Synthetic mRNA capping

• Fabian Muttach,
• Nils Muthmann and
• Andrea Rentmeister

Beilstein J. Org. Chem. 2017, 13, 2819–2832, doi:10.3762/bjoc.13.274

• [71]. Furthermore, cap analogues providing additional functions were synthesized. A photo-crosslinking cap analogue containing a 6-thioguanosine was prepared which allowed for selective crosslinking [72]. Successful crosslinking was exemplified by the intrastrand crosslinking of histone H4 mRNA capped

• tetrazoles. Even photo-crosslinking moieties were enzymatically transferred to the N7-position of the mRNA cap from suitable AdoMet analogues. Notably, quantitative modification at the N7-position was achieved [96]. Diazirine and aryl–azide photo-crosslinker moieties were functional showing cross-linking to

• for additional bioconjugation reactions. A combination of chemical 5′-cap analogue synthesis followed by enzymatic modifications has further allowed conferring novel functionalities (e.g., photo-crosslinking moieties) which were previously not easily accessible. Combining enzymatic modification at

Biomimetic molecular design tools that learn, evolve, and adapt

• David A Winkler

Beilstein J. Org. Chem. 2017, 13, 1288–1302, doi:10.3762/bjoc.13.125

• applied to modelling materials other than small, discrete, organic molecules, with considerable success. Many types of materials are considerably more complex than small organic molecules (e.g., with size and weight distributions, diverse shapes, variable degree of crosslinking, different degrees of

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• and purify proteins by covalent crosslinking (Figure 5). GAuNPs were synthesized by coating the metal surface via thio-chemistry with a β-D-lactose residue (recognized by a series of lectins, i.e., PNA or Ricinus communis agglutinin) and a benzophenone moiety as photoreactive group. GAuNPs were

Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

• modification or addition of a functional group [13]. Controlled degradation – degradation and crosslinking of polymers to produce a product with controlled molecular weight distribution. This results in a higher number of active sites that can later be used for grafting [13]. Reactive blending – this involves

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• technologies (e.g., in situ/ex situ microbial degradation and chemical oxidation of contaminants in soil) [9][10]. Immobilizing CDs either by crosslinking or by coupling to the surface of natural or synthetic polymers CD-based sorbents are obtained in the form of beads, nanosponges, microfibers, etc., which

• -M/P) and quaternary ammonium β-cyclodextrin polymer (QABCD-P) in a concentration of 1% (50 mg/5 mL). The polymers were prepared by crosslinking the proper monomers with epichlorohydrin and contained 4–200 β-CD units. None of the monomers could hinder the aggregation of nanoTiO2 in 0.1% NaCl solution

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• , which is generated by the actions of cytochrome P450 (Oxy) enzymes that affect the crosslinking of aromatic side chains of amino acid residues contained within the GPA heptapeptide precursor. Given the crucial role peptide cyclisation plays in GPA activity, the characterisation of this process is of

• products and are highly effective antibiotics against Gram-positive bacteria, where they affect their function by preventing the correct crosslinking of the peptidoglycan cell wall [1]. Produced by bacteria, these compounds derive their efficacy from their unique three-dimensional structure, which in turn

• enables them to bind to the dipeptide terminus of the peptidoglycan precursor lipid II [1][2]. This three-dimensional structure is generated by the high degree of crosslinking exhibited by the glycopeptide antibiotics: in the case of the two most widely known natural examples (vancomycin and teicoplanin

Synthesis of three-dimensional porous hyper-crosslinked polymers via thiol–yne reaction

• Mathias Lang,
• Alexandra Schade and
• Stefan Bräse

Beilstein J. Org. Chem. 2016, 12, 2570–2576, doi:10.3762/bjoc.12.252

• metal-free reaction conditions, high yields and easy purification. Results and Discussion The first network shown here was synthesized by crosslinking the two tetrahedral tetraphenylmethane core structures 1 and 2 via the radical-mediated thiol–yne reaction using AIBN as initiator. The second network

• thiols, respectively. However, these characteristic bands are nearly extinguished in the IR spectra of the HCPs showing a high ratio of crosslinking for these reactions. In addition, the vibration bands of the HCPs at 3000 cm−1 correspond to the presence of olefinic bonds, which is in accordance to a

• crosslinking reaction conditions. The obtained HCPs showed BET surface areas up to 650 m²/g and are insoluble in common organic solvents. The characterisation of the networks was performed using IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), powder X

Methylenelactide: vinyl polymerization and spatial reactivity effects

• Judita Britner and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232

• polymers were obtained, the C–H bonds in the linear MLA-polymer units must be more stable than in the monomeric MLA. Otherwise, crosslinking should take place via spontaneous C–H cleavage and chain recombination. This important point could be verified by IR spectroscopy and also by theoretical calculations

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• Abstract In this study, a polymer, prepared by crosslinking cyclodextrin (CD) by means of a polycarboxylic acid, was used for the removal of pollutants from spiked solutions and discharge waters from the surface treatment industry. In spiked solutions containing five metals, sixteen polycyclic aromatic

• . As expected, the signals of the BTCA crosslinking agent can be clearly distinguished (labeled a, b, c and d). In particular, the carbon of the carboxylic groups appears at 172.2 ppm. This peak (a,d) corresponds to esterified and free carboxylic groups of BTCA present in free carboxylic acids and in

• The cross-linked polymer (Figure 1) was prepared in a single step by crosslinking hydroxypropyl-β-cyclodextrin (HPβCD; Kleptose HPB®, DS = 0.62, Roquette, Lestrem, France) using 1,2,3,4-butanetetracarboxylic acid (BTCA; Aldrich, Milwaukee, WI). The synthesis procedure has already been described in

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• present the synthesis of paraffin-like oligomers via double alkylation of N-VP with 1,8-dibromooctane. Additionally, this work focuses on the use of the free double bonds for radical crosslinking as well as thiol-ene modification for subsequent dye attachment. Results and Discussion N-Vinylpyrrolidone (1

Superstructures with cyclodextrins: chemistry and applications III

• Gerhard Wenz and
• Eric Monflier

Beilstein J. Org. Chem. 2016, 12, 937–938, doi:10.3762/bjoc.12.91

• styrene from ethylbenzene [3][4]. Highly porous networks were synthesized by crosslinking β-CD with tetrafluoroterephthalonitrile. These networks were able to almost completely remove pollutants (e.g., bisphenol A) within a short time from wastewater [5]. Stimuli-responsive nanoparticles were assembled by

• has been achieved in the synthesis of CD polyrotaxanes. The one-pot and one-step polyrotaxane synthesis of β-CDs was performed in aqueous solution by employing a click reaction [7] as well as by radical copolymerization [8]. Slide-ring gels, synthesized by the group of K. Ito through the crosslinking

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• , while nanostructure size and shape were regulated according to the structure of the CD-PG dendrons [75]. CD-based polymers can be easily prepared under MW. Biswas et al. have prepared a number of macromolecular structures from α-, β-, γ-CDs by crosslinking reactions with toluene diisocyanate and

Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time ¹³C CP-MAS solid-state NMR characterization

• Isabelle Mallard,
• Davy Baudelet,
• Franca Castiglione,
• Monica Ferro,
• Walter Panzeri,
• Enzio Ragg and
• Andrea Mele

Beilstein J. Org. Chem. 2015, 11, 2785–2794, doi:10.3762/bjoc.11.299

• aliphatic CH2 at 2900 cm−1 and the OH stretching vibration between 3700 and 3000 cm−1. As a consequence of the crosslinking process with EP, the spectra of D1, D2 and D3 exhibited a new stretching vibration assigned to CH2 groups at 2970 cm−1, and a scissoring bending vibration at 1400 cm−1. The presence of

Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

• Shintaro Kawano,
• Toshiyuki Kida,
• Mitsuru Akashi,
• Hirofumi Sato,
• Motohiro Shizuma and
• Daisuke Ono

Beilstein J. Org. Chem. 2015, 11, 2355–2364, doi:10.3762/bjoc.11.257

• -active property. Results: CD nanogels were prepared by crosslinking heptakis(2,6-di-O-methyl)-β-cyclodextrin with phenyl diisocyanate and subsequent immersion of the resulting polymer in water. A dynamic light scattering study shows that primary CD nanogels with 30–50 nm diameter assemble into larger CD

• DM-β-CD polymers bearing a [MDI or PDI]/[DM-β-CD] feed ratio of more than three has a lipophilic nature, they show a poor hydrophilicity. Controlling the degree of crosslinking should provide an appropriate balance between the hydrophilicity and hydrophobicity, generating an amphiphilic crosslinked

• polymers in water. Results and Discussion Preparation and characterization of the CD nanogels Nanometer-sized CD nanogels were prepared by crosslinking DM-β-CD with PDI and subsequent immersion of the resulting polymers in water (Figure 1). The crosslinking reaction was performed at 70 °C for 24 h (the

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• . Although TES-PR can be isolated just by vacuum drying to evaporate the reactant and solvent, the solid isolated in this way becomes insoluble in any solvent. This is due to the crosslinking induced by reactions between CDs. Thus, DMSO was added to the reaction solution first, followed by drying the

• rubbers, the theory is already invalid due to the presence of strong interactions between polymers and embedded particles in addition to the covalent crosslinking points. However, such interactions increase not, decrease, modulus. Thus, the interactions between the polyrotaxane and silica cannot explain

• content. Synthesis of polyrotaxane with partially triethoxysilylated α-CDs (TES-PR) and crosslinking of the polyrotaxane solution via the reaction between the CDs and the surface of silica nanoparticles. Acknowledgements This work was partially funded by JSPS KAKENHI Grant Number 25220603 and ImPACT

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• project, the presence or the degree of crosslinking in the material has not been determined. The results of the emulsion ROMP experiments are summarized in Table 4. Evidently, NHC-ligated catalysts 11 and 12 exhibit a much elevated activity under microemulsion conditions in comparison to their water

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• second step for polymerisation or crosslinking without the lipase. By exploiting the substrate selectivity of lipases it is possible to obtain well-defined telechelics in a one-pot, or even one-step reaction. In 1997 Uyama et al. were the first to produce telechelic polyesters from the monomers divinyl

• approach the same research group synthesized the telechelic tetraallyl ether-poly(butylene adipate) (Figure 22). Each telechelic molecule carried four allyl ether groups, which allowed extensive crosslinking using thiolene chemistry with dithiols or tetrathiols [79]. Through a combination of lipase

• after filtering off the enzyme. The properties of the films depended on the fraction of pentadecalactone and crosslinking density [80]. Conclusion In this short review it has been discussed the synthetic potential of dicarboxylic esters in biocatalyzed reactions. Literature examples related to

Peptide–polymer ligands for a tandem WW-domain, an adaptive multivalent protein–protein interaction: lessons on the thermodynamic fitness of flexible ligands

• Katharina Koschek,
• Vedat Durmaz,
• Oxana Krylova,
• Marek Wieczorek,
• Shilpi Gupta,
• Martin Richter,
• Alexander Bujotzek,
• Christina Fischer,
• Rainer Haag,
• Christian Freund,
• Marcus Weber and
• Jörg Rademann

Beilstein J. Org. Chem. 2015, 11, 837–847, doi:10.3762/bjoc.11.93

• superior to induce multivalent binding and to increase affinity, while the more flexible and dendritic polymers, pHPMA and hPG are suitable to induce crosslinking upon binding. Keywords: inhibitors of protein–protein interactions; isothermal titration calorimetry; multivalency; peptide–polymer conjugates

• multivalency of binding and/or the degree of crosslinking. Thus, the method enables the identification of polymer–protein aggregates containing several polymers and proteins in a complex. No precipitation of the multicomponent aggregates that interfered with ITC measurements was observed during the experiments

• formed peptide-polymer–protein complex. Inspection of the test solution revealed the formation of a colloidal suspension/dispersion both for pHPMA and for hPG-based peptide conjugates indicating the formation of insoluble aggregates possibly generated through crosslinking. Corresponding to the observed

Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

• Stefanie Krysiak,
• Qiang Wei,
• Klaus Rischka,
• Andreas Hartwig,
• Rainer Haag and
• Thorsten Hugel

Beilstein J. Org. Chem. 2015, 11, 828–836, doi:10.3762/bjoc.11.92

• reduced state [5][9]. The byssal plaque also shows strong cohesion through crosslinks. The cysteins can crosslink with DOPA and the oxidized DOPA (semiquinones) can crosslink via radical addition. Furthermore, crosslinking by iron chelate complexes of DOPA improves cohesion [10]. The adhesion of a single

• hyperbranched polyglycerol as a hydrophilic core with numerous DOPA (catechol) groups attached. A similar system has already proven to be advantageous for an antifouling coating on titanium oxide surfaces [21][22]. An added benefit of this system is that the oxidation of catechol to quinones makes crosslinking

Functionalized branched EDOT-terthiophene copolymer films by electropolymerization and post-polymerization “click”-reactions

• Miriam Goll,
• Adrian Ruff,
• Erna Muks,
• Felix Goerigk,
• Beatrice Omiecienski,
• Ines Ruff,
• Rafael C. González-Cano,
• Juan T. Lopez Navarrete,
• M. Carmen Ruiz Delgado and
• Sabine Ludwigs

Beilstein J. Org. Chem. 2015, 11, 335–347, doi:10.3762/bjoc.11.39

• the electropolymerization can be regarded as a crosslinking step [17][18]. Electropolymerization of monomer mixtures is another powerful tool to modify material properties. Among a variety of monomer mixtures including pyrrole and thiophene [19][20], 2,2’-bithiophene and pyrrole [21][22] and

Anomalous diffusion of Ibuprofen in cyclodextrin nanosponge hydrogels: an HRMAS NMR study

• Monica Ferro,
• Franca Castiglione,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2014, 10, 2715–2723, doi:10.3762/bjoc.10.286

• prepared with a large excess of crosslinking agent. A simple scheme of these processes is shown in Figure 5. The ionization state of the COOH groups is thus expected to play a key role in determining the possibility of a negative electrostatic potential in part of the polymeric backbone, in turn a possible

Synthesis of a resin monomer-soluble polyrotaxane crosslinker containing cleavable end groups

• Ji-Hun Seo,
• Shino Nakagawa,
• Koichiro Hirata and
• Nobuhiko Yui

Beilstein J. Org. Chem. 2014, 10, 2623–2629, doi:10.3762/bjoc.10.274

• with minimal chemical reaction, methacrylate-functionalized PRX with degradable end-capping groups is anticipated to be a useful molecular platform for the development of degradable crosslinking agents. In this study, resin monomer-soluble, methacrylate-functionalized PRX with degradable end-capping

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• organometallic reactions [1] to emulsion polymerization [2][3][4]. By reacting CDs with suitable crosslinking agents, nanostructured hyper-cross-linked materials, known as nanosponges, can be obtained [5][6][7]. Currently there is a growing interest in the synthesis of soluble β-CD-based polymers, which is a

Investigations of thiol-modified phenol derivatives for the use in thiol–ene photopolymerizations

• Sebastian Reinelt,
• Monir Tabatabai,
• Urs Karl Fischer,
• Norbert Moszner,
• Andreas Utterodt and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1733–1740, doi:10.3762/bjoc.10.180

• flexural strength and modulus of elasticity is twice as high compared to the PETMP reference system. Keywords: composites; crosslinking; dental polymers; high performance polymers; photopolymerization; Introduction Restorative composites consist of a polymerizable organic matrix (10–60 wt %) and

Photoswitchable precision glycooligomers and their lectin binding

• Daniela Ponader,
• Sinaida Igde,
• Marko Wehle,
• Katharina Märker,
• Mark Santer,
• David Bléger and
• Laura Hartmann

Beilstein J. Org. Chem. 2014, 10, 1603–1612, doi:10.3762/bjoc.10.166

• the glycooligomer ligands as well. Further studies will evaluate in more detail different potential binding modes such as chelate binding, intermolecular crosslinking, and rebinding effects. In order to approach practical applications of a photoswitchable device that could modulate its binding