Search results

Search for "platinum" in Full Text gives 194 result(s) in Beilstein Journal of Organic Chemistry.

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

  • Sebastian Krüger and
  • Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

Graphical Abstract
  • 1,2-migration and subsequent formation of cis-divinylcyclopropane 269 yielding bridged bicycle 270. Chung and coworkers [210] discovered a related reaction pattern using platinum(II) as the catalyst. Depending on the attached rests on enyne 276 both possible cycloheptadienes (bridged 277 or annulated
  • - and gold-catalyzed versions of tandem reactions involving a DVCPR. Tungsten, platinum and gold catalysed cycloisomerizations leading to a DVCPR. Reisman’s total synthesis of salvileucalin B, featuring an (undesired) vinylcyclopropyl carbaldehyde rearrangement. Studies on the divinylepoxide
PDF
Album
Review
Published 16 Jan 2014

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

  • Alexander O. Terent'ev,
  • Dmitry A. Borisov,
  • Vera A. Vil’ and
  • Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

Graphical Abstract
PDF
Album
Review
Published 08 Jan 2014

Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ3,2-benziodaoxol-3-one

  • Nico Santschi,
  • Roman C. Sarott,
  • Elisabeth Otth,
  • Reinhard Kissner and
  • Antonio Togni

Beilstein J. Org. Chem. 2014, 10, 1–6, doi:10.3762/bjoc.10.1

Graphical Abstract
  • the initial hypothesis that nitration may lead to a more positive reduction potential, cyclic voltammetry (CV) measurements were carried out. These experiments were conducted under an atmosphere of nitrogen in anhydrous MeCN with Bu4NBF4 (0.1 M) as supporting electrolyte. A platinum working electrode
  • Bu4NBF4, platinum electrode, scan rate = 0.1 V/s. Sample kinetic traces for the decomposition of 2 (green) and 3 (blue) to 4 and 5, respectively, upon reaction with p-TsOH in MeCN. Solid lines represent the average decay (kdecomp) based on 6 individual measurements and dashed lines are decays based on
PDF
Album
Supp Info
Full Research Paper
Published 02 Jan 2014

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

  • Phei Li Lau,
  • Ray W. K. Allen and
  • Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

Graphical Abstract
  • published literature utilising 4-iodoanisole and methyl acrylate in the presence of ruthenium- and platinum-complex catalysts, in which complete regioselectivity towards the trans-isomer was achieved [19]. Having obtained encouraging conversions in the 1 mm diameter reactor, it was decided to scale the
PDF
Album
Full Research Paper
Published 17 Dec 2013

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

  • Guillaume Moreira,
  • Laurence Charles,
  • Mohamed Major,
  • Florence Vacandio,
  • Yohann Guillaneuf,
  • Catherine Lefay and
  • Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

Graphical Abstract
  • a solvent. The aim of the study was to measure the redox potentials of the SG1 and LiCl/solvent and to conclude if a redox reaction could happen between these species. The redox potentials of SG1 and LiCl (4.5 wt %) in DMF and MeOH were then determined by cyclic voltammetry with a platinum electrode
  • regularly withdrawn and diluted in 20 mL of t-BuPh for analysis at 25 °C under air. The electrochemical experiments were conducted in a three-electrode glass cell. A glassy carbon disk electrode (1 cm2) and a platinum wire were used as the working and the counter electrodes, respectively. The potentials
PDF
Album
Full Research Paper
Published 06 Aug 2013

True and masked three-coordinate T-shaped platinum(II) intermediates

  • Manuel A. Ortuño,
  • Salvador Conejero and
  • Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

Graphical Abstract
  • , Spain 10.3762/bjoc.9.153 Abstract Although four-coordinate square-planar geometries, with a formally 16-electron counting, are absolutely dominant in isolated Pt(II) complexes, three-coordinate, 14-electron Pt(II) complexes are believed to be key intermediates in a number of platinum-mediated
  • . Moreover, recent experimental and theoretical reports are analyzed, which suggest the involvement of such intermediates in reaction mechanisms, particularly C–H bond-activation processes. Keywords: C–H bond activation; intermediate; platinum(II); reactive intermediates; three-coordinate; T-shaped; Review
  • platinum complex [Pt(SiMe2Ph)2(IPr)] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) shows a unique Y-shaped geometry in which the Si–Pt–Si angle is very acute (80.9°) and far from the ideal values for both trigonal-planar and T-shaped structures (Y1, Figure 3) [15]. Computations on non-sterically
PDF
Album
Review
Published 09 Jul 2013

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

  • Rahat Javaid,
  • Shin-ichiro Kawasaki,
  • Akira Suzuki and
  • Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

Graphical Abstract
  • thin (1–2 μm) palladium (Pd), platinum (Pt), and rhodium (Rh) layers by an electroless plating procedure [10][11]. These tubular reactors combined the merit of flow reaction processing with the catalytic properties of various metals. Unlike packed-bed catalysts, hollow tubular reactors can minimize the
PDF
Album
Supp Info
Full Research Paper
Published 14 Jun 2013

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

  • Sofia Telitel,
  • Frédéric Dumur,
  • Thomas Faury,
  • Bernadette Graff,
  • Mohamad-Ali Tehfe,
  • Didier Gigmes,
  • Jean-Pierre Fouassier and
  • Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

Graphical Abstract
  • procedure described in detail in [58][59]. Redox potentials The redox potentials were measured in acetonitrile by cyclic voltammetry with tetrabutylammonium hexafluorophosphate (98%) as a supporting electrolyte (0.1 M) (Voltalab 6 Radiometer; the working electrode was a platinum disk and the reference a
PDF
Album
Supp Info
Full Research Paper
Published 07 May 2013

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

  • Amaresh Mishra,
  • Elena Mena-Osteritz and
  • Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

Graphical Abstract
  • compartment cell (2 mL). The platinum working electrode consisted of a platinum wire sealed in a soft glass tube with a surface area of A = 0.785 mm2, which was polished down to 0.5 μm with Buehler polishing paste prior to use in order to obtain reproducible surfaces. The counter electrode consisted of a
  • platinum wire, and the reference electrode was an Ag/AgCl secondary electrode. All potentials were internally referenced to the ferrocene/ferricenium couple. Calculations. Full geometry optimizations were performed in the gas phase by using density functional theory (DFT) calculations based on the B3LYP
PDF
Album
Full Research Paper
Published 06 May 2013

A peptidic hydrogel that may behave as a “Trojan Horse”

  • Nicola Castellucci,
  • Giorgio Sartor,
  • Natalia Calonghi,
  • Carola Parolin,
  • Giuseppe Falini and
  • Claudia Tomasini

Beilstein J. Org. Chem. 2013, 9, 417–424, doi:10.3762/bjoc.9.44

Graphical Abstract
  • collected within the 2Θ range from 5° to 35° with a step size (Δ2Θ) of 0.02° and a counting time of 1200 s. Atomic absorption spectroscopy analysis: Elemental platinum concentrations in medium solutions were measured with a Perkin-Elmer Mod. AAnalyst 100 Absorption Spectrometer (Perkin-Elmer Co., Norwalk
  • , CT) equipped with a deuterium background corrector, Autosampler AS-72, graphite furnace Perkin-Elmer Mod. HGA-800. A Pt Lumina (Perkin-Elmer) hollow-cathode lamp was used. Ten microliters of sample was injected and the furnace was heated slowly to 2500 °C. The absorbance of atomized platinum was
PDF
Album
Full Research Paper
Published 22 Feb 2013

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

  • Cristina Tubaro,
  • Marco Baron,
  • Andrea Biffis and
  • Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

Graphical Abstract
  • (II) salts as catalyst [8][9][10]. Palladium complexes with N-heterocyclic carbene (NHC) ligands have since been showcased as highly efficient catalysts for this reaction [11][12][13][14]. Alternative catalytic systems based on salts or complexes of other noble metals, such as platinum [15][16][17
PDF
Album
Full Research Paper
Published 05 Feb 2013

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

  • Maddi Sridhar Reddy,
  • Nuligonda Thirupathi and
  • Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

Graphical Abstract
  • transition-metal catalysts (based on gold, mercury, platinum, silver, etc.), Brønsted acids and electrophilic iodine sources (I2, ICl, NIS) have been used for the transformation. If one of the partners in A3 coupling has any nucleophile for concomitant electrophilic cyclization on the alkyne group in the A3
PDF
Album
Supp Info
Full Research Paper
Published 28 Jan 2013

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

  • Carolin Regenbrecht and
  • Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

Graphical Abstract
  • trimerization protocol [14][15][16]. Usually, yields are in a moderate range (≤35%) [15] when the electrolysis is performed on platinum or graphite anodes in anhydrous and non-nucleophilic electrolytes [14]. Poor yields are caused by the low oxidation potential of the products and the preference for over
  • practical galvanostatic conditions using platinum sheets as electrode materials. Due to the large potential window and outstanding solubility for common conducting salts, ACN is among the standard solvents for electrochemical purposes [17]. However, the application of ACN in electrochemical processes is
  • and 23.3 mL PC; method B: 4.116 g TBABF4 and 20.7 mL PC) in an undivided standard electrolysis cell and stirred under argon for 5 min. At 20 °C a galvanostatic electrolysis with a current density of 16 mA cm−2 was performed on platinum foil as electrodes (2.2 cm × 3.2 cm). The polarity of electrodes
PDF
Album
Supp Info
Full Research Paper
Published 10 Oct 2012

Supramolecular hydrogels formed from poly(viologen) cross-linked with cyclodextrin dimers and their physical properties

  • Yoshinori Takashima,
  • Yang Yuting,
  • Miyuki Otsubo,
  • Hiroyasu Yamaguchi and
  • Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1594–1600, doi:10.3762/bjoc.8.182

Graphical Abstract
  • adding selenium or platinum complexes yields supramolecular assemblies of bis(molecular tube)s cross-linked with the β-CD dimer, which form nanofibers [12][13][14][15]. Moreover, mechanically linked polyrotaxane with the α-CD and poly(ethylene glycol) (PEG) produces a hydrogel material, which exhibits
PDF
Album
Supp Info
Full Research Paper
Published 20 Sep 2012

Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

  • Bo Leng,
  • Stephanie Chichetti,
  • Shun Su,
  • Aaron B. Beeler and
  • John A. Porco Jr.

Beilstein J. Org. Chem. 2012, 8, 1338–1343, doi:10.3762/bjoc.8.153

Graphical Abstract
  • reaction mixture was added tetrakis(acetonitrile)copper(I) hexafluorophosphate (1.7 mg, 0.005 mmol), and the reaction mixture was stirred at room temperature for 1 h. Platinum(II) chloride (1.2 mg, 0.005 mmol) was added and the reaction mixture was heated to 80 °C for 5 h. The reaction mixture was
PDF
Album
Supp Info
Full Research Paper
Published 20 Aug 2012

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

  • Stefanie Potratz,
  • Amaresh Mishra and
  • Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

Graphical Abstract
  • films, which were deposited on the platinum working electrode within 30 cycles, were investigated in monomer-free dichloromethane solution. The CVs indicated that only dimers of 12 and 13 were formed, which showed quasi-reversible oxidation waves at 0.28 V and 0.68 V versus Fc/Fc+, respectively
  • , corresponding to a divinyl-quaterthiophene unit in 12 and a quaterthiophene in 13. Electrochemical polymerization of 14 performed on a platinum working electrode in the range of −0.9 to 0.8 V versus Fc/Fc+ within 30 cycles is displayed in Figure 3 (monomer 14: red, polymerization: gray, polymer film: blue
  • respect to 9,10-diphenylanthracene (DPA, Φ = 0.9 in dichloromethane) [43]. Cyclic voltammetry experiments were performed with a computer-controlled EG&G PAR 273 potentiostat in a three-electrode single-compartment cell (2 mL). The platinum working electrode consisted of a platinum wire sealed in a soft
PDF
Album
Full Research Paper
Published 03 May 2012

Self-assembly of Ru4 and Ru8 assemblies by coordination using organometallic Ru(II)2 precursors: Synthesis, characterization and properties

  • Sankarasekaran Shanmugaraju,
  • Dipak Samanta and
  • Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

Graphical Abstract
  • solvents CH3CN or CH3OH. IR spectra were recorded on a Bruker ALPHA FT-IR spectrometer. Electronic absorption studies were carried out on a Perkin Elmer LAMBDA 750 UV–vis spectrophotometer. The electrochemical measurements were performed in a three-electrode system consisting of a platinum electrode, a
PDF
Album
Supp Info
Full Research Paper
Published 28 Feb 2012

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

  • Nicholas G. White and
  • Paul D. Beer

Beilstein J. Org. Chem. 2012, 8, 246–252, doi:10.3762/bjoc.8.25

Graphical Abstract
  • electrode, a platinum-wire auxiliary electrode and an Innovative Instruments, Inc. LF-2 leak-free silver/silver chloride reference electrode. A 0.50 mM ferrocene sample was used in order to check the reference electrode and internal resistance of the equipment. The electrolyte solution used in all
PDF
Album
Supp Info
Full Research Paper
Published 13 Feb 2012

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

  • Antonio Avellaneda,
  • Courtney A. Hollis,
  • Xin He and
  • Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

Graphical Abstract
  • . Cyclic voltammetry Cyclic voltammetry measurements were performed on a PAR Model 263A potentiostat under nitrogen. Measurements were recorded on 1 mM solutions in dichloromethane/0.1 M [(n-C4H9)4]NPF6] solution using a platinum working electrode, platinum wire auxiliary and pseudo-reference electrodes
PDF
Album
Supp Info
Full Research Paper
Published 11 Jan 2012

Sexithiophenes as efficient luminescence quenchers of quantum dots

  • Christopher R. Mason,
  • Yang Li,
  • Paul O’Brien,
  • Neil J. Findlay and
  • Peter J. Skabara

Beilstein J. Org. Chem. 2011, 7, 1722–1731, doi:10.3762/bjoc.7.202

Graphical Abstract
  • anhydrous CH2Cl2 or acetonitrile as the solvent, aqueous Ag/AgCl as the reference electrode and platinum wire and gold disk (or ITO glass for SEC) as the counter and working electrodes, respectively. All solutions were degassed (Ar) and, where relevant, were prepared so as to contain the substrate in
  • ITO glass, versus Ag/AgCl reference electrode, platinum wire as the counter electrode, TBAPF6 as the supporting electrolyte in CH3CN (0.1 M), scan rate 100 mV s−1. Absorption spectra in solution (dichloromethane) and solid state. UV–visible spectroelectrochemical measurements of 1b (left) and 2b
PDF
Album
Full Research Paper
Published 22 Dec 2011

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

  • Alicja Schlange,
  • Antonio Rodolfo dos Santos,
  • Ulrich Kunz and
  • Thomas Turek

Beilstein J. Org. Chem. 2011, 7, 1412–1420, doi:10.3762/bjoc.7.165

Graphical Abstract
  • preparation in a flow reactor which could be used at a large scale. Keywords: carbon nanotubes; continuous catalyst synthesis; direct electrical heating; flow reactors; fuel cell platinum catalyst; Introduction Batch processes represent the state of the art in catalyst preparation. One reason for employing
  • results. Most of the work is concerned with the precipitation of hydroxides, oxides or other hardly soluble metal compounds [12]. Platinum nanoparticles supported on conductive carbon materials such as carbon black or carbon nanotubes (CNTs) are commonly used as oxygen reduction reaction (ORR) catalysts
  • supported Pt catalyst and its electrochemical activities [16][17][18]. To overcome this challenge, further research on electrocatalyst development is a necessity. Generally, high metal content, small platinum cluster size, and uniform particle distribution over the support material are needed to enhance the
PDF
Album
Full Research Paper
Published 14 Oct 2011

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths

  • Ping He,
  • Stephen J. Haswell,
  • Paul D. I. Fletcher,
  • Stephen M. Kelly and
  • Andrew Mansfield

Beilstein J. Org. Chem. 2011, 7, 1150–1157, doi:10.3762/bjoc.7.133

Graphical Abstract
  • sealed within the Teflon® tube to form a flow Pd-monolith reactor system. Sample characterization Scanning electron microscopy (SEM) images were obtained by means of a Cambridge S360 scanning electron microscope operated at 20 kV. Each sample was sputter coated with a thin layer of gold–platinum
PDF
Album
Supp Info
Full Research Paper
Published 23 Aug 2011

A practical microreactor for electrochemistry in flow

  • Kevin Watts,
  • William Gattrell and
  • Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

Graphical Abstract
  • without any added electrolyte [4][5]. Atobe et al. constructed a thin layer flow cell from platinum and/or glassy carbon plates (3 × 3 cm), separated by adhesive tape (80 µm), with a space left in between to act as the channel, and the devices were sealed with epoxy resin [6]. They reported the self
  • platinum electrodes with a surface area of 45 mm2 were positioned with an inter-electrode gap of either 160 µm or 320 µm, and C–C bond forming reactions based on the electro-reductive coupling of activated olefins and benzyl bromide derivatives were reported. The best result obtained was a 98% formation of
  • the continuous synthesis of diaryliodonium compounds. A microflow electrochemical reactor made out of two aluminium bodies (50 mm diameter, 25 mm height) was manufactured. The electrodes are constructed of two PTFE plates (35 mm diameter, 4 mm height) onto which 0.1 mm platinum foil electrodes [16
PDF
Album
Video
Full Research Paper
Published 15 Aug 2011

Recent developments in gold-catalyzed cycloaddition reactions

  • Fernando López and
  • José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

Graphical Abstract
  • , cobalt, nickel or palladium catalysts [4]. In recent years, however, platinum and particularly gold complexes have also emerged as excellent catalysts for the promotion of novel types of cycloaddition reactions, usually involving non-activated unsaturated systems (e.g., alkynes, allenes, alkenes or 1,3
  • and reductive eliminations). Therefore, platinum(II) and particularly gold(I) or (III) complexes tend to activate alkynes, alkenes or allenes in a highly chemoselective manner; activation that opens interesting reaction pathways that usually involve carbocationic intermediates. Also very important is
  • cycloadditions involving zwitterionic intermediates similar to I have also been developed with other transition metal catalysts such as tungsten, rhodium or platinum [32][33][34][35]. In particular, important developments were recently achieved with platinum catalysts [36][37], including the first
PDF
Album
Review
Published 09 Aug 2011

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

  • Alexandre Pradal,
  • Chung-Meng Chao,
  • Patrick Y. Toullec and
  • Véronique Michelet

Beilstein J. Org. Chem. 2011, 7, 1021–1029, doi:10.3762/bjoc.7.116

Graphical Abstract
  • carbophilic complexes such as platinum or gold [16][17][18][19][20][21][22] that led to the formation of complex bicyclic and tricyclic compounds [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The first asymmetric version was described by Shibata’s group in 2005 in the presence of a
  • chiral iridium catalyst [41] (Scheme 1, reaction 2). We and others recently pursued the improvement and development of this enantioselective process, by employing platinum [42][43][44], rhodium [45] or gold [46][47][48] complexes. Following our previous work with chiral gold catalysts [46], we report a
  • % isolated yield respectively) resulting from 5-exo- and 6-endo cycloisomerization reactions [20][66]. Thus, the gold catalytic system cannot compete with the results obtained for the cyclizations of nitrogen-tethered enynes in the presence of iridium, platinum or rhodium catalysts [41][42][43][44][45]. The
PDF
Album
Supp Info
Full Research Paper
Published 26 Jul 2011
Other Beilstein-Institut Open Science Activities