A facile synthetic route to benzimidazolium salts bearing bulky aromatic N-substituents

• Gabriele Grieco,
• Olivier Blacque and
• Heinz Berke

Beilstein J. Org. Chem. 2015, 11, 1656–1666, doi:10.3762/bjoc.11.182

• can be tuned and, based on these properties, they possess great electronic flexibility. These ligands or catalysts reached a prominent position in the mentioned fields of chemistry. It is noteworthy that on the material’s side NHC-type carbene–borane adducts and metal complexes of them can also be

• ] salts for two reasons: we wished to find a faster way to access them and it seemed advantageous to aim preferentially at the synthesis of benzimidazolium chlorides than at [BF4]− salts, since in case the carbene will be generated in “in situ” reactions in the presence of metal complexes, the lower

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• , uncommon reaction sequences. Homogeneous PRCs form one class that encompasses soluble organic dyes [1] as well as transition metal complexes; particularly those of Ru and Ir. Study of the latter markedly escalated from 2008 thanks to papers from the groups of MacMillan [2], Yoon [3] and Stephenson [4]. The

Ruthenium indenylidene “1^st generation” olefin metathesis catalysts containing triisopropyl phosphite

• Stefano Guidone,
• Fady Nahra,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2015, 11, 1520–1527, doi:10.3762/bjoc.11.166

• shorten or provide alternative synthetic pathways for the synthesis of natural products displaying complex chemical structures [5][6][7][8][9]. Ru-based pre-catalysts are known to be more air-, moisture- and functional-group tolerant compared to early transition metal complexes [10][11][12][13]. In

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• devoted to the association of a binding or coordinating unit to the redox-active TTF moiety. This strategy has led for example, in solid state, to the preparation of electroactive metal complexes that combine magnetic and electrical properties [12][13][14][15][16][17]. In solution, TTF-based redox

• spectrum observed for other anions. Synthesis and crystal structure of a neutral rhenium complex Few metal complexes based on ruthenium cations have been previously prepared with dinitrophenylazine type ligands [48][49]. These reports indicate that the pyridinedinitrophenylazine type ligands are good

• candidates for the formation of metal complexes. We have therefore investigated the complexation of L1 and L2 with various metal cations and we succeeded in the crystallization of a neutral rhenium metal complex with ligand L2. Thus, the equimolar reaction between L2 and the [Re(CO)5Cl] precursor performed

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• , and carcinogenic [15][16]. That’s why many unconventional methods and techniques have been investigated and a number of studies have been developed [17][18][19]. In particular, attention has been focused on the synthesis of supports having metal complexes in their structures due to their capacities

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• ]. Although devices with the most commonly used dyes based on polypyridyl transition-metal complexes show excellent photovoltaic performances with high power conversion efficiencies of over 11% [4], metal-free organic dyes have significant advantages in several aspects. These comprise for example large molar

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

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

• 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

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

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

• 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

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

• 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

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• 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

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

• 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

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

• . 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

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

• -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

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

• 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

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

• 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

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

• 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

Organic synthesis using photoredox catalysis

• Axel G. Griesbeck

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

• 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

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

• 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