exhibits excellent substrate generality and functional group compatibility. An operationally simple continuous-flow version of this transformation using a commercial electrochemical flow reactor represents a robust and scalable synthesis of value added coupling process.
- Li, Hui,Breen, Christopher P.,Seo, Hyowon,Jamison, Timothy F.,Fang, Yuan-Qing,Bio, Matthew M.
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p. 1338 - 1341
(2018/03/09)
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- Reactivity of the diphosphinodithio ligated nickel(0) complex toward alkyl halides and resultant nickel(i) and nickel(ii)-alkyl complexes
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Diphosphinodithio ligated complexes of nickel(0), nickel(i) and nickel(ii)-alkyl with a reactivity relevant to the C-C bond formation were described. Stoichiometric reactions of the nickel(0) complex, [(P2S2)Ni] ([1]0, P2S2 = (Ph2PC6H4CH2S)2(C2H4)), with alkyl halides (RX) such as C6H5CH2Br, C2H3CH2Br, C2H5I and (CH3)2CHI were investigated, from which the products were found to be highly dependent on the nature of RX used. Oxidative addition of C2H3CH2Br to [1]0 provides the stable Ni(ii)-alkyl complexes [1-allyl]+. The reaction of [1]0 with C6H5CH2Br proceeds through a radical pathway resulting in the formation of the nickel(i) complex [1]+ and an organic homo-coupled product 1,2-diphenylethane. Oxidative addition of C2H5I or (CH3)2CHI to [1]0 can be achieved but it competes with the halogen atom abstraction reaction as found for C6H5CH2Br. [1]0 was shown to be an active catalyst for the coupling reactions of primary halides and alkyl Grignard reagents.
- Zhang, Ailing,Wang, Congxiao,Lai, Xiaoyu,Zhai, Xiaofang,Pang, Maofu,Tung, Chen-Ho,Wang, Wenguang
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supporting information
p. 15757 - 15764
(2018/11/23)
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- High conversion of styrene, ethylene, and hydrogen to linear monoalkylbenzenes
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1-Alkylbenzenes as a precursor of surfactants, can be produced from ethylene, styrene, and hydrogen. These intermediates, lacking tertiary carbons, are environmentally more benign than commercial ones that bear the aromatic ring linked to an internal carbon of the aliphatic chain. The one-pot synthesis of highly linear 1-alkylbenzenes (LABs) through the homogeneous catalysis of olefin poly-insertion from cheap and largely available reagents can be carried out with a high turnover and selectivity. A purposely designed reactor that allows for the fine control of the three components feed, along with temperature, plays a key role in this achievement. A turnover of 194 g of LABs per mmol of catalyst per hour can be obtained with the simultaneous removal of polyethylene as a by-product.
- Lamparelli, David Hermann,Ricca, Antonio,Palma, Vincenzo,Oliva, Leone
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- A Copper-Catalyzed Reductive Defluorination of β-Trifluoromethylated Enones via Oxidative Homocoupling of Grignard Reagents
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An efficient copper-catalyzed reductive defluorination of β-trifluoromethylated enones via an oxidative homocoupling of Grignard reagents is reported. The reaction proceeded smoothly with a wide range of substrates, including the ones bearing aromatic heterocycles, such as furyl and thienyl ring systems in high yields (80-92%, except one example) under mild conditions. This provides a practical method for synthesis of gem-difluoroolefin ketones. It is also worth noting that this homocoupling process of Grignard reagents using β-trifluoromethylated enones as oxidizing reagents is effective for both the Csp2-Csp2 and Csp3-Csp3 bond formations, including for substrates whose β-hydride elimination of the corresponding transition metal alkyl complex is particularly facile, affording coupling products with high yields (83-95%), simultaneously.
- Wu, Xiaoting,Xie, Fang,Gridnev, Ilya D.,Zhang, Wanbin
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p. 1638 - 1642
(2018/03/23)
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- Inexpensive and rapid hydrogenation catalyst from CuSO4/CoCl2 — Chemoselective reduction of alkenes and alkynes in the presence of benzyl protecting groups
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The simple reduction of a number of alkenes and alkynes was performed with a typical reaction time of 20 min using a copper-cobalt catalytic system. The reduction did not cleave benzyl protecting groups which are usually vulnerable to catalytic hydrogenation reactions. The catalyst can be prepared in situ by reduction of the inexpensive precursor salts CuSO4 and CoCl2 with NaBH4. Sodium borohydride was also used as an easily handled hydrogen source for the catalytic reductions. No pressure, heating or inert atmosphere is required and purification/catalyst removal is achieved using extraction procedures, making this approach simple and efficient.
- Ficker, Mario,Svenningsen, S?ren W.,Larribeau, Thomas,Christensen, J?rn B.
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supporting information
p. 1125 - 1129
(2018/02/21)
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- Reductive Homocoupling of Organohalides Using Nickel(II) Chloride and Samarium Metal
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A homocoupling method for organohalides and organosulfonates promoted by samarium metal and HMPA, and catalyzed by NiCl2 has been developed. Various organohalides (benzyl, aryl, heterocyclic, alkenyl and alkyl halides), α-haloacetophenones, and phenyl organosulfonates were tolerated, and the reaction afforded coupling products with high efficiency. Excellent chemoselectivity was exhibited between halides and other groups, such as ?COOH, ?NO2, halogen, heterocyclic ring, ester, and ketone groups. The stereoselectivity suggested that the reaction mechanism might involve an organosamarium species.
- Liu, Yongjun,Xiao, Shuhuan,Qi, Yan,Du, Feng
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p. 673 - 678
(2017/03/22)
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- Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
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Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
- Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
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supporting information
p. 213 - 217
(2017/09/12)
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- A novel route to the synthesis of α,Ω-diphenylalkanes
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A novel route to the synthesis of α,ω-diphenylalkanes is reported. Toluene was metalated in the benzylic position by n-butyllithium with THF as an activating reagent, and then directly reacted with α,ω-dichloroalkanes to obtain the target product. This process provides a facile and efficient route to the synthesis of α,Ω-diphenylalkanes.
- Chen, Hui,Chen, Yancai,Zhang, Yinlong,Yang, Zhenqiang,Li, Ji,Yang, Ruina,Wang, Wenxin
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p. 473 - 474
(2017/08/18)
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- Cobalt-Catalyzed Csp3?Csp3Homocoupling
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An efficient and easy method for Csp3?Csp3homocoupling was developed using cobalt bromide as catalyst. A series of functionalized alkyl bromides and alkyl chlorides were coupled in high yields under mild conditions. This reaction seems to involve a radical intermediate. (Figure presented.).
- Cai, Yingxiao,Qian, Xin,Gosmini, Corinne
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supporting information
p. 2427 - 2430
(2016/08/16)
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- Redox-Active Esters in Fe-Catalyzed C-C Coupling
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Cross-couplings of alkyl halides and organometallic species based on single electron transfer using Ni and Fe catalyst systems have been studied extensively, and separately, for decades. Here we demonstrate the first couplings of redox-active esters (both isolated and derived in situ from carboxylic acids) with organozinc and organomagnesium species using an Fe-based catalyst system originally developed for alkyl halides. This work is placed in context by showing a direct comparison with a Ni catalyst for >40 examples spanning a range of primary, secondary, and tertiary substrates. This new C-C coupling is scalable and sustainable, and it exhibits a number of clear advantages in several cases over its Ni-based counterpart.
- Toriyama, Fumihiko,Cornella, Josep,Wimmer, Laurin,Chen, Tie-Gen,Dixon, Darryl D.,Creech, Gardner,Baran, Phil S.
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supporting information
p. 11132 - 11135
(2016/10/12)
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- Phosphido- and Amidozirconocene Cation-Based Frustrated Lewis Pair Chemistry
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Methyl abstraction from neutral [Cp2ZrMe(ERR)] complexes 1 (E = N, P; R, R'; = alkyl, aryl) with either B(C6F5)3 or [Ph3C][B(C6F5)4] results in the formation of [Cp2Zr(ERR′)][X] complexes 2 (X- = MeB(C6F5)3-, B(C6F5)4-). The X-ray structure of amido complexes [Cp2Zr(NPh2)][MeB(C6F5)3] (2d) and [Cp2Zr(NtBuAr)][B(C6F5)4] (2e′, Ar = 3,5-C6H3(CH3)2) is reported, showing a sterically dependent Zr/N' interaction. Complexes 2 catalyze the hydrogenation of electron-rich olefins and alkynes under mild conditions (room temperature, 1.5 bar H2). Complex 2e binds CO2, giving [Cp2Zr(CO2)(NtBuAr)]2[MeB(C6F5)3]2 (3e). Amido complex 2d reacts with benzaldehyde yielding [Cp2Zr(OCH2Ph)((OC)PhNPh2)][MeB(C6F5)3] (7d). Phosphido complex [Cp2Zr(PCy2)][MeB(C6F5)3] (2a) reacts with diphenylacetylene to yield frustrated Lewis pair [Cp2Zr(PhCCPh)(PCy2)][MeB(C6F5)3] (8a) which further reacts with a range of carbonyl substrates.
- Normand, Adrien T.,Daniliuc, Constantin G.,Wibbeling, Birgit,Kehr, Gerald,Le Gendre, Pierre,Erker, Gerhard
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supporting information
p. 10796 - 10808
(2015/09/28)
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- Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides
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The direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)-C(sp3) cross-coupling showed excellent functional-group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)-C(sp3) bonds. Zinc and you'll miss it. Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with alkyl halides proceeded rapidly at ambient temperature without a coordinating ethereal solvent or an added catalyst (see scheme). This versatile, operationally simple approach to C(sp2)-C(sp3) bond formation enables the expedient construction of a diverse array of carbon-based structural motifs.
- Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
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supporting information
p. 5688 - 5692
(2015/05/19)
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- Homocoupling of aryl halides promoted by an NiCl2/bpy/Mg system in DMF
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Homocoupling of aryl halides (2 ArX → Ar-Ar) promoted by NiCl 2/2,2-bipyridine (bpy)/Mg mixtures in DMF has been studied. Mixtures of NiCl2, bpy and Mg in DMF promoted homocoupling of aryl halides such as phenyl bromide and p-tolyl bromide to give the coupling products in good (e.g. approximately 60-75%) yields, and the homocoupling products were easily isolated from the reaction mixtures. Application of this homocoupling to dibromo-aromatic compounds (Br-arylene-Br: 2,5-dibromopyridine, 2,7-dibromo-9.9-dioctylfluorene and 2,7-dibromo-9,10-dioctyl-9,10- dihydrophenanthrene) gave the corresponding π-conjugated polymers, -(arylene)n-, in good yields. Organometallic processes for the homocoupling are discussed. Copyright
- Yamamoto, Takakazu
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p. 598 - 604
(2014/08/05)
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- Mesoporous organic Pd-containing catalysts for the selective hydrogenation of conjugated hydrocarbons
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Palladium catalysts supported on ordered organic mesoporous polymers were synthesized. The catalysts are characterized by the narrow size distribution of palladium nanoparticles with an average particle size of 2.2-5.2 nm. They demonstrate high catalytic activity and selectivity in phenylacetylene hydrogenation (896-2590 min-1, selectivity 89-98%). High activity and selectivity for alkenes are observed in the hydrogenation of conjugated dienes (for isoprene, TOF = 1850-5000 min-1, selectivity 99%; for 2,5-dimethyl-2,4-hexadiene, TOF = = 1294-2400 min-1, selectivity 100%; for 1,4-diphenyl-1,3-butadiene, TOF = 14-22 min-1, selectivity 7-16%). A dependence of the selectivity on the nature of the support and substrate was found for the hydrogenation of 1,4-diphenyl-1,3-butadiene.
- Karakhanov,Maksimov,Aksenov,Kuznetsov,Filippova,Kardashev,Volkov
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p. 1710 - 1716
(2015/05/20)
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- Copper-catalyzed oxidative homo- and cross-coupling of grignard reagents using diaziridinone
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Transition-metal-catalyzed cross-coupling reactions are among the most powerful synthetic transformations. This paper describes an efficient copper-catalyzed homo- and cross-coupling of Grignard reagents with di-tert-butyldiaziridinone as oxidant under mild conditions, giving the coupling products in good to excellent yields. The reaction process has a broad substrate scope and is also effective for the C(sp)-C(sp3) coupling.
- Zhu, Yingguang,Xiong, Tao,Han, Wenyong,Shi, Yian
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supporting information
p. 6144 - 6147
(2015/01/09)
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- Dilithium tetrachlorocuprate(II) catalyzed oxidative homocoupling of functionalized grignard reagents
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An efficient procedure is described for the oxidative homocoupling of functionalized Grignard reagents using a catalytic amount of dilithium tetrachlorocuprate(II) (CuLi2Cl4) in the presence of pure oxygen gas. This method is applied successfully to a variety of aryl, heteroaryl, alkyl, alkenyl and alkynyl halides, which are converted into the corresponding homocoupled products in good to excellent yields. Georg Thieme Verlag Stuttgart · New York.
- Hua, Si-Kai,Hu, Qiu-Peng,Ren, Jiangmeng,Zeng, Bu-Bing
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p. 518 - 526
(2013/03/29)
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- Iron-catalysed alkene hydrogenation and reductive cross-coupling using a bench-stable iron(II) pre-catalyst
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Operationally simple, iron-catalysed hydrogenation and reductive cross-coupling protocols have been developed using a bench-stable iron(ii) pre-catalyst. The hydrogenation of 18 alkenes (50-99%) and reductive cross-coupling of vinyl halides with aryl- and alkyl Grignard reagents (8 examples, 18-99%) is reported using 3 mol% pre-catalyst and hydrogen as stoichiometric reductant (1-50 bar).
- Frank, Dominik J.,Guiet, Lea,Kaeslin, Alexander,Murphy, Elliot,Thomas, Stephen P.
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p. 25698 - 25701
(2013/12/04)
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- Suzuki-miyaura cross-coupling reactions of unactivated alkyl halides catalyzed by a nickel pincer complex
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A nickel(II) pincer complex, [(MeN2N)Ni-Cl], was used to catalyze alkyl-alkyl and alkyl-aryl Suzuki-Miyaura coupling reactions of unactivated alkyl halides. The coupling of 9-alkyl-9-borabicyclo[3.3.1]nonane and 9-phenyl-9-borabicyclo[3.3.1]nonane reagents with alkyl halides was achieved in modest to good yields. The reactions tolerated a variety of useful functional groups including ester, ether, furan, thioether, acetal, and Boc groups. Georg Thieme Verlag Stuttgart, New York.
- Di Franco, Thomas,Boutin, Nicolas,Hu, Xile
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p. 2949 - 2958
(2013/11/06)
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- Construction of quaternary carbon centers by using substitution of γ,γ-disubstituted secondary allylic picolinates with alkylcopper reagents
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ZnI2 was found to promote regio- and stereoselective substitution of γ,γ-disubstituted secondary allylic picolinates with alkylcopper reagents derived from alkyl-MgBr and CuBr·Me2S in a 2:1 ratio to furnish quaternary carbon centers in good yields. Alkyl groups delivered efficiently were the primary, secondary, and benzyl classes such as Me, Et, Bu, C16H33, Ph(CH2)2, Ph(CH2)3, c-C6H11, and Bn. As an application, allylic picolinates with the (E)- or (Z)-olefin afforded quaternary carbon centers that are the enantiomers of each other.
- Feng, Chao,Kaneko, Yuki,Kobayashi, Yuichi
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p. 4629 - 4632
(2013/08/23)
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- Oxidative coupling reactions of grignard reagents with nitrous oxide
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Catalysis with laughing gas: N2O in combination with transition-metal catalysts allow the oxidative homo- and cross-coupling of Grignard reagents. The reactions can be performed under mild conditions despite the inert character of N2O. Copyright
- Kiefer, Gregor,Jeanbourquin, Loic,Severin, Kay
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supporting information
p. 6302 - 6305
(2013/07/19)
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- Active-alkali metal promoted reductive desulfurization of dibenzothiophene and its hindered analogues
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Dibenzothiophene and some related organosulfur compounds are efficiently reductively desulfurized under mild reaction conditions, with Na and/or Li metal in the presence of a catalytic amount of tetraphenylethylene in THF at room temperature. This simple methodology was applied to the synthesis of several substituted biphenyls, thus realizing a connection between the directing properties of the sulfur atom of dibenzothiophene and the efficiency of 1,2-dianions of tetraphenylethane as homogenous electron transfer reagents.
- Pittalis, Mario,Azzena, Ugo,Pisano, Luisa
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p. 207 - 211
(2013/01/15)
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- Design, synthesis, theoretical calculations and biological evaluation of new non-symmetrical choline kinase inhibitors
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Inhibition of Choline Kinase (ChoK) has been reported as a therapeutical target in the treatment of some kinds of tumor. In this paper, the design and synthesis of new non-symmetrical monocationic ChoK inhibitors is described, bearing a cationic head and an adenine moiety connected by linkers of different lengths. Docking studies indicate that the cationic head of these compounds could be inserted into the choline binding site of the enzyme, while the adenine moiety could be stabilized into the ATP binding site. Docking studies also support the difference of activity of the synthesized compounds, which depends on both the substituent at position 4 of the cationic head and the linker length, being dimethylamine and 1,4-diphenylbutane respectively, the most appropriate ones. Compounds 14 (IC50 = 10.70 ± 0.40 μM) and 17 (IC50 = 6.21 ± 0.97 μM) are the most potent ChoK inhibitors and suitable for further modification with a view to obtain more potent antitumor compounds.
- Rubio-Ruíz, Belén,Conejo-García, Ana,Ríos-Marco, Pablo,Carrasco-Jiménez, María Paz,Segovia, Josefa,Marco, Carmen,Gallo, Miguel A.,Espinosa, Antonio,Entrena, Antonio
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body text
p. 154 - 162
(2012/07/14)
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- C-C coupling promoted by a NiCl2/bpy/Mg system in DMF and its application to dehalogenative polycondensation
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A mixture of NiCl2, 2,2′-bipyridine (bpy), and Mg in DMF promoted dehalogenative homocoupling of RX (e.g., bromobenzene and p-tolyl bromide) efficiently. This basic coupling reaction was applied for polycondensation of dihaloorganic compounds, XR′ X, to give poly(9,9-dioctylfluorene-2,7-diyl), poly(9,10-dioctyl-9,10-dihydrophenanthrene- 2,7-diyl), and poly-(pyridine-2,5-diyl).
- Yamamoto, Takakazu
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supporting information
p. 1422 - 1424
(2013/01/15)
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- Cross coupling reactions of multiple CCl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex
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The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6- diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp 3-sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20 min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4 mol% and turnover frequency (TOF) as high as 724 h-1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.
- Gartia, Yashraj,Nasini, Udaya Bhasker,Ghosh, Anindya,Biswas, Abhijit,Stadler, Matthew
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p. 322 - 327,6
(2020/07/30)
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- Enyne chlorides: Substrates for copper-catalyzed asymmetric allylic alkylation
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A select few: Several prochiral enyne chlorides were employed as substrates in the title reaction using Grignard reagents as the alkylation reagents (see scheme; CuTC=copper(I) thiophenecarboxylate). Excellent 1,3 substitution regioselectivities and good to excellent enantioselectivities were obtained. The substrate scope is additionally extended to diene chlorides. Copyright
- Li, Hailing,Alexakis, Alexandre
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supporting information; experimental part
p. 1055 - 1058
(2012/04/05)
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- Iron-catalysed, hydride-mediated reductive cross-coupling of vinyl halides and Grignard reagents
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An iron-catalysed, hydride-mediated reductive cross-coupling reaction has been developed for the preparation of alkanes. Using a bench-stable iron(ii) pre-catalyst, reductive cross-coupling of vinyl iodides, bromides and chlorides with aryl- and alkyl Grignard reagents successfully gave the products of formal sp3-sp3 cross-coupling reactions.
- Le Bailly, Bryden A. F.,Greenhalgh, Mark D.,Thomas, Stephen P.
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supporting information; experimental part
p. 1580 - 1582
(2012/03/26)
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- Homodimeric bis-quaternary heterocyclic ammonium salts as potent acetyl- and butyrylcholinesterase inhibitors: A systematic investigation of the influence of linker and cationic heads over affinity and selectivity
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A molecular library of quaternary ammonium salts (QASs), mainly composed of symmetrical bis-quaternary heterocyclic bromides exhibiting choline kinase (ChoK) inhibitory activity, were evaluated for their ability to inhibit acetyl- and butyrylcholinesterase (AChE and BChE, respectively). The molecular framework of QASs consisted of two positively charged heteroaromatic (pyridinium or quinolinium) or sterically hindered aliphatic (quinuclidinium) nitrogen rings kept at an appropriate distance by lipophilic rigid or semirigid linkers. Many homodimeric QASs showed AChE and BChE inhibitory potency in the nanomolar range along with a low enzymatic selectivity. Computational studies on AChE, BChE, and ChoK allowed identification of the key molecular determinants for high affinity and selectivity over either one of the three enzymes and guided the design of a hybrid bis-QAS (56) exhibiting the highest AChE affinity (IC50 = 15 nM) and selectivity over BChE and ChoK (SI = 50 and 562, respectively) and a promising pharmacological potential in myasthenia gravis and neuromuscular blockade.
- Conejo-García, Ana,Pisani, Leonardo,Del Carmen Nú?ez, Maria,Catto, Marco,Nicolotti, Orazio,Leonetti, Francesco,Campos, Joaquín M.,Gallo, Miguel A.,Espinosa, Antonio,Carotti, Angelo
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body text
p. 2627 - 2645
(2011/06/21)
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- Exceptionally high decarboxylation rate of a primary aliphatic acyloxy radical determined by radical product yield analysis and quantitative 1H-CIDNP spectroscopy
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Symmetrical (RCO2CO2R; R=XCH2CH 2) and asymmetrical (RCO2CO2R′; R=C 9H19CH2CH2, R′=CH3 or m-ClC6H4) primary diacyl peroxides were thermally decomposed under different conditions to analyze the decarboxylation rates of the thermally generated acyloxy radicals. Quantitative models of the geminate product yields, and qualitative and quantitative 1H-CIDNP spectroscopy were used to obtain the decarboxylation rate estimates. Results reported here suggest that, unlike short chain acyloxy radicals such as propanoyloxyl, long chain acyloxy radicals possess the highest decarboxylation rates of all known acyloxy radicals, estimated at (0.5-1.5)× 10 12s-1 between 80 and 140°C. Given the nature of the dissociative state of acyloxy radicals, such rates appear to be the result of destabilization of the former by the steric bulk of the long chain substituents. Additionally, the rate of this order of magnitude suggests a nearly concerted decarboxylation of primary diacyl peroxides. Copyright
- Fraind, Alicia,Turncliff, Ryan,Fox, Teri,Sodano, Justin,Ryzhkov, Lev R.
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scheme or table
p. 809 - 820
(2012/06/29)
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- Pd nanoparticles dispersed on solid supports: Synthesis, characterization and catalytic activity on selective hydrogenation of olefins in aqueous media
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Two types of Pd nanoparticle catalysts were prepared having 2-4 nm particle size using silica gel and porous polymer beads as solid supports. 2-Pyridinecarboxaldehyde ligand was anchored on commercially available 3-aminopropyl-functionalized silica gel followed by Pd metal dispersion. Bead-shaped cross-linked poly(4-vinylpyridine-co-styrene) gel was prepared by an emulsifier-free emulsion polymerization of 4-vinylpyridine, styrene and divinylbenzene in the presence of ammonium persulfate and subsequently dispersing the Pd metal on the synthesized polymer. These catalysts were characterized by SEM, TEM and ICP techiniques with respect to appearance, size and possible leaching out, respectively. Furthermore, the reactivity of these catalysts was tested on hydrogenation of various α,β-unsaturated carbonyl compounds using aqueous solvent under a hydrogen balloon (1 atm). The results showed that the Pd dispersed on silica was a more efficient catalyst than Pd dispersed on polymer and the former could be recycled more than 10 times without considerable loss in activity. Copyright
- Lim, Minkyung,De Castro, Kathlia A.,Oh, Seungchan,Lee, Kangsuk,Chang, Young-Wook,Kim, Hokun,Rhee, Hakjune
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scheme or table
p. 1 - 8
(2011/09/14)
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- A structure-activity study of Ni-catalyzed alkyl-alkyl kumada coupling. Improved catalysts for coupling of secondary alkyl halides
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A structureactivity study was carried out for Ni catalyzed alkylalkyl Kumada-type cross coupling reactions. A series of new nickel(II) complexes including those with tridentate pincer bis(amino)amide ligands (RN2N) and those with bidentate mixed amino-amide ligands (RNN) were synthesized and structurally characterized. The coordination geometries of these complexes range from square planar, tetrahedral, to square pyramidal. The complexes had been examined as precatalysts for cross coupling of nonactivated alkyl halides, particularly secondary alkyl iodides, with alkyl Grignard reagents. Comparison was made to the results obtained with the previously reported Ni pincer complex [( MeN2N)NiCl]. A transmetalation site in the precatalysts is necessary for the catalysis. The coordination geometries and spin-states of the precatalysts have a small or no influence. The work led to the discovery of several well-defined Ni catalysts that are significantly more active and efficient than the pincer complex [(MeN2N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [(HNN)Ni(PPh3)Cl] and [(HNN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni center during catalysis. The activation of alkyl halides was shown to proceed via a radical mechanism.
- Ren, Peng,Vechorkin, Oleg,Von Allmen, Kim,Scopelliti, Rosario,Hu, Xile
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supporting information; experimental part
p. 7084 - 7095
(2011/06/26)
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- Sequential reactions directed by core/shell catalytic reactors
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Millimeter-sized reactor particles made of permeable polymer doped with catalysts arranged in a core/shell fashion direct sequences of chemical reactions (e.g., alkyne coupling followed by hydrogenation or hydrosilylation followed by hydrogenation). Spati
- Wei, Yanhu,Soh, Siowling,Apodaca, Mario M.,Kim, Jiwon,Grzybowski, Bartosz A.
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body text
p. 857 - 863
(2010/10/03)
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- Nickel-catalyzed, sodium iodide-promoted reductive dimerization of alkyl halides, alkyl pseudohalides, and allylic acetates
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The first general method for the reductive dimerization of alkyl halides, alkyl mesylates, alkyl trifluoroacetates, and allylic acetates is reported which proceeds with low catalyst loading (0.5 to 5 mol%), generally high yields (80% ave yield), and good functional-group tolerance.
- Prinsell, Michael R.,Everson, Daniel A.,Weix, Daniel J.
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supporting information; experimental part
p. 5743 - 5745
(2010/09/18)
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- 1, 4-butanediol as a reducing agent in transfer hydrogenation reactions
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1, 4-Butanediol is able to deliver two equivalents of H2 in hydrogen- transfer reactions to ketones, imines, and alkenes. Unlike simple alcohols, which establish equilibrium in the reduction of ketones, 1, 4-butanediol acts essentially irreversibly owing to the formation of butyrolactone, which acts as a thermodynamic sink. It is therefore not necessary to use 1, 4- butanediol in great excess in order to achieve reduction reactions. In addition, allylic alcohols are reduced to saturated alcohols through an isomerization/ reduction sequence using a ruthenium catalyst with 1, 4-butanediol as the reducing agent. Imines and alkenes are also reduced under similar conditions.
- Maytum, Hannah C.,Francos, Javier,Whatrup, David J.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 538 - 542
(2010/08/06)
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