Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• clear further in this review. An overview of different possible setups for obtaining carboxylic acids is given in Scheme 6. Electrocarboxylation reactions can either be conducted with a sacrificial anode, like magnesium or aluminum, or with an inert anode, like platinum or carbon. Most research has been

• -butadiene in a two-compartment cell with a mercury cathode and a platinum anode, giving a mixture of mono- and dicarboxylic acids. CO2 bubbling through a catholyte solution of 1 wt % water in DMF, saturated with butadiene, yielded up to 50% of 3-hexenedioic acid [45], a result which unfortunately was

• electrocarboxylation of 1,3-butadiene (Table 1) are illustrated in Scheme 8. They are divided into three categories, with (a) the sacrificial anode dissolution, (b) the proton forming reactions and (c) the oxidations evolving other free cations. In case a stable platinum anode is used, a C5:C6:C10 product mixture is

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• -coupling of benzyl or alkyl halides with racemic secondary phosphines have been developed. These reactions were catalyzed by chiral platinum or ruthenium complexes. The enantioselectivity is based on a dynamic kinetic resolution. Upon reaction with the catalyst precursor containing a chiral ligand (L*), a

• isolated as their air-stable phosphine–borane complexes 12c, 37 [59][60]. The group of Glueck has reported a method for the asymmetric alkylation of racemic secondary phosphines 36b by means of a chiral platinum-based catalyst 39 (Scheme 12) [61]. The enhanced nucleophilicity at phosphorus of the platinum

• excesses were reported. As expected, a mechanistic study suggested that the major enantiomer of product was formed from the major diastereomer of the platinum–phosphido intermediate [63]. Glueck and co-workers also developed an analogous method for the tandem alkylation/arylation of primary phosphines on

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• by cyclic voltammetry using a potentiostat (Princeton Applied Research 263A) at a scan rate of 1 V/s in acetonitrile, with platinum as both working and auxiliary electrodes, and a saturated calomel reference electrode (KCl in methanol). Measurements were performed in acetonitrile using 0.1 M of

Self-assembly of metallosupramolecular rhombi from chiral concave 9,9’-spirobifluorene-derived bis(pyridine) ligands

• Rainer Hovorka,
• Sophie Hytteballe,
• Torsten Piehler,
• Georg Meyer-Eppler,
• Filip Topić,
• Kari Rissanen,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 432–441, doi:10.3762/bjoc.10.40

• a completely statistical fashion but rather proceeds with a preference for forming homochiral complexes for both palladium (Figure 2a,b) and platinum ions since the intensity of the signals of the homochiral assemblies is larger than expected from statistics. However, both diastereomers were found

• heterochiral one in both cases – the palladium and the platinum complexes and independent of the solvents we used. This corresponds to an amplification of the homochiral stereoisomers via self-recognition by a factor of approximately three. Although these NMR spectra already provide a very good proof for the

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• reaction to convert an aldehyde or ketone to an alkane by the use of hydrazine (H2N–NH2) and a base (OH− or alkoxide RO−) [1][2]. The reaction is illustrated in Scheme 1. It is described as a "homogeneous" reaction [3] because the platinum catalyst used initially is not included. The formal change of the W

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

• 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

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

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

• 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

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

• 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

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

• 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

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

• , 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• (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

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• . 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