Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

• Martin Popr,
• Sergey K. Filippov,
• Nikolai Matushkin,
• Juraj Dian and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20

• drug formulation such as “smart” plasters or bandages capable of prolonged release of the antiseptic drug. There are several examples of deposition of CD derivatives onto a solid support in the literature. The most common immobilization method is binding of various alkylthio-CDs onto a gold surface [16

• ][17][18]. This approach offers self-assembled monolayers (SAMs) which can be utilized for derivatization of gold electrodes for the construction of electrochemical sensors [19][20] or even for the development of molecular printboards [21]. These results imply that the structure of CD derivatives

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• derivatives are one of the most intensively studied families of biologically active compounds with efficient DNA binding capability. Attracting attention since DNA structure discovery (1960s), they were early recognized as a symbol of DNA intercalative binding, for many decades applied as gold-standard DNA

• of some phenanthridinium compounds became apparent [1]. One of the most studied and used phenanthridine derivatives is 3,8-diamino-5-ethyl-6-phenylphenanthridinium known as ethidium bromide (EB), for many decades applied as gold-standard DNA- and RNA-fluorescent marker, and its close analogue

• phenanthridine (Scheme 20) [44]. The synthesis by multicomponent tandem reaction/carbocyclization starts with the formation of a 4-aryl-3-arylethynylisoquinoline from 2-bromobenzaldehyde/tert-butylamine/1,3-diyne. The second (in situ) step is based on the ring closure, either via gold/silver-catalysed

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• (SAMs) are increasingly being used as a means of surface modification to alter properties in a tuneable manner [1][2][3]. The major classes of SAMs are those with adsorbed long chain alkyl thiols on gold surfaces/nanoparticles [4][5], or long chain alkylsilanes on silica surfaces [6][7]. Two general

Improving ITC studies of cyclodextrin inclusion compounds by global analysis of conventional and non-conventional experiments

• Eléonore Bertaut and
• David Landy

Beilstein J. Org. Chem. 2014, 10, 2630–2641, doi:10.3762/bjoc.10.275

• and release experiments. In terms of accuracy, it seems that the titration-release approach should be considered as the gold standard. However, in terms of reliability, implementation of each non-conventional experiment for a given complex may provide additional information on the adequacy between

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• , involving gold(I)-catalysed cyclisation of an alkynyl alcohol to form the furan ring. The furan analogue of thiamine diphosphate (ThDP) was also made and tested for binding to and inhibition of pyruvate decarboxylase (PDC) from Zymomonas mobilis (overexpressed in E. coli with a N-terminal His-tag). It is a

• very strong inhibitor, with a Ki value of 32.5 pM. It was also shown that the furan analogue of thiamine can be functionalised at the C-2 position, which will allow access to mimics of reaction intermediates of various ThDP-dependent enzymes. Keywords: furan synthesis; gold-catalysed cyclisation

• planned synthesis was the formation of the furan ring. Homogeneous gold-catalysed reactions have been used recently in the synthesis of furans from alkynes [13][14][15][16][17][18][19][20]. The ease with which alkynes, allenes and alkenes can be activated by Au(I) catalysts to form carbon–carbon and

Theoretical study of the adsorption of benzene on coinage metals

• Werner Reckien,
• Melanie Eggers and
• Thomas Bredow

Beilstein J. Org. Chem. 2014, 10, 1775–1784, doi:10.3762/bjoc.10.185

• = Cu), silver (M = Ag) and gold (M = Au) is studied on the basis of density functional theory (DFT) calculations with an empirical dispersion correction (D3). Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE) in combination with different versions of the dispersion correction

• crucial role for the adsorption of large aromatic compounds on metal surfaces [9][10][11]. This holds in particular for the adsorption on the coinage metals copper, silver and gold. Therefore, a theoretical treatment of this process requires methods that provide an accurate description of these weak

• dependent C6 coefficients of the D3 correction. We checked this by calculating the C3 coefficients for the benzene adsorption on the Au(111) surface. Previous theoretical studies of the adsorption of organic compounds on silver and gold surfaces resulted in a good agreement with experimental results [9][10

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• our group [24][25]. When they are coupled by amide bonds to gold nanoparticle and O-sulfated these conjugates gave extremely high binding affinities towards L- and P-selectin in sub-nanomolar concentrations. These results were achieved by a multivalent presentation (ca. 1000–1200 ligands per

Improving the reactivity of phenylacetylene macrocycles toward topochemical polymerization by side chains modification

• Simon Rondeau-Gagné,
• Jules Roméo Néabo,
• Maxime Daigle,
• Katy Cantin and
• Jean-François Morin

Beilstein J. Org. Chem. 2014, 10, 1613–1619, doi:10.3762/bjoc.10.167

• present any gelation properties. For SEM analysis, a gel sample was allowed to dry at room temperature on a metallic substrate to form a xerogel. Then, gold was sputtered on the sample prior to imaging. SEM images of PAM2 are shown in Figure 2. As previously observed with PAM1 and other phenylacetylene

C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog

• Sebastian Rabe,
• Johann Moschner,
• Marina Bantzi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 1564–1569, doi:10.3762/bjoc.10.161

• was thought to establish the C-nor-D-homo steroid system, and a gold-catalyzed amination/annulation/aromatization sequence was planned to install the pyridine F-ring. Diazo compound 3 originates from diene 4 through standard transformations, the latter being accessible from commercially available and

• product 13 by chromatography was then achieved after selective hydrogenation of only the exocyclic olefin in 14 (H2, cat. Rh/C, EtOAc, 25 °C, structure of hydrogenation product not shown) employing the mixture of the isomers 13 and 14 from the previous step. Finally, a gold-catalyzed amination/annulation

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones

• Jubi John,
• Eliza Târcoveanu,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150

• towards 4-substituted-furanones from imines [41]. Recently Fructos et al. have shown that N-p-toluenesulfonyl-protected imines were better candidates for gold catalyzed Mannich addition of acetoacetates when compared to N-Boc (tert-butoxycarbonyl) and N-PMP (p-methoxyphenyl) imines [42]. Hence, we

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• -caprolactone for targeting dendritic cells and macrophages (Figure 4) [45] Both mannose and galactose were attached to PEGylated nanoparticles by click-chemistry between their propargyl glycosides and a gold nanoparticles derivatized with an azide-functionalized PEG [46]. Also, several unprotected carbohydrate

Glycosystems in nanotechnology: Gold glyconanoparticles as carrier for anti-HIV prodrugs

• Fabrizio Chiodo,
• Marco Marradi,
• Javier Calvo,
• Eloisa Yuste and
• Soledad Penadés

Beilstein J. Org. Chem. 2014, 10, 1339–1346, doi:10.3762/bjoc.10.136

• to improve HIV drug treatment and prevention. In this scenario, gold nanoparticles are an interesting chemical tool to design and prepare smart and efficient drug-delivery systems. Here we describe the preparation and antiviral activity of carbohydrate-coated gold nanoparticles loaded with anti-HIV

• prodrug candidates. The nucleoside reverse transcriptase inhibitors abacavir and lamivudine have been converted to the corresponding thiol-ending ester derivatives and then conjugated to ~3 nm glucose-coated gold nanoparticles by means of “thiol-for-thiol” ligand place exchange reactions. The drugs

• -containing glyconanoparticles were characterized and the pH-mediated release of the drug from the nanoparticle has been determined. The antiviral activity was tested by evaluating the replication of NL4-3 HIV in TZM-bl infected cells. The proof-of-principle presented in this work aims to introduce gold

Synthesis, characterization and DNA interaction studies of new triptycene derivatives

• Sourav Chakraborty,
• Snehasish Mondal,
• Rina Kumari,
• Sourav Bhowmick,
• Prolay Das and
• Neeladri Das

Beilstein J. Org. Chem. 2014, 10, 1290–1298, doi:10.3762/bjoc.10.130

• per the manufacturer’s yield report. Calf thymus DNA (ctDNA), ethidium bromide (EtBr), chemicals for buffer preparation and synthesis were purchased from Sigma-Aldrich or Alfa Aesar and were used as received. Sybr-Gold® nucleic acid stain was obtained from Invitrogen. Gel images were captured by

• DNA samples were further incubated with 5 units of APE1 enzyme for 1 hour at 37 °C and analyzed by 25% denaturing PAGE run in tris-taurine-EDTA (TTE) buffer at pH 8.0, stained with Sybr-Gold®, gel images acquired and quantified. Fluorescence and absorption spectroscopy The ethidium bromide (EtBr

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

• catalysis (Table 16) [244]. Besides copper(I) iodide several other copper salts effectuated the reaction albeit in lower yields as did silver(I) iodide, palladium(II) chloride and platinum(II) chloride. Other transition metal catalysts such as gold(I) chloride, nickel(II) chloride and cobalt(II) chloride

Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

• Anna Kovářová,
• Svatopluk Světlík,
• Václav Kozmík,
• Jiří Svoboda,
• Vladimíra Novotná,
• Damian Pociecha,
• Ewa Gorecka and
• Natalia Podoliak

Beilstein J. Org. Chem. 2014, 10, 794–807, doi:10.3762/bjoc.10.75

• book-shelf (planar) geometry. For dielectric spectroscopy 12 μm cells with gold electrodes were used. Dielectric properties were studied using a Schlumberger 1260 impedance analyser. The frequency dispersions were measured on cooling at a rate of about 0.2 K/min, keeping the temperature of the sample

• resistance of the electrodes, respectively. Due to the gold electrodes the contribution of a parasitic term was negligible up to 2 MHz. Measured values of real, ε′, and imaginary, ε′′, part of the complex permittivity were simultaneously fitted to Equation 1. Switching properties were studied with driving

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• . 2,5-dihalogenated furans can be in principle employed in cross-coupling reactions, however, the poor stability of these dihalogenated precursors renders this approach very tedious [29]. Recent publications report gold-catalyzed syntheses of di(hetero)arylfurans starting from arylbutadiynes [30][31

• ]. However, the major drawback of this approach is the complex, time-consuming preparation of the complicated gold catalyst and the separate synthesis of the butadiyne substrates. In a similar study arylbutadiynes prepared by Glaser homocoupling were converted into symmetrical 2,5-di(hetero)arylfurans [32

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• Giorgio Abbiati Elisabetta Rossi Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Generale e Organica “A. Marchesini”, Università degli Studi di Milano, Via Venezian, 21 – 20133 Milano, Italy 10.3762/bjoc.10.46 Abstract Silver and gold salts and complexes mainly act as soft and

• carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I)/Au(III)-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their application in

• multicomponent reactions. Keywords: A3-coupling; gold; multicomponent reactions; silver; Introduction Coinage metals (copper, silver and gold) are extensively used in the homogenous catalysis of organic reactions. Similarities and differences in the catalytic activity of these elements have been recently

Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

• Antonio Arcadi,
• Emanuela Pietropaolo,
• Antonello Alvino and
• Véronique Michelet

Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42

• Paris, UMR 8247, Ecole Nationale Supérieure de Chimie de Paris, Chimie ParisTech, 11 rue P. et M. Curie, F-75231 Paris Cedex 05, France 10.3762/bjoc.10.42 Abstract The scope and limitations of gold-catalyzed tandem cycloisomerization/fluorination reactions of unprotected 2-alkynylanilines to have

• access to 3,3-difluoro-2-aryl-3H-indoles and 3-fluoro-2-arylindoles are described. An unprecedented aminoauration/oxidation/fluorination cascade reaction of 2-alkynylanilines bearing a linear alkyl group on the terminal triple bond is reported. Keywords: 2-alkynylanilines; fluorination; gold catalysis

• and alkynyl phenylhydrazones, respectively. Propargyl amidines were converted into 5-fluoromethylimidazoles in the presence of Selectfluor under gold(I) catalysis [34][35][36] through a cascade cyclization/fluorination process [37]. Following our previous work on gold catalysts (Scheme 1) [38], we

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• stereocontrol and the flexibility concerning the chain length. In 2005, Al-Harrasi synthesized the first tert-butyldimethylsilyl (TBS)-protected aminopyrans (n = 0) and aminooxepanes (n = 1) via this reaction route [23]. Several of the poly(hydroxy)aminopyrans [24] were connected to gold nanoparticles and the

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

• schisanwilsonene A (126, see Scheme 15), isolated from Schisandra wilsoniana [111], a plant used in traditional chinese medicine. Submission of 1,6-enyne 116 to cationic gold-catalyst 117 led to 5-exo-dig cyclization and intermediate formation of bridged bicycle 119. Subsequent 1,5-acyl-shift afforded

• as the corresponding bis-zinc-enolate species. DVCPR occurred at ambient temperature, final acidic workup provided cycloheptadione 247 in excellent yield (see Scheme 31). Toste and coworkers [203] reported a tandem gold-catalyzed Claisen rearrangement from popargyl vinyl ether 248 (see Scheme 32) to

• . Toste and coworkers [205] discovered a 1,2-pivaloyl shift and cyclopropanation of the resulting gold-carbenoid from 258 with enyne 259 to yield vinylalkynecyclopropane 260. This compound was shown to undergo a gold catalyzed DVCPR to yield 261. Note that this reaction does most likely proceed via a step

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• micrographs are prepared by cutting a piece of gel and putting it on the surface of a glass plate to dry at room temperature. Samples for SEM are prepared by flash freezing in liquid nitrogen followed by lyophilisation, and the freeze-dried sample was placed on a silica surface to be coated by gold before the

The renaissance of organic radical chemistry – deja vu all over again

• Corey R. J. Stephenson,
• Armido Studer and
• Dennis P. Curran

Beilstein J. Org. Chem. 2013, 9, 2778–2780, doi:10.3762/bjoc.9.312

• homolytic aromatic substitution (BHAS) [3], b) photoredox catalysis [4][5][6][7][8], c) redox chemistry using Bu4NI in combination with t-BuOOH [9], d) transition metal catalyzed processes where radicals are suggested to interact directly with copper, nickel, zinc, palladium, gold and so on [10][11][12][13

One-pot cross-enyne metathesis (CEYM)–Diels–Alder reaction of gem-difluoropropargylic alkynes

• Santos Fustero,
• Paula Bello,
• Javier Miró,
• María Sánchez-Roselló,
• Günter Haufe and
• Carlos del Pozo

Beilstein J. Org. Chem. 2013, 9, 2688–2695, doi:10.3762/bjoc.9.305

• reactions for the preparation of different difluoropropargylamides and ketones, having been subjected to intramolecular hydroaminations [23], cascade RCEYM–Diels–Alder reactions [24], [2 + 2 + 2] cycloadditions and gold-mediated dimerization reactions [25]. Although the CEYM reaction has been found to be

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

• Mathieu Morin,
• Patrick Levesque and
• Louis Barriault

Beilstein J. Org. Chem. 2013, 9, 2625–2628, doi:10.3762/bjoc.9.297

• Mathieu Morin Patrick Levesque Louis Barriault Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Canada K1T 1B5 10.3762/bjoc.9.297 Abstract Gold(I) complexes have emerged as powerful and useful catalysts for the formation of new C–C, C–O and C–N

• ; cyclization; gold(I); gold catalysis; heterocycles; regioselectivity; Introduction In the last decade, phosphino and NHC–gold complexes have become prominent catalysts for the addition of nucleophiles to alkenes, alkynes and allenes [1][2][3][4][5][6][7][8][9][10][11]. Owing to the high affinity of gold(I

• ) complexes to C–C π-systems in the presence of other functional groups combined by its predictable reactivity pattern, the gold(I)-catalyzed reaction provides tremendous opportunities for the discovery of new and useful reactions [12]. Recently, we [13] and other groups [14][15][16][17] reported that

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• intends to summarize the recent progresses in the field, with particular emphasis on mechanistic details. Keywords: alkene; gold catalysis; mechanism; organic synthesis; Review 1 Introduction Homogeneous gold catalysis is emerged as one of the most powerful means for the activation of C–C multiple bonds

• toward a number of complexity-oriented transformations. In this segment, gold-catalyzed addition of carbon- and heteroatom-based nucleophiles to inactivated alkenes are widely recognized as “capricious” transformations due to alkyne and allene counterparts [1][2][3][4][5]. However, over the past few

• years, tremendous developments were made, and some of the major contributes will be summarized in the present review. Mechanistically, it is generally accepted that the gold-catalyzed nucleophilic addition to alkenes proceeds through three elementary steps: i) activation of the C–C double bond by gold