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Search for "metal complexes" in Full Text gives 261 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

  • Tommaso Pecchioli,
  • Manoj Kumar Muthyala,
  • Rainer Haag and
  • Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

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  • properties. Hyperbranched polymers like polytriallylsilane or polyglycerol have been used in a wide range of transformations including aldol condensations [22], Suzuki cross-couplings [23] and Diels–Alder reactions [24], to name a few, with metal complexes as catalytically active principle. The advent of
  • organocatalysis has allowed for selective C–C bond formation by using small organic molecules [25][26][27][28][29][30][31]. In contrast to metal complexes, chiral or achiral organocatalysts are easily attached on supports. They do not suffer from metal leaching and they can be reused more readily [32][33][34][35
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Published 12 May 2015

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

  • Christian Benkhäuser and
  • Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

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  • social self-sorting manner as evidenced by NMR spectroscopy and mass spectrometry. Keywords: metal complexes; multivalency; self-assembly; self-sorting; supramolecular chemistry; Tröger's base; Introduction Self-assembly of defined aggregates from multicomponent mixtures through self-sorting effects
  • cage-like homoleptic metal complexes is (almost) prevented when they are mixed with a suitable transition metal ion. As the metal ions we chose copper(I) ions which prefer a tetrahedral coordination sphere by two chelating ligands with N-donor centers such as 2,2'-bipyridines or 1,10-phenanthrolines
  • characterization of the metal complexes: [Cu(H3CCN)4]BF4 (6.3 mg, 20 µmol) were dissolved in DMSO-d6 (1 mL). This solution (500 µL) were added to (rac)-1 (4.26 mg, 10 µmol) and the remaining 500 µL of the solution were added to 2 (4.34 mg, 10 µmol), respectively. The resulting solutions were characterized by NMR
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Published 08 May 2015

TTFs nonsymmetrically fused with alkylthiophenic moieties

  • Rafaela A. L. Silva,
  • Bruno J. C. Vieira,
  • Marta M. Andrade,
  • Isabel C. Santos,
  • Sandra Rabaça,
  • Dulce Belo and
  • Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

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  • derivatives have been reported in the last 40 years and many have been at the basis of several conducting, superconducting and other important electronic materials [2][3][4][5][6]. Bisdithiolene–transition metal complexes with square planar structures can be seen as inorganic TTF analogues, in which a
  • transition metal replaces the central double bond. They have similar frontier orbitals to TTF and have been also at the basis of several electronic materials [7]. An additional connection between the TTF derivatives and the bisdithiolene–transition metal complexes was recently provided by complexes with
  • converted to transition metal complexes based on extended thiophene/TTF-fused dithiolene ligands. They were obtained by cross-coupling reactions between alkylated thio and oxo compounds. The incorporation of these alkyl groups in the thiophenic ring is expected to increase the solubility of these TTFs and
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Published 05 May 2015

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

  • Martin Weiser,
  • Sergej Hermann,
  • Alexander Penner and
  • Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

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  • light sources, the research field of photoredox catalysis has tremendously grown over the past decade [1][2][3][4][5][6][7]. Transition metal complexes, mainly [Ru(bpy)3]2+ [7], were most often used as photocatalysts, whereas the potential of organic compounds and dyes has not yet been fully exploited
  • their potential and versatile applicability in chemical syntheses. Their non-photochemical counterparts require acids, bases or transition metal complexes as catalysts [10]. The first examples of photochemical olefin aminations were reported by Cookson et al. [11] and Kawanisi et al. [12] in the 1960s
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Published 27 Apr 2015

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

  • Igor B. Krylov,
  • Vera A. Vil’ and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

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  • the hydrogen transfer catalyzed by transition metal complexes. In these reactions, compounds with a double bond or a C–Hal bond act as oxidants (hydrogen acceptors). Examples of these reactions with aldehydes or primary alcohols as C–H reagents are given in Table 2. Crotononitrile, acetone, and benzyl
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Published 20 Jan 2015

An improved procedure for the preparation of Ru(bpz)3(PF6)2 via a high-yielding synthesis of 2,2’-bipyrazine

  • Danielle M. Schultz,
  • James W. Sawicki and
  • Tehshik P. Yoon

Beilstein J. Org. Chem. 2015, 11, 61–65, doi:10.3762/bjoc.11.9

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  • couplings [13][14], and photooxygenation reactions [15][16]. Similarly, Zheng has reported oxidatively initiated indole synthesis [17] and [3 + 2] cycloaddition [18][19] reactions using photocatalyst 2. Finally, a variety of transition metal complexes bearing bipyrazyl ligands have been prepared and
  • of bpz. An improved synthesis of this ligand would be useful both in the context of the growing interest in photoredox catalysis as well as other organometallic and inorganic applications of bpz-supported transition metal complexes. Our optimization studies for the reductive coupling of 2
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Published 14 Jan 2015

A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1’-binaphthalene-2,2’-diamines (BINAMs)

  • Youhei Takeda,
  • Masato Okazaki,
  • Yoshiaki Maruoka and
  • Satoshi Minakata

Beilstein J. Org. Chem. 2015, 11, 9–15, doi:10.3762/bjoc.11.2

Graphical Abstract
  • metal complexes through the coordination at the diazene unit [15][16][17]. Taking 7,8-diaza[5]helicene as an example, conventional methodologies of preparing such compounds (Scheme 2) involve i) reductive coupling of 2-nitronaphthalenes using strong reductants like Zn dust [1][18] and PH3 [19], ii
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Published 05 Jan 2015

Recent advances in the electrochemical construction of heterocycles

  • Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

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  • polymer films. In the context of heterocycle synthesis, a number of mediators based on organic molecules, inorganic salts and metal complexes have been used recently and their use will be discussed later on the basis of the relevant examples. 1 Intramolecular cyclizations 1.1 Anodic olefin coupling The
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Published 03 Dec 2014

A novel 4-aminoantipyrine-Pd(II) complex catalyzes Suzuki–Miyaura cross-coupling reactions of aryl halides

  • Claudia A. Contreras-Celedón,
  • Darío Mendoza-Rayo,
  • José A. Rincón-Medina and
  • Luis Chacón-García

Beilstein J. Org. Chem. 2014, 10, 2821–2826, doi:10.3762/bjoc.10.299

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  • are tolerated. Keywords: 4-aminoantipyrine; arylboronic acids; biaryls; cross-coupling; palladium(II) complex; Introduction The sp2–sp2 carbon–carbon bond formation through cross-coupling reactions catalyzed by metal complexes has emerged as a powerful tool in organic synthesis [1][2][3][4][5][6
  • -free catalysts for SM coupling reactions. Transition metal complexes that have shown a wide range of biological activity are those containing the pyrazolone derivative 4-aminoantipyrine (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one, or simply “4-AAP”) [18]. Pyrazoles, in general, are one of the
  • complexes of 4-AAP have shown anti-inflammatory, analgesic, antiviral, antipyretic, antirheumatic and antimicrobial activity [20][21]. Despite the potential biological importance of 4-AAP, the catalytic activity of its transition metal complexes for C–C bond formation have not yet been investigated. Herein
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Published 01 Dec 2014
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  • ions and CD in aqueous media under respect of color change. Findings The aim of this work was to synthesize the polymerizable azo dye N-(4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide (5) which should potentially be able to form stable azo–metal complexes in aqueous solutions. Therefore
  • -copper complexes in aqueous media. In result we could show that supramolecular structures and metal complexes open up a wide field for the development of novel stimuli-responsive polymer materials. We thus described that the simple addition of copper and γ-CD to a poly((4-hydroxy-3-(pyridin-3-yldiazenyl
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Published 24 Oct 2014

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

  • Matthieu Jouffroy,
  • Rafael Gramage-Doria,
  • David Sémeril,
  • Dominique Armspach,
  • Dominique Matt,
  • Werner Oberhauser and
  • Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

Graphical Abstract
  • nested in the α-CD cavity of 12, and located outside the β-CD cavity in 13. Clearly, size selectivity is at work in these metal complexes. As already observed for complex 4, both 12 and 13 are remarkably stable and can be purified by column chromatography on SiO2. This makes them, a priori, good
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Published 15 Oct 2014

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

  • Jan Szabo,
  • Kerstin Karger,
  • Nicolas Bucher and
  • Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

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  • . Molecular architectures of this kind could be useful under several aspects, for example in biologically active compounds, as novel ligands in metal complexes, for the construction of dendrimers, and in crystal engineering. Along these lines, several 1,2,3-tris(iminyl)guanidines have been prepared from
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Published 24 Sep 2014

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

  • Marijana Radić Stojković,
  • Marko Škugor,
  • Łukasz Dudek,
  • Jarosław Grolik,
  • Julita Eilmes and
  • Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

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  • -stranded oligo dT–rA can be reported and its stability and structure studied in detail by monitoring the changes in ICD shape and intensity. Furthermore, DBTAA–derivatives are azamacrocyclic ligands and thus have additional potential to bind metal cations [24], such metal complexes offering a variety of
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Published 12 Sep 2014

Comparing kinetic profiles between bifunctional and binary type of Zn(salen)-based catalysts for organic carbonate formation

  • Carmen Martín and
  • Arjan W. Kleij

Beilstein J. Org. Chem. 2014, 10, 1817–1825, doi:10.3762/bjoc.10.191

Graphical Abstract
  • stopped, reactors were cooled and depressurized. The conversion of the substrate was examined by 1H NMR spectroscopy (CDCl3) of an aliquot taken from the crude reaction mixture. For a photograph of the Amtec reactor system see Supporting Information File 1. Structures of some metal complexes used as
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Published 08 Aug 2014

Triazol-substituted titanocenes by strain-driven 1,3-dipolar cycloadditions

  • Andreas Gansäuer,
  • Andreas Okkel,
  • Lukas Schwach,
  • Laura Wagner,
  • Anja Selig and
  • Aram Prokop

Beilstein J. Org. Chem. 2014, 10, 1630–1637, doi:10.3762/bjoc.10.169

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  • molecules. Since no metal complexes are required to catalyze the 1,3-dipolar cycloaddition [41][42][43], the reaction can be even used for the functionalization of biomolecules in living systems and has therefore been called bioorthogonal [34][35]. To the best of our knowledge, no examples of the Ti
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Published 17 Jul 2014

Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects

  • Axel G. Griesbeck and
  • Melissa Reckenthäler

Beilstein J. Org. Chem. 2014, 10, 1143–1150, doi:10.3762/bjoc.10.114

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  • visible region and appropriate redox activity in the excited states. Many potent photoredox catalysts with sufficient long-term stability are transition metal complexes with excited MLCT states that can be generated in the visible. Another important group of photocatalytic active compounds are
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Published 19 May 2014

Organic synthesis using photoredox catalysis

  • Axel G. Griesbeck

Beilstein J. Org. Chem. 2014, 10, 1097–1098, doi:10.3762/bjoc.10.107

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  • many cases appropriate sacrificial components. In recent years, three major groups of light-absorbing molecules/materials have been (re)investigated, which facilitate a wide range of redox activation from their excited states: transition metal complexes (e.g., the thoroughly investigated Ru(bipy)3 and
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Published 12 May 2014

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

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  • P-nucleophile or the C-electrophile. Chiral phosphines have attracted more and more interest since they are employed as ligands in transition metal complexes to perform asymmetric catalysis [117]. Enantiopure phosphines have mostly been prepared by starting from enantiopure products or by resolution
  • . The methodologies for catalytic asymmetric hydrophosphination of olefins are limited. Chiral metal complexes have been used to promote and control the asymmetric P–H addition reaction. Recent reviews covering the asymmetric hydrophosphination reaction catalyzed by metal catalysts have been published
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Published 09 May 2014

On the mechanism of photocatalytic reactions with eosin Y

  • Michal Majek,
  • Fabiana Filace and
  • Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

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  • vast majority of photochemical reactions known until the 1980s exploited stoichiometric amounts of a photoactive molecular entity to drive a chemical transformation [1]. Only recently, a steadily growing number of homogeneous transition metal complexes which are redox-active and show absorption in the
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Published 30 Apr 2014

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

  • Jacques Lalevée,
  • Sofia Telitel,
  • Pu Xiao,
  • Marc Lepeltier,
  • Frédéric Dumur,
  • Fabrice Morlet-Savary,
  • Didier Gigmes and
  • Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

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  • . Previously reported PIC (based on metal complexes) [45][46][47][48][49][50][51][52]. Previously reported PIC (metal free organic molecules) [54][55]. Typical oxidation and reduction agents used through the photoredox catalysis approach in polymerization photoinitiating systems. Typical monomers that can be
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Published 15 Apr 2014

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

  • Christopher Kremer,
  • Gregor Schnakenburg and
  • Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

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  • bringing together or separating the cyclodextrin moieties from each other. Keywords: allosteric receptors; 2,2’-bipyridines; β-cyclodextrin; supramolecular chemistry; metal complexes; Introduction In biological systems, recognition events play a major role to guarantee the selectivity of essential
  • on-state in the absence of the effector and changes its conformation to the open off-state upon binding of it. In this article we present the synthesis of three new cyclodextrin-functionalised 2,2’-bipyridines 1–3 differing in the bipyridine’s substitution pattern (Scheme 2) and their metal complexes
  • metal complexes’ host–guest chemistry at a later stage in a quantitative manner, however, a 1:2 metal-to-ligand stoichiometry like in the [Zn(1)2]-complexes is not very easy to study because one has to deal with a very complicated equilibrium between 1:2:2, 1:2:1, 1:2:0 and even more complicated metal
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Published 09 Apr 2014

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

  • Alexander F. Khlebnikov,
  • Mikhail S. Novikov,
  • Viktoriia V. Pakalnis,
  • Roman O. Iakovenko and
  • Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

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  • into pyrazines, even when stored in a fridge. Different mechanisms of dimerization were assumed, such as formation and dimerization of nitrile ylides [37][40], hydrolysis to α-aminoketenes followed by condensation [37][41], intermediate formation of metal complexes in the reaction mediated by metals
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Published 04 Apr 2014

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

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  • . Keywords: concave templates; metal complexes; self-assembly; self-sorting; 9,9’-spirobifluorene; supramolecular chemistry; Introduction Concave templates are versatile tools to achieve self-sorting behaviour in the self-assembly of defined aggregates from multicomponent mixtures in a social self
  • (C-9), 24.8 (C-17) ppm (* signal assignment might be interchanged); HRMS-ESI (m/z): [M + H]+ calcd for [C37H27N2]+, 499.2169; found, 499.2160. [α]D24 −128.1° (c 0.39, CHCl3). Preparation and characterisation of the metal complexes: Approximately 10 µmol of a ligand and an equimolar amount of [(dppp
  • metal complexes. Acknowledgements Financial support from the DFG (SFB 624) and the Academy of Finland (KR. grant no. 265328 and 263256) and the NGS-NANO (FT) is gratefully acknowledged.
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Published 18 Feb 2014

Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings

  • Shinichiro Fuse,
  • Nobutake Tanabe,
  • Akio Tannna,
  • Yohei Konishi and
  • Takashi Takahashi

Beilstein J. Org. Chem. 2013, 9, 2336–2343, doi:10.3762/bjoc.9.268

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  • Co complex (Figure 1) [22]. Stephan and coworkers reported the synthesis of a bulkier chelating ligand 2a, and its use in the formation of various metal complexes [20][21]. Rojas and coworkers reported the synthesis of a series of bulky chelating ligands 2b–g, and detailed their use in the
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Published 01 Nov 2013

Gold(I)-catalyzed enantioselective cycloaddition reactions

  • Fernando López and
  • José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

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  • , cycloadditions are atom economical, and usually take place with high levels of regio- and stereocontrol. Especially relevant in terms of synthetic practicality are cycloadditions which are catalyzed by transition metal complexes [19][20][21][22][23]. In particular, gold(I) complexes, owing to their high
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Published 30 Oct 2013
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