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Phenylboronic Acid (phenylboronic + acid)
Selected AbstractsPhenylboronic Acid as a Mild and Efficient Catalyst for Biginelli Reaction.CHEMINFORM, Issue 47 2006Abdelmadjid Debache Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] In situ Generated Rhodium-Based Catalyst for Addition of Phenylboronic Acid to Aldehydes.CHEMINFORM, Issue 7 2006Murat Yigit Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF. [source] Nitrogen Ligands: The Transition Metal Catalyzed Reaction of Aryl Halides with Olefins (Mizoroki,Heck), Phenylboronic Acid (Suzuki Coupling) and Buchwald,Hartwig Amination, New Catalysts and Effect of Cocatalysts,Aryl Halide Activation.CHEMINFORM, Issue 2 2006Part 1. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation of an Amphiphilic Resin-Supported BINAP Ligand and Its Use for Rhodium-Catalyzed Asymmetric 1,4-Addition of Phenylboronic Acid in Water.CHEMINFORM, Issue 1 2005Yusuke Otomaru Abstract For Abstract see ChemInform Abstract in Full Text. [source] Kinetic Studies Prove High Catalytic Activity of a Diene,Rhodium Complex in 1,4-Addition of Phenylboronic Acid to ,,,-Unsaturated KetonesCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2006Asato Kina Abstract In the 1,4-addition of phenylboronic acid to ,,,-unsaturated ketones, [Rh(OH)(cod)]2 has a much higher catalytic activity than [Rh(OH)(binap)]2 (cod=1,5-cyclooctadiene, binap=2,2,-bis(diphenylphosphanyl)-1,1,-binaphthyl). Kinetic studies revealed that the rate-determining transmetalation step in the catalytic cycle has a large rate constant when [Rh(OH)(cod)]2 is used. [source] Iridium-Catalyzed [3 + 2] Annulation of 1,3-Dienes with ortho-Carbonylated Phenylboronic Acids.CHEMINFORM, Issue 42 20072-Addition., A Catalyzed Process Involving Regioselective Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Ratiometric Fluorescence Sensing of Fluoride Ions by an Asymmetric Bidentate Receptor Containing a Boronic Acid and Imidazolium GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2009Zhaochao Xu Abstract The synthesis of the first examples of anion receptors that utilize boron,fluoride interactions and (C,H)+···F, -type ionic hydrogen-bond interactions in the binding of F ions is reported herein. o -, m -, and p -Phenylboronic acids were linked to naphthoimidazolium through a methylene group. On the basis of fluorescence and 19F NMR studies, we have confirmed that the addition of fluoride to a boron center occurs prior to the formation of (C,H)+···F, -type ionic hydrogen bond with the imidazolium moiety. More importantly, these investigations have demonstrated that only the receptor bearing the ortho -directed boron and imidazolium exhibits enhanced fluoride binding. The increased binding ability of the asymmetric bidentate receptor of ortho -boronic acid and imidazolium towards F, enables it to sense fluoride ions in a 95:5 CH3CN/HEPES aqueous solution. The fluorescence responses to different anions were also explored; the ortho -boron-imidazolium receptor displayed ratiometric fluorescence changes and a high selectivity towards fluoride ions over other anions (Cl,, Br,, CH3CO2,, HSO4,, and H2PO4,).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] ChemInform Abstract: Rh(I)-Catalyzed Reaction of 2-(Chloromethyl)phenylboronic Acids and Alkynes Leading to Indenes.CHEMINFORM, Issue 47 2008Masaki Miyamoto Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Molecular recognition of sugars by lanthanide (III) complexes of a conjugate of N, N -bis[2-[bis[2-(1, 1-dimethylethoxy)-2-oxoethyl]amino]ethyl]glycine and phenylboronic acidCONTRAST MEDIA & MOLECULAR IMAGING, Issue 4 2007Elisa Battistini Abstract A novel conjugate of phenylboronic acid and an Ln(DTPA) derivative, in which the central acetate pendant arm was replaced by the methylamide of L -lysine, was synthesized and characterized. The results of a fit of variable 17O NMR data and a 1H NMRD profile show that the water residence lifetime of the Gd(III) complex (150,ns) is shorter than that of the parent compound Gd(DTPA)2, (303,ns). Furthermore, the data suggest that several water molecules in the second coordination sphere of Gd(III) contribute to the relaxivity of the conjugate. The Ln(III) complexes of this conjugate are highly suitable for molecular recognition of sugars. The interaction with various sugars was investigated by 11B NMR spectroscopy. Thanks to the thiourea function that links the phenylboronic acid targeting vector with the DTPA derivative, the interactions are stronger than that of phenylboronic acid itself. In particular, the interaction with N -propylfructosamine, a model for the glucose residue in glycated human serum albumin (HSA), is very strong. Unfortunately, the complex also shows a rather strong interaction with hexose-free HSA (KA,=,705,±,300). Copyright © 2007 John Wiley & Sons, Ltd. [source] Boron,Nitrogen Adducts of 1,3,5-Triaza-7-phosphaadamantane (PTA): Synthesis, Reactivity, and Molecular StructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2006Brian J. Frost Abstract Addition of BH3 to 1,3,5-triaza-7-phosphaadamantane (PTA) leads to the formation of the first coordination complex of PTA in which a nitrogen and not the phosphorus of PTA is involved in the bonding. Multinuclear NMR spectroscopy, X-ray crystallography, and computational chemistry are utilized in the characterization of the products. Crystal structures of PTA,BH3 (1) and O=PTA,BH3 (2) adducts are described. In addition a coordination polymer, [CpRu(PTA)2Cl(Ph3B3O3)]n (3), resulting from Lewis acid,base adduct formation between the PTA ligands of CpRu(PTA)2Cl and the product of the cyclocondensation of phenylboronic acid is described. The polymeric compound 3 was also characterized by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Towards Selective Recognition of Sialic Acid Through Simultaneous Binding to Its cis -Diol and Carboxylate FunctionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010Martín Regueiro-Figueroa Abstract A series of receptors containing phenylboronic acid and urea or thiourea units have been designed for simultaneous recognition of the cis -diol and carboxylate functions of sialic acids, which are known to be overexpressed on the surfaces of tumor cells. The interaction of the receptors with 5-acetylneuraminic acid (Neu5Ac) and 2-,- O -methyl Neu5Ac (MeNeu5Ac) in DMSO solution has been investigated bymeans of spectrophotometric titrations and 1H, 13C, and 11B NMR spectroscopy. Additionally, we have also investigated the binding of these receptors with competing monosaccharides such as D -(+)-glucose, D -fructose, methyl ,- D -galactoside, and methyl ,- D -mannoside. Our results show that 2-{[3-(4-nitrophenyl)thioureido]methyl}phenylboronic acid (3a) recognizes both Neu5Ac and MeNeu5Ac with good selectivity with regard to the remaining monosaccharides investigated. DFT calculations performed at the B3LYP/6-31G(d) level show that this selectivity is due to a cooperative two-site binding of Neu5Ac through 1) ester formation by interaction at the phenylboronic acid function of the receptor and 2) hydrogen-bond interaction between the thiourea moiety and the carboxylate group of Neu5Ac. Compound 3a can therefore be considered a promising synthon for the design of contrast agents for magnetic resonance imaging of tumors. In contrast, the analogue of 3a containing a urea moiety , compound 3b , displays strong binding to all monosaccharides investigated, due to two-site binding through interaction on the phenylboronic acid function of the receptor and a hydrogen-bond interaction between the urea moiety and the sugar hydroxy groups. [source] Very Fast Suzuki,Miyaura Reaction Catalyzed by Pd(OAc)2 under Aerobic Conditions at Room Temperature in EGME/H2OEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2009Alessandro Del Zotto Abstract The results of a ligand-free Pd(OAc)2 -catalyzed Suzuki,Miyaura C,C coupling performed at room temperature under aerobic conditions are presented. It was found that the use of an ethylene glycol monomethyl ether/H2O mixture as the solvent resulted in very rapid reactions of aryl bromides with arylboronic acids. As a matter of fact, under optimized conditions, some substrates were converted quantitatively in less than 1 min with exceptionally high TOF values. For example, the reaction between 4-methoxyphenylboronic acid and bromobenzene afforded 4-methoxybiphenyl in 30 s with TOF = 180000 h,1. Furthermore, the reaction tolerates a wide range of functional groups and can be successfully applied to heteroaryl bromides such as 2-bromopyridine and 5-bromopyrimidine. Interestingly, also an activated aryl chloride such as 1-chloro-4-nitrobenzene reacted quantitatively with phenylboronic acid at 373 K. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A Study of the Stereochemical Course of , -Oxygen Elimination with a Rhodium(I) ComplexHELVETICA CHIMICA ACTA, Issue 12 2002Masahiro Murakami The stereochemical course of , -oxygen elimination of an organorhodium(I) complex was investigated through the Rh-catalyzed addition of phenylboronic acid to a chiral propargyl acetate to produce an allene. The degree of chirality transfer suggests that the , -oxygen elimination takes place in both syn and anti modes. [source] Dynamically Restructuring Hydrogel Networks Formed with Reversible Covalent Crosslinks,ADVANCED MATERIALS, Issue 18 2007C. Roberts Dynamically restructuring hydrogel networks are formed from two water-soluble polymers by functionalization with phenylboronic acid (PBA) and salicylhydroxamic acid (SHA) moieties that interact through pH-sensitive and reversible covalent crosslinks (see figure). The networks can be tuned to display a wide range of pH-responsive properties, which can potentially be exploited for drug delivery systems in biological environments where similar acidic changes occur. [source] Resorcin[4]arene-Derived Mono- and Diphosphines in Suzuki Cross-CouplingADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Hani El Moll Abstract Three resorcin[4]arene cavitands (1,3) having either one or two resorcinolic C-2 atoms substituted by a CH2PPh2 podand arm were assessed in the Suzuki arylation of aryl bromides with phenylboronic acid. Using P:Pd ratios of 2:1 and operating in dioxane at 100,°C with a catalyst loading of 0.001,mol% resulted in highly efficient catalytic systems. For example, TOFs up to 34570 mol(converted ArBr),mol(Pd),1,h,1 were obtained with the proximally-disubstituted cavitand 3 when using 4-bromotoluene as substrate. The performance was shown to vary in the following order: monophosphine 1 "Click" Polymer-Supported Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions under Ambient ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Cátia Ornelas Abstract Complexation of palladium(II) acetate [Pd(OAc)2] or dipotassium tetrachloropalladate [K2PdCl4] to "click" polymers functionalized with phenyl, ferrocenyl and sodium sulfonate groups gave polymeric palladium(II)-triazolyl complexes that were reduced to "click" polymer-stabilized palladium nanoparticles (PdNPs). Transmission electron microscopy (TEM) showed that reduction using sodium borohydride (NaBH4) produced PdNPs in the 1,3,nm range of diameters depending on the nature of the functional group, whereas slow reduction using methanol yielded PdNPs in the 22,25,nm range. The most active of these PdNPs (0.01% mol Pd), stabilized by poly(ferrocenyltriazolylmethyl)styrene, catalyzed the hydrogenation of styrene at 25,°C and 1 atm hydrogen, with turnover numbers (TONs) of 200,000. When stabilized by the water-soluble poly(sodium sulfonate-triazolylmethyl)styrene, the PdNPs (0.01% mol Pd) catalyze the Suzuki,Miyaura coupling between iodobenzene (PhI) and phenylboronic acid [PhB(OH)2] in water/ethanol (H2O/EtOH) at 25,°C with TONs of 8,200. This high catalytic activity is comparable to that obtained with "click" dendrimer-stabilized PdNPs under ambient conditions. [source] Iodine-Catalyzed Suzuki,Miyaura Coupling Performed in AirADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Jincheng Mao Abstract Suzuki-type coupling reactions can be performed directly in air using a catalytic system composed of iodine, potassium carbonate, and polyethylene glycol 400 (I2/K2CO3/PEG-400). Iodine was found to be an effective additive for accelerating these couplings. The methodology is also suitable for the coupling of (E)- , -bromostyene with phenylboronic acid, with retention of the double bond geometry. [source] 2-Aryl-4-azido-3-(bromo/iodo)quinolines as substrates for the synthesis of primary 4-amino-2,3-disubstituted quinoline derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2008Malose J. Mphahlele Staudinger reaction of the 2-aryl-4-azido-3-bromoquinolines and 2-aryl-4-azido-3-iodoquinolines with triphenyl phosphine in refluxing tetrahydrofuran afforded series of 2-aryl-3-halogeno-4-(triphenylphosphoranylideneamino)quinolines. The latter were, in turn, hydrolyzed to the corresponding primary 4-amino-2-aryl-3-(bromo/iodo)quinolines using 80% acetic acid under reflux. Tetrakis(triphenylphosphine)-palladium(O)-catalyzed Suzuki reaction of the 2-aryl-3-iodo-4-(triphenylphosphoranylideneamino)-quinolines with phenylboronic acid in dimethyl formamide in the presence of 2 M K2CO3 followed by hydrolysis of the incipient 2,3-diaryl-4-(triphenylphosphoranylideneamino)quinolines with 80% acetic acid afforded the 4-amino-2,3-diarylquinolines. [source] Thin semitransparent gels containing phenylboronic acid: porosity, optical response and permeability for sugarsJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2008Alexander E. Ivanov Abstract Radical copolymerization of acrylamide (Am) (90,mol%) with N -acryloyl- m -aminophenylboronic acid (NAAPBA) (10,mol%) carried out on the surface of glass slides in aqueous solution and in the absence of chemical cross-linkers, resulted in the formation of thin semitransparent gels. The phenylboronic acid (PBA) ligand density was ca. 160,µmol/ml gel. The gels exhibited a macroporous structure and displayed optical response to sucrose, lactose, glucose and fructose in 50,mM sodium phosphate buffer, in the pH range from 6.5 to 7.5. The response was fairly reversible and linearly depended on glucose concentration in the wide concentration range from 1 to 60,mM at pH 7.3. The character of response was explained by the balance of two competing equilibrium processes: binding of glucose to phenylboronate anions and binary hydrophobic interactions of neutral PBA groups. The apparent diffusion coefficient of glucose in the gels was ca. 2.5,×,10,7,cm2/s. A freshly prepared gel can be used daily for at least 1 month without changes in sensitivity. Autoclaving (121°C, 1.2 bar, 10,min) allows for the gels sterilization, which is important for their use as glucose sensors in fermentation processes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Glucose-sensitive holographic sensors,JOURNAL OF MOLECULAR RECOGNITION, Issue 3 2004S. Kabilan Abstract Holographic sensors for monitoring glucose were fabricated from hydrogel films containing chemical ligands based on phenylboronic acid. The films were transformed into reflection holograms using a diffusion method coupled with exposure to laser light. The diffraction wavelength of the holograms was used to monitor the swelling of the hydrogel film in the presence of glucose. Fully reversible changes in diffraction wavelength were demonstrated, highlighting the potential for using these holograms as glucose sensors. Copyright © 2004 John Wiley & Sons, Ltd. [source] Application of an enhanced luminol chemiluminescence reaction using 4-[4,5-di(2-pyridyl)-1H -imidazol-2-yl]phenylboronic acid to photographic detection of horseradish peroxidase on a membraneLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2001Naotaka Kuroda Abstract Photographic detection of horseradish peroxidase (HRP) on a membrane by the luminol,hydrogen peroxide,HRP chemiluminescence reaction using 4-[4,5-di(2-pyridyl)-1H -imidazol-2-yl]phenylboronic acid (DPPA) as an enhancer is described. The method is based on the long-lived chemiluminescence emission obtained by using DPPA. Under the optimum conditions, as little as 0.10,ng (ca. 2.3 fmol) and 0.20,ng (ca. 4.6 fmol) per spot of HRP on a membrane were detected as visible spots with exposure time of 60 and 10,min, respectively, by using an instant photographic film and a camera luminometer. The proposed method was highly sensitive and was successfully applied to the detection of HRP conjugates as an alternative to the colorimetric method using a chromogenic substrate in a commercially available assay kit of Western blotting. Copyright © 2001 John Wiley & Sons, Ltd. [source] New route to synthesis of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross-coupling reactionsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009Feyyaz Durap Abstract Herein we report a new method for the synthesis and characterization of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP-stabilized palladium(0) nanoclusters with a particle size of 4.5 ± 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 °C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV,vis, and XRD techniques. The PVP-stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP-stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd. [source] Water-soluble 2-arylnaphthoxazole-derived palladium (II) complexes as phosphine-free catalysts for the Suzuki reaction in aqueous solventAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2008Hong Li Abstract Two water-soluble palladium (II) complexes 2 and 4 have been synthesized from easily available 2-arylnaphthoxazole derivatives. They were successfully applied to the Suzuki coupling of aryl bromides with phenylboronic acid in water at 100 °C under phosphine-free conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Metal-Free and PdII -Promoted [2+3] Cycloadditions of a Cyclic Nitrone to Phthalonitriles: Syntheses of Oxadiazolines as well as Phthalamide,PdII and Dihydropyrrolyl-iminoisoindolinone,PdII Complexes with High Catalytic Activity in Suzuki,Miyaura Cross-Coupling ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2008Jamal Lasri Dr. Abstract The previously unknown reactions between phthalonitriles, 1,2-(CN)2(C6)R1R2R3R41 (1,a, R1=R2=R3=R4=H; 1,b, R1=R2=R4=H, R3=CH3; 1,c, R1=R4=H, R2=R3=Cl; 1,d, R1=R2=R3=R4=Cl; 1,e, R1=R2=R3=R4=F), and a cyclic nitrone, ,O+NCHCH2CH2CMe22, proceed under heating in a sealed tube to give phthalimides 3, 2-oxadiazolyl-benzonitriles 4 or ortho -bis(oxadiazolyl)tetrafluorobenzene 4,e,. In the presence of palladium(II) chloride, phthalonitriles 1 react with 2 at room temperature, to give bis(pyrrolidin-2-ylidene)phthalamide PdII complexes 5 via metal-promoted rupture of the NO bond of the oxadiazoline ring. The ketoimine ligands thus generated can be liberated from the metal by displacement with a diphosphine. Although the first [2+3] cycloaddition of 2 to 1 can occur in the absence of the metal to give the mono-cycloadducts 4, the second [2+3] coupling at the still-unreacted cyano group requires its activation by coordination to PdII, affording complexes 6 containing two ligated oxadiazolyl-benzonitriles. These ligands undergo either i) further cycloaddition with 2 to afford ultimately (upon rearrangement) the bis(pyrrolidinylidene)phthalamide complexes 5 or ii) NO bond cleavage in the oxadiazoline ring with intramolecular attack of the imine nitrogen on the cyano carbon and bridging to a second PdII center to afford dimeric palladium(II) complexes 7, with chloride bridges, that bear a dihydropyrrolyl-iminoisoindolinone, a new type of ligand. The compounds were characterized by IR, 1H, and 13C,NMR spectroscopy, ESI MS or FAB+ MS, elemental analyses and, in the case of 4,c, 5,a, 5,c, and 7,c, also by X-ray diffraction analysis. Complexes 5,a and 7,c show high catalytic activity for the Suzuki,Miyaura cross-coupling reaction of bromobenzene and phenylboronic acid and give biphenyl in high yields with turnover frequencies (TOFs) of up to 9.0×105,h,1. [source] Analysis of Dopamine and Tyrosinase Activity on Ion-Sensitive Field-Effect Transistor (ISFET) DevicesCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2007Ronit Freeman Abstract Dopamine (1) and tyrosinase (TR) activities were analyzed by using chemically modified ion-sensitive field-effect transistor (ISFET) devices. In one configuration, a phenylboronic acid functionalized ISFET was used to analyze 1 or TR. The formation of the boronate,1 complex on the surface of the gate altered the electrical potential associated with the gate, and thus enabled 1 to be analyzed with a detection limit of 7×10,5,M. Similarly, the TR-induced formation of 1, and its association with the boronic acid ligand allowed a quantitative assay of TR to be performed. In another configuration, the surface of the ISFET gate was modified with tyramine or 1 to form functional surfaces for analyzing TR activities. The TR-induced oxidation of the tyramine- or 1 -functionalized ISFETs resulted in the formation of the redox-active dopaquinone units. The control of the gate potential by the redox-active dopaquinone units allowed a quantitative assay of TR to be performed. The dopaquinone-functionalized ISFETs could be regenerated to give the 1 -modified sensing devices by treatment with ascorbic acid. [source] Kinetic Studies Prove High Catalytic Activity of a Diene,Rhodium Complex in 1,4-Addition of Phenylboronic Acid to ,,,-Unsaturated KetonesCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2006Asato Kina Abstract In the 1,4-addition of phenylboronic acid to ,,,-unsaturated ketones, [Rh(OH)(cod)]2 has a much higher catalytic activity than [Rh(OH)(binap)]2 (cod=1,5-cyclooctadiene, binap=2,2,-bis(diphenylphosphanyl)-1,1,-binaphthyl). Kinetic studies revealed that the rate-determining transmetalation step in the catalytic cycle has a large rate constant when [Rh(OH)(cod)]2 is used. [source] Conversion of Cellulose to Hexitols Catalyzed by Ionic Liquid-Stabilized Ruthenium Nanoparticles and a Reversible Binding AgentCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 1 2010Yinghuai Zhu Dr. A reversible cellulose binding agent, 1-(4,-(4,,-(2,,,-boronobenzyl)piperazinyl)-2,-butenyl)-3- n -butylimidazolium chloride 1, is synthesized by reacting 2-((4,-allylpiperazinyl)methyl) phenylboronic acid with 3-allyl-1- n -butylimidazolium chloride. 1 is miscible with ionic liquids, and when combined with Ru nanoparticles as a catalyst, cellulose can be converted to polyols under mild conditions. The catalyst can be recycled with sustained activity. [source] Pd on Porous Glass: A Versatile and Easily Recyclable Catalyst for Suzuki and Heck ReactionsCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 4 2008Christine Schmöger Abstract The catalytic activity of Pd supported on porous glass was studied for both Suzuki and Heck reactions under aerobic conditions, with particular focus on the Suzuki coupling. The reactions were carried out in water under microwave irradiation. The effects of the catalyst preparation process (calcination time and temperature), as well as the base, substrate, and boron compound used on the coupling reaction were investigated in relation to the reusability of the catalyst. Various bases promote the Suzuki coupling of phenylboronic acid with bromophenol very effectively resulting in quantitative conversion and excellent selectivity for the coupling product. However, most bases lead to deactivation of the catalyst after the first reaction cycle and the catalyst must be reactivated before reuse. Therefore, excellent conversions and selectivities for individual reactions are not sufficient to conclude if the chosen conditions are suitable for a given reaction, but results from recycling studies have to be considered also. [source] Concave Pyridines for Bifunctional Acid,Base Catalysis,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2007Timo Liebig Abstract Two bifunctional concave acid,base catalysts, 1 and 2, have been synthesized starting from 2,6-dibromopyridine (9) and 2,6-bis(,-alkenyloxy)phenylboronic acids 8 and 10 which end up as bridgeheads in final bimacrocycles 1 and 2. One bridgehead contained an additional substituent in the 4-position. The respective protected 4-hydroxymethyl-substituted phenylboronic acids 8 were synthesized from 4-bromo-3,5-dihydroxybenzoic acid (3) in five steps. 4-Unsubstituted boronic acid 10 and 4-substituted boronic acid 8 were then attached to 9 by subsequent Suzuki couplings to give tetra-,-alkenes 12. By ring-closing metathesis of 12, bimacrocyclic dienes 13 and 17 were formed. After deprotection of the 4-hydroxymethyl group of one bridgehead, a 3-hydroxybenzoate was coupled to 14 to give ester 15 which gave bifunctional acid,base catalyst 1 upon hydrolysis. Analogously, homologue 2 was synthesized, but before coupling the bimacrocycle to the benzoate, tetraene 14 was hydrogenated to 18. Acidic and basic centers in 1 (49,% from 9) and 2 (19,% from 9) are at least 5 Å apart.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Hydrophilic functionalization of syndiotactic polystyrene via a combination of electrophilic bromination and Suzuki,Miyaura reactionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2010Jihoon Shin Abstract Postfunctionalization of high-molecular-weight syndiotactic polystyrene (sPS) was achieved via combination of electrophilic bromination at the para-position of the polymer aromatic ring and subsequent Suzuki,Miyaura cross-coupling reactions with functionalized phenylboronic acids. The concentration of brominated styrene repeating unit in sPS was conveniently controlled by changing the ratio of added bromine relative to the polymer repeating unit. Brominated sPS (8.5 mol %) was converted quantitatively to other polar functional groups via Suzuki,Miyaura cross-coupling reactions with various functional group-substituted phenylboronic acids. The surface properties of functionalized sPS were studied by measuring water contact angles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4335,4343, 2010 [source]
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