- Elimination in sulfobetaine micelles: Effects of head group bulk
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Zwitterionic micelles of tetradecyldimethylammoniopropanesulfonate and tetradecyldibutylammoniopropanesulfonate, SB3-14 and SBBu3-14, respectively, accelerate the E2 reaction of OH- with 4-nitrophenethyl bromide (1b), but the reaction of phenet
- Brinchi, Lucia,Germani, Raimondo,Savelli, Gianfranco,Bunton, Clifford A.
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- Efficient Stille cross-coupling reaction catalyzed by the Pd(OAc) 2/Dabco catalytic system
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(Chemical Equation Presented) An efficient Pd(OAc)2/Dabco- catalyzed Stille cross-coupling reaction procedure has been developed. In the presence of Pd(OAc)2 and Dabco (triethylenediamine), various aryl halides including aryl iodides, aryl bromides, and activated aryl chlorides were coupled efficiently with organotin compounds to afford the corresponding biaryls, alkene, and alkynes in good to excellent yields. Furthermore, high TONs [turnover numbers, up to 980 000 TONs for the coupling reaction of 1-bromo-4-nitrobenzene and furan-2-yltributyltin] for the Stille cross-coupling reaction were observed.
- Li, Jin-Heng,Liang, Yun,Wang, De-Ping,Liu, Wen-Jie,Xie, Ye-Xiang,Yin, Du-Lin
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- EFFECT OF CYCLIC ACETAL-TYPE CATIONIC SURFACTANTS ON THE BASIC DEHYDROBROMINATION REACTION
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The reaction of 2-(p-nitrophenyl)ethyl bromide with hydroxide ion was studied at 50 and 25 deg C in the presence of cationic chemodegradable surfactants, i.e. trimethylammonium bromides Ia-c (alkyl: a = n-C9H19, b = n-C11H23, c = n-C13H27).The kinetic data were interpreted with the pseudo-phase ion-exchange (PIE) formalzm at both temperatures.The results indicate that the major source of rate enhancement is the increased reactant concentration in the small micellar reaction volume.The surfactant stability in micellar conditions was probed by means of a hydrolysis reaction of the surfactant 1,3-dioxolane ring.The kinetics of acid hydrolysis of Ia-c micelles, as a result of specific hydronium ion concentration, is one order of magnitude smaller than that of unaggregated systems.
- Wilk, Kazimiera A.,Bieniecki, Albert,Matuszewska, Barbara
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- P(CH3NCH2CH2)3N: A Nonionic Superbase for Efficient Dehydrohalogenation
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The commercially available nonionic Superbase P(CH3NH2CH2)3N (1) is far superior to DBU for the conversion of primary and secondary alkyl halides to alkenes. A reason for the efficacy of acetonitrile as a solvent for the halides requiring extended reaction times is presented.
- Arumugam, Subramaniam,Verkade, John G.
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- Low pressure vinylation of aryl and vinyl halides via Heck-Mizoroki reactions using ethylene
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Aryl bromides and iodides in the presence of catalytic amounts of a palladacycle derived from acetophenone oxime and 2 equiv of potassium acetate react with ethylene under ambient pressure (15-30 psi) to give the corresponding vinylarenes. The reactions work with both electron-deficient and electron-rich aryl compounds and tolerate wide variety of common functional groups. Vinyl bromides lead to 1,3-dienes in moderate yields.
- Smith, Craig R.,RajanBabu
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- Metal-free and base-free decarboxylation of substituted cinnamic acids in a deep eutectic solvent
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A metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene.
- Chen, Chen,Jian, Yuqing,Lei, Yuxin,Li, Bin,Peng, Caiyun,Sheng, Wen-Bing,Sumera, Yasmin,Wang, Wei,Zhang, Ming
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- Electrostatic Stabilization of the Transition State in Proton Transfer from Carbon
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The base-promoted reactions of 2-(p-nitrophenyl)ethyl chloride (1), 9-(chloromethyl)fluorene (2), 1-(2-chloro-2-propyl)indene (3), and 1-(2-acetoxy-2-propyl)indene (4) have been studied in 28 molpercent Me2SO4-H2O.They all exhibit rate-limiting proton transfer.Quinuclidine (Q) was found to be a more effective general base "catalyst" than hexafluoro-2-propanol anion (P-) in these reactions.Thus, after correction for the small difference in thermodinamic basicity, the following rate constant ratios kQ/kp- were obtained: 1.2, 4.4, 3.6, and 16, respectively.The small ratio for 1 indicates that partial desolvation of P- is responsible fo not more than a minor part of the rate differences between Q and P- in these reactions.It is concluded that the reactions of 2, 3, and 4 are accelerated by electrostatic interaction between the developing positive charge on the tertiary amine and the partial negative charge on the carbon atom in the transition state.This favorable electrostatic interaction seems to be considerably larger in methanol.
- Thibblin, Alf
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- Pd-grafted periodic mesoporous organosilica: An efficient heterogeneous catalyst for Hiyama and Sonogashira couplings, and cyanation reactions
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The high surface area of 2D-hexagonal periodic mesoporous organosilica (PMO) containing a phloroglucinol-diimine moiety inside the pore wall has been utilized for grafting Pd(ii) at the surface of the mesopores. This Pd-containing PMO material (Pd-LHMS-3) shows excellent catalytic activity in fluoride-free Hiyama cross-coupling reactions in water at alkaline pH conditions. Sonogashira cross-couplings between terminal alkynes and aryl halides take place in the presence of water and hexamine as base in the absence of any Cu co-catalyst. Cyanation of aryl halides is equally promoted with K4[Fe(CN) 6] as the cyanide source (in the absence of poisonous KCN, NaCN or Zn(CN)2) over Pd-LHMS-3. Excellent yield of the products, reusability and the facile work-up could make this Pd-grafted PMO material a unique catalyst for the synthesis of substituted benzonitriles, unsymmetrical biphenyls and di-substituted alkynes under environmentally benign reaction conditions. Further good yield of products and no evidence of leached Pd from the catalyst surface during the reaction and its smooth recovery confirm the true heterogeneity in these catalytic reactions.
- Modak, Arindam,Mondal, John,Bhaumik, Asim
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- Synthesis of Stilbene-Quinone Hybrids through Heck Reactions in PEG-400
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Styrenes were coupled with 3-iodolawsone in PEG-400 at 90 °C, leading stereoselectively to (E)-stilbene-quinone hybrids through Heck reactions. The best reaction conditions were found to be the use of NaOH (3 equiv) and 10 mol% of palladium acetate at 90 °C for 15 minutes. The chemical yields of the Heck reactions using styrenes with electron-withdrawing groups (65-98%) were greater than styrenes bearing electron-donating groups (7-32%) on the aromatic ring. In particular, the chemical yields of Heck reactions involving nitrostyrenes were the best ones observed.
- Demidoff, Felipe C.,De Souza, Fabrícia P.,Netto, Chaquip D.
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- Phosphane-free hiyama cross-coupling of aryl and heteroaryl halides catalyzed by palladium nanoparticles in ionic liquids
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Palladium nanoparticles (NPs) 2-5 nm in size and preformed by thermal reduction in nitrile-functionalized 3-(3-cyanopropyl)-1-methyl-1H-imidazol-3-ium hexafluorophosphate {[CN-bmim]PF6} act as an in situ catalyst for carbon-carbon bond-forming reactions of aromatic and heterocyclic halides with aryl- and vinyltrimethoxysilanes. A variety of biphenyl derivatives, substituted styrenes, and aromatic heterocycles were obtained in 76 to 98 % yield. We demonstrate for the first time the use of 1-butyl-3-methylimidazolium fluoride as an activator of the organosilanes with easy handling, storage, and workup in comparison to conventional fluorine sources such as tetrabutylammonium fluoride, which is indispensable for Hiyama coupling. Pd NPs immobilized in [CN-bmim]PF6 gave high yields of the cross-coupled products at a low catalyst loading of only 4 mol-%, and the catalyst could be reused and recycled up to four times with only a slight loss in catalytic activity. Phosphane-free Hiyama coupling of aryl- and vinyltrimethoxysilanes with aromatic and heterocyclic halides catalyzed by palladium nanoparticles in nitrile-functionalized ionic liquids to yield a range of biphenyl derivatives, substituted styrenes, and aromatic heterocycles is reported. The catalytic system can be recycled at least four times with only a slight loss in catalytic activity. Copyright
- Premi, Chanchal,Jain, Nidhi
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- Synthesis of Supported Planar Iron Oxide Nanoparticles and Their Chemo- and Stereoselectivity for Hydrogenation of Alkynes
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Nature uses enzymes to dissociate and transfer H2 by combining Fe2+ and H+ acceptor/donor catalytic active sites. Following a biomimetic approach, it is reported here that very small planar Fe2,3+ oxide nanoparticles (2.0 ± 0.5 nm) supported on slightly acidic inorganic oxides (nanocrystalline TiO2, ZrO2, ZnO) act as bifunctional catalysts to dissociate and transfer H2 to alkynes chemo- and stereoselectively. This catalyst is synthesized by oxidative dispersion of Fe0 nanoparticles at the isoelectronic point of the support. The resulting Fe2+,3+ solid catalyzes not only, in batch, the semihydrogenation of different alkynes with good yields but also the removal of acetylene from ethylene streams with >99.9% conversion and selectivity. These efficient and robust non-noble-metal catalysts, alternative to existing industrial technologies based on Pd, constitute a step forward toward the design of fully sustainable and nontoxic selective hydrogenation solid catalysts.
- Tejeda-Serrano, María,Cabrero-Antonino, Jose R.,Mainar-Ruiz, Virginia,López-Haro, Miguel,Hernández-Garrido, Juan C.,Calvino, José J.,Leyva-Pérez, Antonio,Corma, Avelino
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- Nano-NiFe2O4 as an efficient catalyst for regio- and chemoselective transfer hydrogenation of olefins/alkynes and dehydrogenation of alcohols under Pd-/Ru-free conditions
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Here, we have demonstrated the magnetic nano-NiFe2O4 catalyzed transfer hydrogenation of olefins/alkynes using isopropyl alcohol as a source of hydrogen under ligand/base/Pd-/Ru-metal-free conditions, and dehydrogenation of alcohols under oxidant-free conditions.
- Payra, Soumen,Saha, Arijit,Banerjee, Subhash
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- Salt Effects upon the Basic Dehydrobromination Reactions in Nonfunctional Micelles
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It was found that the effects of added univalent salts, NaX (X = Cl-, Br-, NO3-) upon the reaction of para-substituted 2-phenylethyl bromides with hydroxide ion in aqueous micellar solutions of hexadecyltrimethylammonium i
- Wilk, Kazimiera A.
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- Successive electron transfer reaction of the lithium salt of 5-methyl-5,10-dihydrophenazine anion with 4-nitrophenethyl bromide via 4-nitrostyrene
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The reaction of lithium salt of 5-methyl-5,10- dihydrophenazine anion with 4-nitrophenethyl bromide in 1,2- dimethoxyethane gave unexpected compounds, 1,2-bis[5-(10-methyl- 5,10-dihydrophenazinyl)]-1-(4-nitrophenyl)ethane and 1,4-bis(4- nitrophenyl)-1,4-b
- Sugimoto, Akira,Maruyama, Hideyuki,Takahashi, Wataru,Mizuno, Kazuhiko,Uehara, Kaku,Adachi, Tomohiro
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- Generation of the CF3 radical from trifluoromethylsulfonium triflate and its trifluoromethylation of styrenes
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The CF3 radical was generated from the reaction of S-(trifluoromethyl)diphenylsulfonium triflate with Na2S 2O4 or HOCH2SO2Na under suitable conditions without further reduction. Based on this, a method for the synthesis of α-trifluoromethylated ketones has been successfully developed.
- Zhang, Cheng-Pan,Wang, Zong-Ling,Chen, Qing-Yun,Zhang, Chun-Tao,Gu, Yu-Cheng,Xiao, Ji-Chang
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- Thermolysis of 3-Alkyl-4-phenyl-2-oxetanones and Related Compounds
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Thermolysis of cis- and trans-3-methyl-4-phenyl-2-oxetanones (1c and 1t), cis- and trans-3-isopropyl-4-phenyl-2-oxetanones (2c and 2t), and cis- and trans-3-tert-butyl-4-phenyl-2-oxetanones (3c and 3t) resulted in quantitative formation of the corresponding styrene which kept stereochemical uniformity.The strict stereospecificity suggests the concerted nature of the fragmentation.The rates of reaction of these 2-oxetanones and related compounds, including 3,3-dimethyl-4-phenyl-2-oxetanone (4), 3,3-dimethyl-4,4-diphenyl-2-oxetanone (5), 4,4-dimethyl-3-phenyl-2-oxetanone (6), and cis- and trans-3,4-diphenyl-2-oxetanones (7c and 7t), in decane and/or dodecane were studied.The reactivity of 4-phenyl-2-oxetanone (8) was estimated from that of p-nitro derivative 9.The relative rates at 150 deg C were 1c/2c/3c/1t/2t/3t/4/5/6/7c/7t/8, 1.0:0.31:0.028:11:4.3:2.1:0.29:6.9:3.8:(1.7):(13):(17).The least substituted 8 exhibited the highest reactivity.In 3,4-disubstituted derivatives, the trans isomer reacted more rapidly than the corresponding cis isomer without exception.For 1-3, it is shown that the bulkier the alkyl group, the slower the fragmentation.Since significant positive charge development has been previously shown to occur only at C-4, but not at C-3, the reactivity sequence cannot be attributed to the electronic effect of the alkyl group.On the other hand, if an assumption that the important factor is the increased steric strain at the concerted 2s + 2a transition state is accepted, the results can be explained reasonably.Indeed, log k1 values of 1c, 2c, 3c, and 8 correlated quite linearly with the steric parameter Es or ν.The relative reactivities of 4-7 are also discussed.
- Imai, Toshiro,Nishida, Shinya
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- A Change in the Rate-Determining Step in the E1cB Reactions of N-(2-(4-Nitrophenyl)ethyl)pyridinium Cations
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Second-order rate constants have been measured (aqueous solution, I = 1.0, 25 deg C) for the hydroxide ion catalyzed elimination reactions of 12 N-(2-(4-nitrophenyl)ethyl)pyridinium cations (3) bearing a variety of substituents in the pyridine ring.Broensted plots as a function of the basicity of the pyridine leaving group are concave-down, which is consistent with a change in rate-determining step within an E1cB mechanism.These plots are characterized by βlg = -0.17 for the rate-determining deprotonation for pKBH lg = -0.39 for the rate-determining expulsion of the pyridine nucleofuge from the carbanionic intermediate for pKBH > 6.5.Elimination reactions in basic D2O occur without any significant incorporation of deuterium into the 4-nitrostyrene product, and require the presence of a hydrogen-bonded carbanionic intermediate in which nucleofuge expulsion occurs faster than exchange of hydrogen-bonding water molecules.Rate-determining deprotonation in these elimination reactions occurs 50-fold more slowly than for the corresponding reactions of the N-quinuclidinium cations that have also been reported to have βlg = -0.17, but which do not show an analogous change in the rate-determining step upon variation of the nucleofuge basicity.The analogous elimination of the 1-methyl-3-imidazolium cation occurs a further 30-fold more slowly than that predicted for 3 having a pyridine leaving group of the same basicity as 1-methylimidazole.The E1cB reactions of 3 are similar to the analogous reactions of N-(2-cyanoethyl)pyridinium cations (1) in displaying a change in the rate-determining step with nucleofuge basicity; however, theβlg values for 1 and 3 are quite different for both k1 and k2/k-1.
- Bunting, John W.,Kanter, James P.
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- Wittig reaction by using DBU as a base
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The reaction of methyltriphenylphosphonium bromide with DBU in refluxing dichloromethane or toluene afforded methylenetriphenylphosphorane, which further reacted with benzaldehydes to give styrenes in good yields. Semistabilized ylide, benzylidenetriphenylphosphorane was also synthesized by using DBU, which reacted with aldehydes to afford olefins in nearly quantitative yields.
- Okuma, Kentaro,Sakai, Osami,Shioji, Kosei
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- Resolution of the non-steady-state kinetics of the elimination of HBr from 2-(p-nitrophenyl)ethyl bromide in alcohol/alkoxide media
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Non-steady-state kinetic studies reveal that the elimination of HBr from 2-(p-nitrophenyl)ethyl bromide in alcohol/alkoxide media, the classical concerted E2 reaction, actually takes place by a two-step mechanism involving the intermediate formation of th
- Handoo, Kishan L.,Lu, Yun,Zhao, Yixing,Parker, Vernon D.
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- Cocatalysis by tetravalent tin compounds in phase-transfer catalyzed fluorination of alkyl halides and sulfonates
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Phase-transfer catalyzed fluorination of alkyl halides or sulfonates is co-catalyzed efficiently by triorganotin halides. The cocatalytic action is due to continuous formation of lipophilic hypervalent triorganodifluorostannate anions, which act as fluori
- Ma?kosza, Mieczys?aw,Bujok, Robert
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- Rapid Access to Ortho-Alkylated Vinylarenes from Aromatic Acids by Dearomatization and Tandem Decarboxylative C-H Olefination/Rearomatization
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A two-step straightforward method for the preparation of ortho-alkylated vinylarenes from readily available benzoic acids is described. The synthetic route involves the dearomatization of benzoic acids by Birch reduction providing alkylated cyclohexa-2,5-dienyl-1-carboxylic acids. The diene subsequently undergoes a decarboxylative C-H olefination followed by rearomatization to deliver ortho-alkylated vinylarene. Mechanistic studies suggest that a Pd/Ag bimetallic catalytic system is important in the tandem decarboxylative C-H olefination/rearomatization step.
- Tsai, Hung-Chang,Huang, Yen-Hsiang,Chou, Chih-Ming
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- In Situ Generation of Formaldehyde and Triphenylphosphine from (Hydroxymethyl)triphenylphosphonium and Its Application in Wittig Olefination
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The reaction of (hydroxymethyl)triphenylphosphonium with benzylic or allylic halide under basic conditions at room temperature affords terminal alkenes in 61-89% yields. In this reaction, both formaldehyde and triphenylphosphine are in situ generated from (hydroxymethyl)triphenylphosphonium and further undergo Wittig olefination with benzylic or allylic halide.
- Huang, Wenhua,Xu, Jie
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- Methyltriphenylphosphonium Methylcarbonate, an All-In-One Wittig Vinylation Reagent
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The methyltriphenylphosphonium methylcarbonate salt [Ph3PCH3][CH3OCO2], obtained directly by quaternarization of triphenylphosphine with dimethylcarbonate, is a latent ylide that promotes Wittig vinylation of aldehydes and ketones. Alkenes are obtained simply by mixing [Ph3PCH3][CH3OCO2] and the carbonyl and heating in a solvent (no base, no halides, and no inorganic byproducts). Deuterium exchange experiments and the particularly short anion-cation distance measured by XRD in [Ph3PCH3][CH3OCO2] allowed to explain the nature and reactivity of this species. Green chemistry metrics (atom economy, mass index, environmental factor) indicate that this vinylation procedure is more efficient than comparable ones. Deuterated [Ph3PCD3][CH3OCO2] promoted the synthesis of deuterated olefins. Add carbonyl and go! The Wittig reaction is widely applied, despite having shortcomings such as low atom economy (AE), the necessity to use solvents, and stoichiometric amounts of waste from generating the ylide. [Ph3PCH3][CH3OCO2] is a latent phosphorous ylide that promotes Wittig vinylation of aldehydes and ketones by simply heating with the carbonyl. No external base and no halides involved, and the protocol offers good AE, environmental factor, and mass index.
- Cattelan, Lisa,Noè, Marco,Selva, Maurizio,Demitri, Nicola,Perosa, Alvise
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- Palladium Cross-Coupling Reactions of Aryl Fluorosulfonates: An Alternative to Triflate Chemistry
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A new and efficient electrophilic partner for palladium(0)-catalyzed cross coupling is reported.Aryl fluorosulfonates are readily prepared in high yield by treatment of the appropriate phenol with fluorosulfonate anhydride.The palladium-catalyzed coupling reactions of these fluorosulfonates with vinyl- and aryltin reagents, as well as organozinc chlorides, takes place under mild conditions in a regio- and stereoselective manner.
- Roth, Gregory P.,Fuller, Carl E.
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- Heterogeneous One-Pot Carbonylation and Mizoroki–Heck Reaction in a Parallel Manner Following the Cleavage of Cinnamaldehyde Derivatives
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Carbon monoxide (CO) and styrene derivatives that can be both generated by a palladium on carbon (Pd/C)-catalyzed carbon–carbon (C?C) bond cleavage reaction of cinnamaldehyde derivatives were effectively utilized in further palladium-catalyzed C?C bond forming reactions in a direct and practical way. CO derived from simple and affordable CO carriers such as cinnamaldehyde or terephthalaldehyde was efficiently employed in the in situ CO fixation with various aromatic iodides through a palladium-catalyzed carbonylation followed by an inter- or intramolecular coupling reaction with alcohols to afford the corresponding esters or lactones, respectively. Styrene derivatives were also efficient substrates in an in situ Mizoroki–Heck-type cross-coupling reaction with aryl iodides, leading to the effective formation of asymmetric stilbenes. The decarbonylation of cinnamaldehyde derivatives and the subsequent independent syntheses of both esters/lactones and 1,2-diarylethenes could be achieved in a virtual one-pot and in situ reaction using a H-shaped pressure-tight glass-sealed tube consisting of two independent but laterally connected reaction tubes in the gas space.
- Hattori, Tomohiro,Ueda, Shun,Takakura, Ryoya,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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- Efficient heterogeneous vinylation of aryl halides using potassium vinyltrifluoroborate
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An efficient heterogeneously palladium catalysed procedure for the vinylation of aryl iodides and bromides is reported. Using common reaction conditions (Pd/C 2 mol %, AcONa·3H2O, NMP or NMP/H2O), good to complete conversions (40-100%) with high selectivities (79-100%) towards the expected vinylaromatic were achieved.
- Joucla, Lionel,Cusati, Giuseppe,Pinel, Catherine,Djakovitch, Laurent
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- OIL-IN-WATER MICROEMULSIONS BASED ON CHEMODEGRADABLE SURFACTANTS AS REACTION MEDIA
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The reaction of 2-(p-nitrophenyl)ethyl bromide with hydroxide ion was studied in oil-in-water (o/w) microemulsions at 50 deg C.The octane-in-water microemulsion systems were stabilized by chemodegradable cyclic acetal-type cationic surfactants as (2-alky
- Bieniecki, Albert,Wilk, Kazimiera A.
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- Preparation of 4-nitrostyrene
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The interaction of D,L-1-(4-nitrophenyl)ethanol with SOCl2 and P4O10 has been studied. In the reaction of D,L-1-(4-nitrophenyl)ethanol with SOCl2 a mixture of 1-(4-nitrophenyl)-1-chloroethane, 1,1′-bis-(4-nitrop
- Shultsev
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- Design and synthesis of water-soluble chelating polymeric materials for heavy metal ion sequestration from aqueous waste
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Sequestration and removal of dissolved heavy metal ions from aqueous waste streams is a challenging task. Ethylenediaminetetraacetic acid (EDTA) is a hexadentate chelating ligand capable of forming 1:1 complex with various heavy metal ions while iminodiacetic acid (IDA) is analogous to half a unit of EDTA. A new styrene based monomer M1 bearing dimethyl iminodiacetate group was designed and synthesized in good yield to meet this objective. Free radical polymerization of M1 generated the homopolymer, which upon base hydrolysis generated the water-soluble chelating homopolymer P10, bearing sodium salt of IDA as the chelating group. The overall yield of P10 was 76.80% and the solubility was 5 mg/mL at room temperature. The water soluble polymer P10 was investigated for its ability to bind various heavy metal ions by UV–vis spectroscopy and was found to efficiently sequester Cu2+, Cd2+, Zn2+, Pb2+, Ni2+, Co2+, Cr3+, Fe2+ and Fe3+. The effect of pH on Cu2+ binding with P10 showed that every two IDA bearing monomeric repeat units binds with one Cu2+ ion at pH 7 suggesting that it forms complexes analogous to EDTA. Thermogravimetric analysis showed that the synthesized polymer possesses high thermal stability up to 400 °C. The potential for recovery and reuse of the polymer has been demonstrated with Cu2+ ion. The reported results suggest that this water-soluble chelating homopolymer is an excellent material with very high potential for application in wastewater treatment.
- Jacob, Josemon,Tyagi, Reshu
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- Layered double hydroxide-supported nanoplatinum: An efficient and reusable ligand-free catalyst for heck and stille coupling of iodoarenes
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A layered double hydroxide-supported nanoplatinum catalyst is employed in the Heck and Stille cross-coupling of a wide range of iodoarenes to give the corresponding cross-coupled products in good to excellent yields. The catalyst is recovered by centrifugation and reused over a number of cycles with consistent activity. Georg Thieme Verlag Stuttgart.
- Kantam, M. Lakshmi,Roy, Moumita,Roy, Sarabindu,Subhas,Sreedhar, Bojja,Choudary
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- Intramolecular Dehydration of β-Hydroxyalkylphosphonic Acid Monoesters. A Novel Type of Olefin Formation
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The title reaction using dicyclohexylcarbodiimide (DCC) gave stereospecifically the corresponding olefins in good yields via tetracoordinate 1,2-oxaphosphetanes.Use of more than one equivalent of DCC afforded better yields of the olefin.
- Kawashima, Takayuki,Nakamura, Mio,Nakajo, Akira,Inamoto, Naoki
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- 4,4,6-Trimethyl-2-vinyl-1,3,2-dioxaborinane: A superior 2-carbon building block for vinylboronate Heck couplings
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4,4,6-Trimethyl-2-vinyl-1,3,2-dioxaborinane is a superior reagent in terms of stability and reactivity in comparison to the vinylboronate pinacol ester, giving improved selectivity for Heck versus Suzuki coupling with both aryl iodides and bromides, and being easier to prepare and store.
- Lightfoot, Andrew P.,Maw, Graham,Thirsk, Carl,Twiddle, Steven J. R.,Whiting, Andrew
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- STYRENE DERIVATIVES VIA PALLADIUM-CATALYZED VINYLATION OF ARYL IODIDES
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A new and efficient method for the preparation of styrene derivatives via Pd-catalyzed vinylation of aromatic systems, using vinyltrimethylsilane as an ethylene equivalent, is described.
- Hallberg, Anders,Westerlund, Christer
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- Efficient and selective Stille cross-coupling of benzylic and allylic bromides using bromobis(triphenylphosphine)(N-succinimide)palladium(II)
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Allylic and benzylic bromides are cross-coupled with organostannanes efficiently using the precatalyst [Pd(NCOC2H4CO)(PPh 3)2Br] 1. Significantly, these reactions do not require the use of hexamethylphosphoramide (HMPA) as the solvent, or additional ligands, such as trifurylphosphine or triphenylarsine. Selectivity for benzyl bromide over bromobenzene is observed for precatalyst 1, against the precatalysts, bromobis(triphenylphosphine)(benzyl)palladium(II) and bis(triphenylphosphine) palladium(II) bromide.
- Crawforth, Catherine M.,Fairlamb, Ian J. S.,Taylor, Richard J. K.
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- Hydroxyl Assisted Rhodium Catalyst Supported on Goethite Nanoflower for Chemoselective Catalytic Transfer Hydrogenation of Fully Converted Nitrostyrenes
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Control of chemoselectivity is a special challenge for the reduction of nitroarenes bearing one or more unsaturated groups. Here, we report a flower-like Rh/α-FeOOH catalyst for the chemoselective hydrogenation of nitrostyrene to vinylaniline over full conversion, which benefits the new functionalized aminostyrene because the multisubstituted aminostyrenes are usually commercially unavailable. This catalyst does not only show desirable selectivity for the vinylanilines, but also exhibits the inertness to various other reducible groups over wide reaction duration. The catalytic selectivity for the reduction of the nitro group towards vinyl group was investigated by the control experiments and FT-IR analysis. We have found that the abundant hydroxyl groups in the α-FeOOH may contribute to the improvement of catalytic activity and selectivity. Furthermore, the catalyst exhibits excellent stability and keeps its catalytic performance even after 6 cycles. (Figure presented.).
- Hu, Zenan,Ai, Yongjian,Liu, Lei,Zhou, Junjie,Zhang, Gang,Liu, Hongqi,Liu, Xiangyu,Liu, Zhibo,Hu, Jianshe,Sun, Hong-bin,Liang, Qionglin
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- Synthesis and electronic effect of the substituents on anionic ring- opening polymerization of para-substituted phenyl cyclopropanes
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As an extension of studies in the anionic polymerization of activated cyclopropanes with electronically push-pull substituents, p-substituted phenylcyclopropane-1,1-dicarbonitriles having Me0, Me, H, Cl, and NO2 as substituents were prepared. The electronic effects of substituents upon the ring-opening reaction during anionic polymerizations were examined by determining the rate constants of polymerizations, conversions and molecular weights of the resulting polymers. The rate constants of polymerization(k(p)) in DMSO by 2 mole% cyanide ion at 35 °C were p-Me0=0.45, p-Me=0.14, p- H=0.07, p-Cl=0.06 and p-NO2=0.01 litter/mole.sec, and the rate constants of polymerization in DMSO by 5 mole% pyridine at 35 °C were p-Me0=048, p- Cl=7.6 x 10-3 and p-NO2=1.64 x 10-3 liter/mole.sec., respectively. The electronic effect exerted by substituents were well consistent with the Hammett relationship(log k/k(o)=σ ρ) when Brown's σ+ constants were used. The reaction sensitivity constants(ρ) obtained from cyanide ion initiator were -1.0 and -0.94 for pyridine initiation. These results indicate that the anionic ring-opening polymerization of p-substituted phenylcyclopropanes is carried out via highly conjugated zwitterionic transition state in the ring opening reaction. Furthermore, in the case of the polymerization initiated by pyridine or triethylamine, the formation of macrozwitterion during polymerization is a feasible mechanism.
- Kim, Jin-Bong,Cho, Iwhan
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- Wittig like methylenation of aldehydes in a microflow system: Selective methylenation by differential of plural reactions
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Methylenation of aldehydes with bis(iodozincio)methane was performed using a microflow system. Treatment of a dialdehyde with bis(iodozincio)methane in the system can divide two methylenation reactions and realize selective transformation.
- Takada, Yoshiaki,Matsubara, Seijiro
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- Recoverable palladium-catalyzed carbon-carbon bond forming reactions under thermomorphic mode: Stille and suzuki-miyaura reactions
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The reaction of [PdCl2(CH3CN)2] and bis-4,40-(RfCH2OCH2)-2,2'-bpy (1a-d), where Rf = n- C11F23 (a), n-C10F21 (b), n-C9F19 (c) and n-C8F17 (d), respectively, in the presence of dichloromethane (CH2Cl2) resulted in the synthesis of Pd complex, [PdCl2[4,4'-bis-(RfCH2OCH2)-2,2'-bpy] (2a-d). The Pd-catalyzed Stille arylations of vinyl tributyltin with aryl halides were selected to demonstrate the feasibility of recycling usage with 2a as the catalyst using NMP (N-methyl-2-pyrrolidone) as the solvent at 120-150 °C. Additionally, recycling and electronic effect studies of 2a-c were also carried out for Suzuki-Miyaura reaction of phenylboronic acid derivatives, 4-X-C6H4-B(OH)2, (X = H or Ph) with aryl halide, 4-Y-C6H4-Z, (Y = CN, H or OCH3; Z = I or Br) in dimethylformamide (DMF) at 135-150 °C. At the end of each cycle, the product mixtures were cooled to lower temperature (e.g., -10 °C), and then catalysts were recovered by decantation with Pd leaching less than 1%. The products were quantified by gas chromatography/mass spectrometry (GC/MS) analysis or by the isolated yield. The complex 2a-catalyzed Stille reaction of aryl iodides with vinyl tributyltin have good recycling results for a total of 8 times, with a high yield within short period of time (1-3 h). Similarly, 2a-c-catalyzed Suzuki-Miyaura reactions also have good recycling results. The electronic effect studies from substituents in both Stille and Suzuki-Miyaura coupling reactions showed that electron withdrawing groups speed up the reaction rate. To our knowledge, this is the first example of recoverable fluorous long-chained Pd-catalyzed Stille reactions under the thermomorphic mode.
- Chan, Ka Long,Chiu, Chiao-Fan,Elakkat, Vijayanath,Lu, Norman,Shen, Chia-Rui,Su, Han-Chang,Tessema, Eskedar,Tsai, Zong-Lin
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- Recoverable homogeneous palladium(0) catalyst for cross-coupling reactions of arenediazonium salts with potassium organotrifluoroborates: Detection of catalytic intermediates by electrospray ionization mass spectrometry
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Fifteen-membered triolefinic macrocyclic palladium(0) complex 1, (E,E,E)-1-ferrocenylsulfonyl-6,11-bis[(4-methylphenyl)sulfonyl]-1,6, 11-triazacyclopentadeca-3,8,13-trienepalladium(0), is an active and recoverable catalyst for Suzuki-Miyaura cross-couplings between arenediazonium salts and potassium organotrifluoroborates. The reactions were performed under aerobic conditions at room temperature and without added base. Use of electrospray ionization mass spectrometry (ESI-MS) allowed the direct detection and identification of several intermediates, which furthers the study of the mechanistic aspects of the Suzuki-Miyaura reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Masllorens, Judit,Gonzalez, Ivan,Roglans, Anna
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- Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes
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(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
- Lebel, Helene,Davi, Michael,Diez-Gonzalez, Silvia,Nolan, Steven P.
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- Nitrile-functionalized pyrrolidinium ionic liquids as solvents for cross-coupling reactions involving in situ generated nanoparticle catalyst reservoirs
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A series of nitrile-functionalized pyrrolidinium-based ionic liquids have been prepared and characterized by spectroscopic methods and X-ray crystallography. The application of these new ionic liquids as reaction media for Suzuki and Stille C-C cross-coupling reactions has been investigated and compared with related imidazolium and pyridinium systems (including those with and without nitrile functionalities). The nature of the ionic liquid strongly influences the catalyzed reaction and it would appear that, in addition to the nitrile group, the strength of anion-cation pairing in the ionic liquid and the viscosity of the ionic liquid play critical roles. Nanoparticles are also detected following catalysis and their role, and the influence of the ionic liquid on them, is assessed. The ability to use the nitrile-functionalized pyrrolidinium-based ionic liquids diluted in other (non-functionalized) ionic liquids is also described.
- Cui, Yugang,Biondi, Ilaria,Chaubey, Manish,Yang, Xue,Fei, Zhaofu,Scopelliti, Rosario,Hartinger, Christian G.,Li, Yongdan,Chiappe, Cinzia,Dyson, Paul J.
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- Hetero-Diels-Alder cycloadditions of α,β-unsaturated acyl cyanides. Part 4. Substituent effects in reactions with p-substituted styrenes
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Cycloadditions of α,β-unsaturated acyl cyanides (=2-oxonitriles) 1-6 to styrene and its p-substituted derivatives 7a-f,h are of inverse electron demand and provide, under mild conditions, regio- and stereo-selectively 2- aryl-3,4-dihydro-2H-pyran-6-carbonitriles 8-13, generally in good yield. Rates for the cycloaddition of acryloyl cyanide 1 to p-substituted styrenes, determined in competition reactions of substrate pairs relative to that of styrene, increase in the order of electron-donating ability NO2 + substituent constants (a Hammett-type plot), gives a reaction constant ρ(p)+ of -1.47 ± 0.17, supporting a concerted mechanism.
- Zhuo, Jin-Cong,Wyler, Hugo
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- Suzuki cross-coupling reactions of potassium alkenyltrifluoroborates
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(formula presented) The palladium-catalyzed coupling reaction of potassium alkenyltrifluoroborates with aryl or alkenyl halides or triflates proceeds readily with good yields. The trifluoroborates are air-and moisture-stable solids that can be stored indefinitely. The cross-coupling can be effected using PdCl2(dppf)-CH2Cl2 as the catalyst in n-PrOH in the presence of Et3N. A variety of functional groups are tolerated. ? Dedicated to Professor Herbert C. Brown on the occasion of his 90th birthday.
- Molander, Gary A.,Rivero, Marta Rodriguez
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- Pd?Zn Alloy Nanoparticles Encapsulated into Mesoporous Silica with Confinement Effect for Highly Selective Semi-Hydrogenation of Phenylacetylene
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In the process of hydrogenation of phenylacetylene to styrene, it is a crucial step to improve the reaction selectivity of the target product styrene. Herein, we have designed the Pd?Zn alloy nanoparticles encapsulated into mesoporous silica with confinement effect (Pd?Zn@MS) for highly selective semi-hydrogenation of phenylacetylene via annealing the Pd NPs@ZIF-8 in reducing atmosphere. The as-obtained Pd?Zn@MS achieved up to the 95 % of conversion rate and 92 % of selectivity, because the mesoporous silica exhibits a steric hindrance effect for the reactant molecular size, and the Pd?Zn alloy nanoparticles shows the high selectivity for the target product styrene. DFT calculations demonstrates that the PdZn alloy nanoparticles can reduce significantly the desorption energy barrier of styrene from 1.72 eV to 0.95 eV, compared with the Pd nanoparticles. Meanwhile the mesoporous silica in the outer layer greatly guarantees the stability of the catalytic performance of the catalyst, and the catalytic performance did not drop after the five-cycle test. This work provides a new idea for the selective hydrogenation of phenylacetylene and the process of limited-area catalysis.
- Li, Zhenxing,Hu, Mingliang,Liu, Bowen,Liu, Jiahao,Wang, Ping,Yao, Jiasai,Zhang, Xin,He, Miao,Song, Weiyu
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- Reusable copper-catalyzed cross-coupling reactions of aryl halides with organotins in inexpensive ionic liquids
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A combination of Cu2O nanoparticles with P(o-tol)3 shows highly catalytic activity for the Stille cross-coupling reaction. A series of copper catalysts and ligands were evaluated, and Cu2O nanoparticles combined with P(o-tol)3 provided the best results. In the presence of Cu2O nanoparticles and P(o-tol)3, a variety of aryl halides including aryl chlorides underwent the Stille reaction with organotins smoothly in moderate to excellent yields using inexpensive TBAB (n-Bu4NBr) as the medium. It is noteworthy that the Cu 2O/P(o-tol)3/TBAB system can be recovered and reused at least three times without any loss of catalytic activity among the reactions of aryl iodides and activated aryl bromides.
- Li, Jin-Heng,Tang, Bo-Xiao,Tao, Li-Ming,Xie, Ye-Xiang,Liang, Yun,Zhang, Man-Bo
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- Tertiary arsine ligands for the Stille coupling reaction
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The Stille coupling reaction is one of the most important coupling reactions. It is well known that the triphenylarsine ligand can accelerate the reaction rate of Stille coupling. However, other arsine ligands have never been investigated for the Stille c
- Chishiro, Akane,Imoto, Hiroaki,Inaba, Ryoto,Konishi, Masafumi,Naka, Kensuke,Yumura, Takashi
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- Valorisation of urban waste to access low-cost heterogeneous palladium catalysts for cross-coupling reactions in biomass-derived γ-valerolactone
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Herein we report a simple protocol for the valorisation of a common urban biowaste. The lignocellulosic biomass obtained after the pre-treatment of pine needle urban waste is efficiently transformed into a low-cost support (PiNe) for the immobilization of Pd nanoparticles. The final Pd/PiNe heterogeneous catalyst features a small particle size (4.5 nm) and a metal loading (9.9 wt%) comparable with most commercially available and generally used counterparts. In this contribution, we tested the catalytic efficiency of the Pd/PiNe system in two representative cross-couplings, Heck and Hiyama reactions, and compared the results obtained with commercial Pd/C catalyst. The good reactivity in the biomass-derived solvent (GVL) confirms that the Pd/PiNe heterogeneous catalyst is a valid system that can be integrated into a waste valorization chain within a circular economy approach. In addition, the efficiency of the catalyst has also been extended to perform the challenging consecutive Hiyama-Heck reaction to afford differently substituted (E)-1,2-diarylethenes.
- Valentini, Federica,Ferlin, Francesco,Lilli, Simone,Marrocchi, Assunta,Ping, Liu,Gu, Yanlong,Vaccaro, Luigi
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supporting information
p. 5887 - 5895
(2021/08/23)
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- The Stereoselective Oxidation of para-Substituted Benzenes by a Cytochrome P450 Biocatalyst
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The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol-CYP)?1.min?1) and with total turnover numbers of up to 20,000. Ethyl α-hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S-oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4-methoxybenzoic acid-bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme.
- Chao, Rebecca R.,Lau, Ian C.-K.,Coleman, Tom,Churchman, Luke R.,Child, Stella A.,Lee, Joel H. Z.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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supporting information
p. 14765 - 14777
(2021/09/14)
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- In-situ facile synthesis novel N-doped thin graphene layer encapsulated Pd@N/C catalyst for semi-hydrogenation of alkynes
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Transition metal-catalyzed semi-hydrogenation of alkynes has become one of the most popular methods for alkene synthesis. Specifically, the noble metal Pd, Rh, and Ru-based heterogeneous catalysts have been widely studied and utilized in both academia and industry. But the supported noble metal catalysts are generally suffering from leaching or aggregation during harsh reaction conditions, which resulting low catalytic reactivity and stability. Herein, we reported the facile synthesis of nitrogen doped graphene encapsulated Pd catalyst and its application in the chemo-selective semi-hydrogenation of alkynes. The graphene layer served as “bulletproof” over the active Pd Nano metal species, which was confirmed by X-ray and TEM analysis, enhanced the catalytic stability during the reaction conditions. The optimized prepared Pd@N/C catalyst showed excellent efficiency in semi-hydrogenation of phenylacetylene and other types of alkynes with un-functionalized or functionalized substituents, including the hydrogenation sensitive functional groups (NO2, ester, and halogen).
- Lin, Shanshan,Liu, Jianguo,Ma, Longlong,Sun, Jiangming
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- Vinyl-Fluorene Molecular Wires for Voltage Imaging with Enhanced Sensitivity and Reduced Phototoxicity
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Fluorescent voltage indicators are an attractive alternative for studying the electrical activity of excitable cells; however, the development of indicators that are both highly sensitive and low in toxicity over long-term experiments remains a challenge.
- Boggess, Steven C.,Gandhi, Shivaani S.,Benlian, Brittany R.,Miller, Evan W.
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supporting information
p. 11903 - 11907
(2021/08/20)
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- Cross-Coupling Reactions with 2-Amino-/Acetylamino-Substituted 3-Iodo-1,4-naphthoquinones: Convenient Synthesis of Novel Alkenyl- And Alkynylnaphthoquinones and Derivatives
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Functionalized 1,4-naphthoquinones have been employed as versatile synthons in organic synthesis, in addition to presenting a large array of biological activities. Herein, the applications of 2-amino-/ acetylamino-substituted 3-iodo-1,4-naphthoquinones in cross-coupling reactions are described to successfully afford sixteen novel 3-styryl-1,4-naphthoquinones (amino-stilbene-quinone hybrids) and four 3-alkynyl-1,4-naphthoquinone in overall good yields. Interestingly, the alkynylated derivatives could be obtained from ligand- and Pd-free Cu I -mediated cross-coupling reactions, after extensive investigations to exclude Pd as a co-catalyst. Lastly, the desilanized terminal alkyne was subjected to click chemistry reactions to give two novel triazole-1,4-naphthoquinone hybrids.
- Demidoff, Felipe C.,Rodrigues Filho, Eduardo José P.,De Souza, Andréa Luzia F.,Netto, Chaquip D.,De Carvalho, Leandro L.
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supporting information
p. 4097 - 4109
(2021/08/31)
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- Thiourea-Mediated Halogenation of Alcohols
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The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
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supporting information
p. 12901 - 12911
(2020/11/26)
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- Creation of Redox-Active PdSx Nanoparticles Inside the Defect Pores of MOF UiO-66 with Unique Semihydrogenation Catalytic Properties
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Semihydrogenation of alkynes to produce alkenes is very important in the industry; however, over-hydrogenation heavily complicates the postprocesses, which are highly energy consuming and not environmentally friendly. One of the most efficient pathways to solve this challenging issue is to develop highly selective catalysts that could only hydrogenate alkynes and are inactive in hydrogenation of alkenes. This work presents herein an efficient catalyst, consisting of in situ created PdS0.53 nanoparticles as the redox-active sites inside the defect pores of metal–organic framework UiO-66, which demonstrates very high alkene selectivity (up to 99.5%) in semihydrogenation of easily over-hydrogenated terminal alkynes. In contrast to the traditional catalysts, strict control over the reaction time becomes the nonessential condition because the catalyst system is almost inactive in hydrogenation of alkenes. Therefore, this paradigm work provides a practically applicable pathway for the development of efficient catalysts with unique catalytic properties for selective semihydrogenation reactions.
- Dong, Ming-Jie,Wang, Xuan,Wu, Chuan-De
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- On-Demand, Ultraselective Hydrogenation System Enabled by Precisely Modulated Pd-Cd Nanocubes
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The pursuit of efficient hydrogenation nanocatalysts with a desirable selectivity toward intricate substrates is state-of-the-art research but remains a formidable challenge. Herein, we report a series of novel PdCdx nanocubes (NCs) for ultraselective hydrogenation reactions with flexible tuning features. Obtaining a desirable conversion level of the substrates (e.g., 4-nitrophenylacetylene (NPA), 4-nitrobenzaldehyde (NBAD), and 4-nitrostyrene (NS)) and competitive selectivity for all potential hydrogenation products have been achieved one by one under optimized hydrogenation conditions. The performance of these PdCdx NCs displays an evident dependence on both the composition and the use of Cd and a need for a distinct hydrogen source (H2 or HCOONH4). Additionally, for the selectivity of hydrogen to be suitably high, the morphology of the NCs has a very well-defined effect. Density functional theory calculations confirmed the variation of adsorption energy for the substrate and hydrogenation products by carefully controlled introduction of Cd, leading to a desirable level of selectivity for all potential hydrogenation products. The PdCdx NCs also exhibit excellent reusability with negligible activity/selectivity decay and structural/composition changes after consecutive reactions. The present study provides an advanced strategy for the rational design of superior hydrogenation nanocatalysts to achieve a practical application for desirable and selective hydrogenation reaction efficiency.
- Feng, Yonggang,Xu, Weiwei,Huang, Bolong,Shao, Qi,Xu, Lai,Yang, Shize,Huang, Xiaoqing
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supporting information
p. 962 - 972
(2020/02/20)
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- Pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex dye sensitizer as well as preparation method and application thereof
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The invention relates to a D(-A-pi-A) type pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex dye sensitizer (BDTT-im-Cd) as shown in a formula 1, and a preparation method and application thereof. The dye sensitizer is a D(-A-pi-A) complex synthesized by reacting a pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex containing functional groups such as anauxiliary electron acceptor (A), a pi bridge, a main electron acceptor (A), an anchoring group and the like with an electron donor (D), namely, benzodithiophene bithiophene (BDTT) through a Heck coupling reaction. Experiments show that a dye-sensitized solar cell with the BDTT-im-Cd as the dye sensitizer shows good effects in photovoltaic performance tests, wherein photoelectric conversion efficiency (PCE) reaches 9.13%, the thermal decomposition temperature of a dye reaches 300 DEG C or above, thermal stability is high, the requirements of photovoltaic materials can be met, and the dye sensitizer has a certain prospect in the development and application of the dye-sensitized solar cell. The formula 1 shows the structure of the complex BDTT-im-Cd.
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- Exploring the nitro group reduction in low-solubility oligo-phenylenevinylene systems: Rapid synthesis of amino derivatives
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A small series of amino oligo-phenylenevinylenes (OPVs) were successfully synthesized from their nitro-analogs in a rapid, simple, and highly efficient fashion employing a sodium sulfide/pyridine system as a reducing agent. In this research, classic and sustainable reduction methodologies including NH4HCO2/Zn and a choline chloride/tin (II) chloride deep eutectic solvent (DES) were also evaluated, showing degradation products, incomplete reactivity, and product isolation difficulties in all cases. The straightforward Na2S/pyridine synthetic protocol proved to maintain the E-E stereochemistry of the OPV backbone that has been previously assembled by the Mizoroki–Heck cross-coupling reaction. Also, the optoelectronic properties were determined and discussed, considering the amino group insertion in these conjugated systems as a contribution for future construction of novel materials with applications in supramolecular electronics, light harvesting, and photocatalysis.
- Acelas, Mauricio,Sierra, Andrés Felipe,Sierra, César A.
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supporting information
p. 1335 - 1352
(2020/03/04)
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- Method for preparing styrene derivative from ionic liquid
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The invention belongs to the technical field of chemical engineering and pharmaceutical intermediate synthesis and relates to a method for preparing a styrene derivative from ionic liquid. The methodhas advantages that by adoption of the ionic liquid as a solvent, high reaction catalyzing efficiency is achieved; due to reusability of the ionic liquid, industrial production cost is saved, and theenvironment problem caused by traditional solvents can be solved helpfully.
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Paragraph 0032-0034
(2019/04/06)
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- Substituted styrene preparation method
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The invention belongs to the technical field of synthesis of chemical and medical intermediates, and relates to a substituted styrene preparation method, in particular to a method for preparing substituted styrene by using an ionic solution. In the method, the ionic solution is used as a solvent, and the reaction catalyzing efficiency is high. The ionic solution can be repeatedly used, industrialproduction cost is saved, and environment problems caused by a traditional solvent are solved favorably.
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Paragraph 0032-0034
(2019/02/26)
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- A method for the preparation of substituted styrene ion solution method
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The invention belongs to chemical and pharmaceutical intermediate synthesis technology field, relates to a process for preparing a substituted styrene ion solution method. The method takes the ionic liquid as solvent, reaction of high catalytic efficiency. The ionic liquid can be used repeatedly, save the industrialized production cost, and to facilitate the solution of the environmental problem of traditional solvent.
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Paragraph 0032; 0033; 0034
(2019/04/02)
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- Method for selective synthesis of cis-olefins and trans-olefins by semi-reduction of alcohol hydrogen supply palladium-catalyzed alkynes
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The invention provides a method for selective synthesis of cis-olefins and trans-olefins by semi-reduction of alcohol hydrogen supply palladium-catalyzed alkynes. The method comprises the following steps: performing alkyne reduction reaction with TEOA, NaOAc, a catalyst, alcohol and alkynes in an organic solvent and generating the cis-olefins after reaction; performing alkyne reduction reaction with a ligand, a catalyst, alcohol and alkynes in an organic solvent and generating the trans-olefins after reaction; a reactor for the reduction reaction is a sealed pressure-resistant reactor, the reduction reaction temperature is 120-150 DEG C, and the reduction reaction time is 20-48 hours; the dosage of the catalyst is 5-20 percent of the molar dosage of the alkynes, and the dosage of the alcohol is 10-100 times of the molar dosage of the alkynes; the dosage of R, R-DIPAMP is 0.5-5 times of the molar dosage of the alkynes. According to the method provided by the invention, a catalyst systemhas extremely-high chemical reaction and stereo-selectivity and can synthesize cis-olefin products or trans-olefin products with high yield; the catalyst system is good universality to a substrate, and the alkynes containing various functional groups can be efficiently subjected to the highly-selective reduction reactions.
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Paragraph 0203-0205
(2019/06/07)
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- Synthesis and Catalytic Applications of [N,N]-Pyrrole Ligands for the Regioselective Synthesis of Styrene Derivatives
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We report the synthesis of two [N,N]-donor ligands (5 a–b) containing a 2-chalcogenazoline as the structural motif. These compounds were synthesized from a common intermediate Fischer type aminocarbene complex (3). The palladium-complexes of these [N,N]-donor ligands were successfully used as catalytic precursors in the Mizoroki-Heck coupling reaction between aryl halides and methyl acrylate, styrene and ethylene. For methyl acrylates, high yields with TOF values between 0.6 and 5.5×105 h?1 were obtained. In the case of ethylene, we reached high regioselectivities to obtain a diversity of styrene derivatives under soft pressure conditions, with good values of TON and TOF. (Figure presented.).
- Hochberger-Roa, Frank,Cortés-Mendoza, Salvador,Gallardo-Rosas, David,Toscano, Ruben A.,Ortega-Alfaro, M. Carmen,López-Cortés, José G.
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p. 4055 - 4064
(2019/07/31)
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- Terminal Alkenes from Acrylic Acid Derivatives via Non-Oxidative Enzymatic Decarboxylation by Ferulic Acid Decarboxylases
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Fungal ferulic acid decarboxylases (FDCs) belong to the UbiD-family of enzymes and catalyse the reversible (de)carboxylation of cinnamic acid derivatives through the use of a prenylated flavin cofactor. The latter is synthesised by the flavin prenyltransferase UbiX. Herein, we demonstrate the applicability of FDC/UbiX expressing cells for both isolated enzyme and whole-cell biocatalysis. FDCs exhibit high activity with total turnover numbers (TTN) of up to 55000 and turnover frequency (TOF) of up to 370 min?1. Co-solvent compatibility studies revealed FDC's tolerance to some organic solvents up 20 % v/v. Using the in-vitro (de)carboxylase activity of holo-FDC as well as whole-cell biocatalysts, we performed a substrate profiling study of three FDCs, providing insights into structural determinants of activity. FDCs display broad substrate tolerance towards a wide range of acrylic acid derivatives bearing (hetero)cyclic or olefinic substituents at C3 affording conversions of up to >99 %. The synthetic utility of FDCs was demonstrated by a preparative-scale decarboxylation.
- Aleku, Godwin A.,Prause, Christoph,Bradshaw-Allen, Ruth T.,Plasch, Katharina,Glueck, Silvia M.,Bailey, Samuel S.,Payne, Karl A. P.,Parker, David A.,Faber, Kurt,Leys, David
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p. 3736 - 3745
(2018/08/03)
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- Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions
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Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing. The substituent effect on Am/Cm separating selectivity was also achieved, which could contribute to the development of new chromatographic materials for the separation of Am and Cm.
- Yang, Chu-Ting,Han, Jun,Liu, Jun,Li, Yi,Zhang, Fan,Yu, Hai-Zhu,Hu, Sheng,Wang, Xiaolin
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supporting information
p. 10324 - 10328
(2018/07/31)
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- Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes
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Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes are described. This redox neutral strategy offers an efficient approach to diverse biaryls, vinyl arenes and arylacetylenes. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the in situ formation of Ph3PAuIR (R = aryl, vinyl and alkynyl) species which is crucial for the activation of aryldiazonium salts.
- Akram, Manjur O.,Shinde, Popat S.,Chintawar, Chetan C.,Patil, Nitin T.
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supporting information
p. 2865 - 2869
(2018/05/03)
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- Interrogating Pd(II) Anion Metathesis Using a Bifunctional Chemical Probe: A Transmetalation Switch
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Ligand metathesis of Pd(II) complexes is mechanistically essential for cross-coupling. We present a study of halide→OH anion metathesis of (Ar)PdII complexes using vinylBPin as a bifunctional chemical probe with Pd(II)-dependent cross-coupling pathways. We identify the variables that profoundly impact this event and allow control to be leveraged. This then allows control of cross-coupling pathways via promotion or inhibition of organoboron transmetalation, leading to either Suzuki-Miyaura or Mizoroki-Heck products. We show how this transmetalation switch can be used to synthetic gain in a cascade cross-coupling/Diels-Alder reaction, delivering borylated or non-borylated carbocycles, including steroid-like scaffolds.
- Molloy, John J.,Seath, Ciaran P.,West, Matthew J.,McLaughlin, Calum,Fazakerley, Neal J.,Kennedy, Alan R.,Nelson, David J.,Watson, Allan J. B.
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supporting information
p. 126 - 130
(2018/01/17)
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- Model Guided Development of a Simple Catalytic Method for the Synthesis of Unsymmetrical Stilbenes by Sequential Heck Reactions of Aryl Bromides with Ethylene
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Stilbenes are important and useful structural moieties, but methods for their preparation typically possess numerous inefficiencies. Presented here is a methodology for the two-step, one pot preparation of unsymmetrical stilbenes via sequential Heck reactions. The first Heck reaction with ethylene gas was analysed as a function of temperature and pressure for electronically differentiated naphthyl bromides and model-aided reaction optimization was utilized to define the system. In addition, reactNMR was utilized to determine ethylene solubility in common organic solvents useful for Heck reactions. Finally, an optimized sequential Heck reaction process was developed and applied to a range of substrates allowing for efficient preparation of unsymmetrical stilbenes, including the natural antioxidant, pterostilbene. (Figure presented.).
- Barlow, Helen,Buser, Jonas Y.,Glauninger, Hendrik,Luciani, Carla V.,Martinelli, Joseph R.,Oram, Niall,Thompson-Van Hook, Nichole,Richardson, Jeffery
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supporting information
p. 2678 - 2690
(2018/06/04)
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- Enantioselective, Catalytic Vicinal Difluorination of Alkenes
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The enantioselective, catalytic vicinal difluorination of alkenes is reported by II/IIII catalysis using a novel, C2-symmetric resorcinol derivative. Catalyst turnover via in situ generation of an ArIIIIF2 species is enabled by Selectfluor oxidation and addition of an inexpensive HF–amine complex. The HF:amine ratio employed in this process provides a handle for regioselective orthogonality as a function of Br?nsted acidity. Selectivity reversal from the 1,1-difluorination pathway (geminal) to the desired 1,2-difluorination (vicinal) is disclosed (>20:1 in both directions). Validation with electron deficient styrenes facilitates generation of chiral bioisosteres of the venerable CF3 unit that is pervasive in drug discovery (20 examples, up to 94:06 e.r.). An achiral variant of the reaction is also presented using p-TolI (up to >95 % yield).
- Scheidt, Felix,Sch?fer, Michael,Sarie, Jér?me C.,Daniliuc, Constantin G.,Molloy, John J.,Gilmour, Ryan
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supporting information
p. 16431 - 16435
(2018/11/23)
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- Catalytic Geminal Difluorination of Styrenes for the Construction of Fluorine-rich Bioisosteres
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A geminal difluorination of alkenes based on I(I)/I(III) catalysis is disclosed, which is compatible with a range of electronically and substitutionally diverse styrenes (27 examples, up to 89% yield). Employing inexpensive p-TolI as the organocatalyst, turnover is enabled by Selectfluor-mediated oxidation to generate the ArIF2 species in situ. Extension to include α-substituted styrenes bearing fluorine-containing groups is disclosed and provides an expansive platform for the generation of fluorine-rich architectures.
- Scheidt, Felix,Neufeld, Jessica,Sch?fer, Michael,Thiehoff, Christian,Gilmour, Ryan
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supporting information
p. 8073 - 8076
(2019/01/04)
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- Fluorinated cyclopropanes: Synthesis and chemistry of the aryl α,β,β-trifluorocyclopropane motif
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A general route to aryl α,β,β-trifluorocyclopropanes is reported and aryl oxidation gave the corresponding α,β,β-trifluorocyclopropane carboxylic acid. Reactions of the corresponding amides with phenol/thiophenol resulted in HF elimination and then conjugate addition. The partially fluorinated cyclopropane has a similar lipophilicity to -CF3 despite three carbon atoms, and it emerges as a novel motif for drug discovery.
- Thomson, Connor J.,Zhang, Qingzhi,Al-Maharik, Nawaf,Bühl, Michael,Cordes, David B.,Slawin, Alexandra M. Z.,O'Hagan, David
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p. 8415 - 8418
(2018/08/04)
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- Deoxydehydration of vicinal diols and polyols catalyzed by pyridinium perrhenate salts
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Simple ammonium and pyridinium perrhenate salts were evaluated as catalysts for the deoxydehydration (DODH) of diols into alkenes. Pyridinium perrhenates were found to be effective catalysts at much lower temperatures than those in previous reports, outperforming primary, secondary, and tertiary ammonium salts, while quaternary ammonium salts are effectively inactive. The mechanism of reaction was studied computationally using DFT calculations which indicate that proton shuttling between the ion pair is intrinsic to the mechanism and that the reduction of rhenium by the phosphine occurs before the diol condensation.
- Morris, Danny S.,Van Rees, Karlotta,Curcio, Massimiliano,Cokoja, Mirza,Kühn, Fritz E.,Duarte, Fernanda,Love, Jason B.
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p. 5644 - 5649
(2017/12/07)
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- Phenylenevinylene oligomers by Mizoroki-Heck cross coupling reaction. Structural and optoelectronic characterization
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In order to study the effect of the molecular structure on the optical properties of totally trans-trans phenylenevinylene oligomers (OPVs), sixteen 1,4-distyrylbenzene derivatives (1a-i and 2a-g) functionalized with different electron-donating (ED) and electron-withdrawing (EW) groups were synthesized by the Mizoroki-Heck cross coupling reaction in moderate to good yields (40–95%). The implemented methodology, with a small modification previously reported by our group, allows obtaining the desired vinyl configuration as well as one novel OPV compound (1h). After structural characterization by several techniques (e.g. FTIR, 1H, 13C and Solid-State NMR), particular emphasis was placed upon the investigation of their optical properties by UV–vis and fluorescence spectroscopies. The results showed that, with only one exception, the ED and EW groups at the ends of OPV systems lead to a bathochromic shift. This effect is intensified with the introduction of methoxy groups on the central ring. Consistent with these, the HOMO-LUMO gaps (ΔE) decreases as the strength of ED and EW substituents increases. The ED and EW substituents also lead to a decrease in the Φf values. This contribution in the area of organic electronics can be used as a reference to better select the most appropriate technological application for each OPV and this can be extrapolated to their respective structurally analogous segmented polymer.
- Estrada, Sandra E.,Ochoa-Puentes, Cristian,Sierra, Cesar A.
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p. 448 - 457
(2016/12/30)
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- Carboxylation of styrenes with CBr4 and DMSO via cooperative photoredox and cobalt catalysis
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Cooperative photoredox and cobalt catalyzed carboxylation of styrenes with CBr4 to afford the corresponding α,β-unsaturated carboxylic acids has been realized through radical addition and Kornblum (DMSO) oxidation. DMSO serves as the oxidant, oxygen source and solvent under these photocatalytic conditions.
- Song, Cai-Xia,Chen, Ping,Tang, Yu
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p. 11233 - 11243
(2017/02/26)
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- Electrosynthesis of vinyl sulfones from alkenes and sulfonyl hydrazides mediated by KI: Аn electrochemical mechanistic study
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A variety of vinyl sulfones were prepared from alkenes and sulfonyl hydrazides via electrochemical oxidative sulfonylation. The reaction proceeds in an experimentally convenient undivided electrochemical cell equipped with graphite and iron electrodes employing KI as a redox catalyst and a supporting electrolyte. Applying extremely high current density up to 270 mA/cm2 permits rapid synthesis in a compact reactor and with small surface area electrodes. A possible reaction mechanism was proposed with the use of cyclic voltammetry. It is the combination of anodic and cathodic processes in this reaction that makes it possible to obtain products under mild conditions with yields from moderate to high.
- Terent'ev, Alexander O.,Mulina, Olga M.,Pirgach, Dmitry A.,Ilovaisky, Alexey I.,Syroeshkin, Mikhail A.,Kapustina, Nadezhda I.,Nikishin, Gennady I.
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supporting information
p. 6871 - 6879
(2017/11/06)
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- Oligo p-Phenylenevinylene Derivatives as Electron Transfer Matrices for UV-MALDI
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Phenylenevinylene oligomers (PVs) have outstanding photophysical characteristics for applications in the growing field of organic electronics. Yet, PVs are also versatile molecules, the optical and physicochemical properties of which can be tuned by manipulation of their structure. We report the synthesis, photophysical, and MS characterization of eight PV derivatives with potential value as electron transfer (ET) matrices for UV-MALDI. UV-vis analysis show the presence of strong characteristic absorption bands in the UV region and molar absorptivities at 355 nm similar or higher than those of traditional proton (CHCA) and ET (DCTB) MALDI matrices. Most of the PVs exhibit non-radiative quantum yields (φ) above 0.5, indicating favorable thermal decay. Ionization potential values (IP) for PVs, calculated by the Electron Propagator Theory (EPT), range from 6.88 to 7.96 eV, making these oligomers good candidates as matrices for ET ionization. LDI analysis of PVs shows only the presence of radical cations (M+.) in positive ion mode and absence of clusters, adducts, or protonated species; in addition, M+. threshold energies for PVs are lower than for DCTB. We also tested the performance of four selected PVs as ET MALDI matrices for analytes ranging from porphyrins and phthalocyanines to polyaromatic compounds. Two of the four PVs show S/N enhancement of 1961% to 304% in comparison to LDI, and laser energy thresholds from 0.17 μJ to 0.47 μJ compared to 0.58 μJ for DCTB. The use of PV matrices also results in lower LODs (low fmol range) whereas LDI LODs range from pmol to nmol. [Figure not available: see fulltext.].
- Castellanos-García, Laura J.,Agudelo, Brian Castro,Rosales, Hernando F.,Cely, Melissa,Ochoa-Puentes, Christian,Blanco-Tirado, Cristian,Sierra, Cesar A.,Combariza, Marianny Y.
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p. 2548 - 2560
(2017/12/12)
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- A highly efficient and recyclable Pd(PPh3)4/PEG-400 system for Stille cross-coupling reactions of organostannanes with aryl bromides
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Pd(PPh3)4 in PEG-400 is shown to be a highly efficient catalyst for the Stille cross-coupling reactions of various organotin compounds with aryl bromides. The reaction could be conducted at 80 °C using NaOAc as base, yielding a variety of biaryls, alkynes and alkenes in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether and the Pd(PPh3)4/PEG-400 system could be easily recycled and reused five times without any significant loss of activity.
- Huang, Xue,Yao, Fang,Wei, Ting,Cai, Mingzhong
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p. 547 - 550
(2017/10/03)
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- Switching the Cleavage Sites in Palladium on Carbon-Catalyzed Carbon-Carbon Bond Disconnection
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We have demonstrated a palladium on carbon-catalyzed approach to regioselectively alter the cleavage sites of the C-C bonds of cinnamaldehyde derivatives by a slight change in the reaction conditions in isopropanol under an O2 atmosphere. Styrene derivatives could be selectively formed by the addition of Na2CO3 in association with the dissociation of carbon monoxide, while benzaldehyde derivatives were generated by the addition of CuCl and morpholine instead of Na2CO3. (Chemical Equation Presented).
- Hattori, Tomohiro,Takakura, Ryoya,Ichikawa, Tomohiro,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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p. 2737 - 2743
(2016/04/26)
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- Mechanism of the Novel Prenylated Flavin-Containing Enzyme Ferulic Acid Decarboxylase Probed by Isotope Effects and Linear Free-Energy Relationships
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Ferulic acid decarboxylase from Saccharomyces cerevisiae catalyzes the decarboxylation of phenylacrylic acid to form styrene using a newly described prenylated flavin mononucleotide cofactor. A mechanism has been proposed, involving an unprecedented 1,3-dipolar cyclo-addition of the prenylated flavin with the α=β bond of the substrate that serves to activate the substrate toward decarboxylation. We measured a combination of secondary deuterium kinetic isotope effects (KIEs) at the α- and β-positions of phenylacrylic acid together with solvent deuterium KIEs. The solvent KIE is 3.3 on Vmax/KM but is close to unity on Vmax, indicating that proton transfer to the product occurs before the rate-determining step. The secondary KIEs are normal at both the α- and β-positions but vary in magnitude depending on whether the reaction is performed in H2O or D2O. In D2O, the enzyme catalyzed the exchange of deuterium into styrene; this reaction was dependent on the presence of bicarbonate. This observation implies that CO2 release must occur after protonation of the product. Further information was obtained from a linear free-energy analysis of the reaction through the use of a range of para- and meta-substituted phenylacrylic acids. Log(kcat/KM) for the reaction correlated well with the Hammett σ- parameter with p= -0.39 ± 0.03; r2 = 0.93. The negative p value and secondary isotope effects are consistent with the rate-determining step being the formation of styrene from the prenylated flavin-product adduct through a cyclo-elimination reaction.
- Ferguson, Kyle L.,Arunrattanamook, Nattapol,Marsh, E. Neil G.
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p. 2857 - 2863
(2016/07/16)
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- Application of Pd Nanoparticles Supported on Mesoporous Hollow Silica Nanospheres for the Efficient and Selective Semihydrogenation of Alkynes
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Herein, the preparation of a heterogeneous catalyst consisting of 1-2 nm sized Pd nanoparticles supported on amino-functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono- And disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over-reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.
- Verho, Oscar,Zheng, Haoquan,Gustafson, Karl P. J.,Nagendiran, Anuja,Zou, Xiaodong,B?ckvall, Jan-E.
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p. 773 - 778
(2016/03/05)
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- Oxidative trifluoromethylation and fluoroolefination of unactivated olefins
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Fluorine-containing organic compounds are gaining increasing importance in medicinal chemistry. Described herein is a mild and efficient method for the radical addition of olefins with TMSCF3 and TMSCF2R (R = COOEt or CF3) to deliver various α-trifluoromethylated ketones and α-fluoroolefinated ketones.
- Wu, Ye-Bin,Lu, Guo-Ping,Yuan, Tao,Xu, Zhu-Bing,Wan, Li,Cai, Chun
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supporting information
p. 13668 - 13670
(2016/11/29)
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- SQUALENE COMPOUNDS AS MODULATORS OF LDL-RECEPTOR EXPRESSION
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The present invention relates to compounds that modify low density lipoprotein receptor (LDLR) expression. The compounds have the structural formula I shown below: wherein m, R1, n, R2 and R3 are each as defined herein. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of diseases or disorders associated with elevated levels of low density lipoprotein cholesterol (LDL-C).
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Paragraph 0005; 0022
(2016/04/20)
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- Wittig Reactions of Trialkylphosphine-derived Ylides: New Directions and Applications in Organic Synthesis
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The development of semi-stabilized, stabilized, and functionalized ylides derived from short-chain trialkylphosphines in the Wittig-type olefination reactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy separation of water-soluble phosphine oxides. The development of a mild organocatalytic process for the Wittig reaction and extension toward the preparation of reporter stilbenes under biological conditions are also described. Applications toward the preparation of biologically active natural products and derivatives are discussed.
- McNulty, James,McLeod, David,Das, Priyabrata,Zepeda-Velázquez, Carlos
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p. 619 - 632
(2016/01/15)
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- Arylation of perfluoroalkyl vinyl sulfoxides via the Heck reaction
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Heck reactions of perfluoroalkyl vinyl sulfoxides with aryl iodides are studied and palladium(II) acetate is shown to be the most convenient catalyst for this process. New E-1-aryl-2-perfluoroalkylsulfinylethylenes are synthesized. In all cases, by-products without a perfluoroalkylsulfinyl group are formed.
- Sokolenko, Liubov V.,Yagupolskii, Yurii L.,Vlasenko, Yurii G.,Babichenko, Liudmila N.,Lipetskij, Volodimir O.,Anselmi, Elsa,Magnier, Emmanuel
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supporting information
p. 1259 - 1262
(2015/03/04)
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- Polyaniline-anchored palladium catalyst-mediated Mizoroki-Heck and Suzuki-Miyauraa reactions and one-pot Wittig-Heck and Wittig-Suzuki reactions
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A polyaniline-anchored palladium catalyst was prepared and screened for coupling reactions of aryl halides. The robust and recyclable catalyst was effective in Mizoroki-Heck and Suzuki-Miyaura reactions of aryl bromides and aryl iodides. The catalyst system was further employed for one-pot Wittig-Heck and Wittig-Suzuki combinations to build conjugated compounds in good conversions.
- Patel, Heta A.,Patel, Arun L.,Bedekar, Ashutosh V.
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