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

• Celoria, 2 I-20133 Milano, Italy 10.3762/bjoc.11.299 Abstract The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were

• epichlorohydrin [15][16], isocyanates [17][18], polycarboxylic acids [19][20] and anhydrides [21]. Following a slightly different approach, Trotta [18] and his group demonstrated that polymerization of cyclodextrins with a variety of synthetic equivalents of di- and tetracarboxylic acids provides an easy

• in shape, size and chemical functionality is achieved due to the presence of the target molecule during the polymerization process (Scheme 1). Initially the target molecules form a complex with the cyclodextrin followed by a copolymerization of the imprinted monomers with the crosslinker. The

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• as prepared by controlled living ring-opening metathesis polymerization (ROMP) of the respective metal-incorporating monomers. Ferrocene- and other metallocene-modified polymers, macromolecules including metal-carbonyl complexes, polymers tethering early or late transition metal complexes, etc. are

• synthesis of these targets presently accessible through controlled and living polymerization techniques including controlled radical polymerizations (CRP) such as atom transfer radical polymerization (ATRP), nitroxide-mediated polymerization (NMP) and reversible addition–fragmentation chain transfer (RAFT

• ) polymerization [15][16], living ionic polymerizations, specifically ring-opening polymerization (ROP) [17], as well as migration insertion polymerization (MIP) [18], acyclic diene metathesis polymerization (ADMET) [19][20] and ring-opening metathesis polymerization (ROMP) [21][22][23][24][25][26][27]. These

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• the observed product (Scheme 9). While the reaction conditions are similar to those utilized in atom transfer radical addition and polymerization reactions, the use of excess amine was critical for a robust alkenylation reaction and to avoid atom transfer and polymerization products. Various electron

• and supress polymerization. A detachable ester group can be utilized in order to achieve Z-selective alkene synthesis [37]. In this protocol, an ortho-hydroxy substituted styrene undergoes esterification with a labile α-bromo ester. This positions the reactive radical exclusively on the face of the

• . While the groundwork for this recent surge was laid in the development of atom-transfer radical addition and polymerization chemistry, the realization of its potential in alkylation chemistry will greatly expand the use of copper catalysis as a means for constructing complex molecular architectures. The

Self-assemblies of γ-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine

• Jing Lin,
• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2015, 11, 2267–2277, doi:10.3762/bjoc.11.247

• Jing Lin Tao Kong Lin Ye Ai-ying Zhang Zeng-guo Feng School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China 10.3762/bjoc.11.247 Abstract Pentablock copolymers PMA-PPO-PEO-PPO-PMA synthesized via atom transfer radical polymerization (ATRP) were self

• ratio of 30 was maintained after the second in situ ATRP. However, the degree of polymerization (DP) of PMPC for all the copolymers was increased with the feed molar ratio of MPC to PEP40M, clearly suggesting that PEP40M30CD as an initiator in the form of PPR indeed held a very high degree of chain-end

• PMDETA (0.8 mmol) were added to the mixture and then quenched in liquid nitrogen. Before 79.2 mg CuCl (0.8 mmol) was added, the system was degassed with three freeze–vacuum–thaw cycles and purged with nitrogen. Then the reactor was sealed under vacuum and the polymerization started under stirring for 48

Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

• Stefan Naumann,
• Johannes Klein,
• Dongren Wang and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 2261–2266, doi:10.3762/bjoc.11.246

• of Textile Chemistry and Chemical Fibers, Körschtalstrasse 26, D-73770 Denkendorf, Germany 10.3762/bjoc.11.246 Abstract The polymerization of octamethylcyclotetrasiloxane (D4) is investigated using several five-, six- and seven-membered N-heterocyclic carbenes (NHCs). The catalysts are delivered in

• situ from thermally susceptible CO2 adducts. It is demonstrated that the polymerization can be triggered from a latent state by mild heating, using the highly nucleophilic 1,3,4,5-tetramethylimidazol-2-ylidene as organocatalyst. This way, high molecular weight PDMS is prepared (up to >400 000 g/mol

• , 1.6 < ÐM < 2.5) in yields >95%, using low catalyst loadings (0.2–0.1 mol %). Furthermore, the results suggest that a nucleophilic, zwitterionic mechanism is in operation, in preference to purely anionic polymerization. Keywords: latency; N-heterocyclic carbenes; ring-opening organocatalysis

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• toolbox [1][2][3][4][5][6]. Since its infancy in the 50’s, metathesis has grown in importance and, today, applications in a broad variety of areas such as natural product synthesis [7][8][9][10][11], polymerization [12], drug discovery [7], petrochemistry or agricultural chemistry have been reported. One

Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case

• Karina Mroczyńska,
• Małgorzata Kaczorowska,
• Erkki Kolehmainen,
• Ireneusz Grubecki,
• Marek Pietrzak and
• Borys Ośmiałowski

Beilstein J. Org. Chem. 2015, 11, 2105–2116, doi:10.3762/bjoc.11.227

• polymerization needs properly prearranged monomers with intermolecular hydrogen bonding patterns fitting between molecules. In this sense the conformational freedom is a main limiting factor in molecular design. On the other hand in forms stabilized by an intramolecular hydrogen bond it is possible to break an

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• metal-catalyzed alkene metathesis [1][2][3][4][5][6][7][8][9][10], which involves a fragment exchange between alkenes, is nowadays one of the most used strategies for the formation of carbon–carbon bonds. This area of study began with a “black box” approach for catalysts formation in polymerization of

• -workers synthesized the first well-defined ruthenium(II) complex (5, Scheme 2) bearing a carbene moiety, able to perform ring-opening metathesis polymerization (ROMP) reactions of low-strained olefins [34][35] and ring-closing metathesis (RCM) reactions of functionalized dienes [36]. In the solid state

• and isolated yield in parentheses. aIsolated as a mixture, NMR yield. bToluene (0.5 mL). cE/Z ratio determined by 1H NMR. Synthesis of Schiff base-ruthenium complexes. Veerport's indenylidene Schiff-base complexes. Polymerization of 7-oxanorbornene in water. Synthesis of the first well-defined

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

• )-4,5-dihydroimidazol-2-ylidene). Catalysts 11 and 12 are additionally ligated by two pH-responsive DMAP ligands. The crystal structure was solved for complex 12 by X-ray diffraction. In organic, neutral solution, the catalysts are capable of performing standard ring-opening metathesis polymerization

• the polymerization process. Furthermore, the coagulate content for all experiments stayed <2%. This represents an unprecedented efficiency in emulsion ROMP based on hydrophilic ruthenium alkylidene complexes. Keywords: activation; aqueous catalysis; emulsion; olefin metathesis; polymerization

• ][51][52][53] and/or solubilization [31][32] in aqueous media. One of the most intriguing applications of water-soluble metathesis catalysts is the production of latexes via ring-opening metathesis polymerization (ROMP) in emulsion. However, to date very few reports have successfully employed well

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• this mechanism, synthetic polycarbonates arising from organocatalytic ring-opening polymerization of cholesterol monomers were reported to create self-assemblies possessing high interior charge density and wide spectrum antimicrobial activity [6]. Interestingly, the causative vector of human gastritis

Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• -opening metathesis polymerization (ROMP) can be minimized by carrying out the reaction in high dilution. Furthermore good yields of ROCM products can be obtained only when an 1.5-fold excess of a cross olefin is used [14][19][20]. Results and Discussion Now, we wish to report our preliminary results of

• and their E/Z stereochemistry was studied. Our results seem to be in some contradiction to the commonly accepted opinion that ROCM reactions should be carried out in high dilution to avoid polymerization. It was found that ROCM reactions proceed quite efficiently even under neat conditions

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• double bond transformations by olefin metathesis have significantly impacted organic and polymer synthesis over the last two decades [1][2][3]. If early works focused on ring-closing metathesis and ring-opening metathesis polymerization, progresses in catalysts performances [4][5] and selectivity have

Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

• Yulia I. Denisova,
• Maria L. Gringolts,
• Alexander S. Peregudov,
• Liya B. Krentsel,
• Ekaterina A. Litmanovich,
• Arkadiy D. Litmanovich,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2015, 11, 1796–1808, doi:10.3762/bjoc.11.195

• course of polymerization but also through chemical modification of macromolecules [1]. In particular, main-chain polyesters and polyamides are capable of cross-reactions (also known as interchange reactions) characterized by the rearrangement of macromolecular backbones via break up and the formation of

• and PCOE are commonly synthesized by ring-opening metathesis polymerization (ROMP). PNB is a well-known commercial product available under the trademark Norsorex® [8][16], which is mainly used as a solidifier of oil and solvent for the complete absorption of oil or other hydrocarbons. PCOE, known as

• reduction of the polymerization activity of NB through introducing substituents into its molecule [26][27][28]. Therefore, the cross-metathesis of PCOE and PNB can be considered as a novel way to statistical NB-COE copolymers. In the present article we try to gain more insight into this reaction by

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• , H2ITapMe2 = 1,3-bis(2’,6’-dimethyl-4’-trimethylammoniumphenyl)-4,5-dihydroimidazol-2-ylidene, OTf− = CF3SO3−) based on a dicationic N-heterocyclic carbene (NHC) ligand was prepared. The reactivity was tested in ring opening metathesis polymerization (ROMP) under biphasic conditions using a nonpolar organic

• are introduced via anion metathesis [13][14]. These novel catalytic systems have successfully been used under SILP conditions [11][15]. Furthermore, they allow running ring-opening metathesis polymerization (ROMP) reactions under biphasic conditions, an approach that offers access to both ROMP-derived

• organic phase (see Supporting Information File 1). It is thus also in line with the fact that Ru–alkylidenes based on electron-rich NHCs, e.g., based on tetrahydropyrimidin-2-ylidenes [23], strongly promote olefin metathesis. Biphasic ring-opening metathesis polymerization (ROMP) reactions To test the

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

• polymerization of tubulin in vitro. The same methodology might be applied to direct a drug by conjugation to a molecule binding to a specific receptor on cancer cells. Moreover, by using dicarboxylated linkers with a disulfide bridge, it was possible to generate dynamic libraries of dimeric hybrids based on

• traditional polymerization methods [52]. Binns et al. summarized the attempts to scale up synthesis of polyesters by enzyme catalyzed polycondensation of adipic acid and hexane-1,6-diol in a very well-worth reading article [53]. They discussed the very slow progress in achieving high molecular weight polymers

• and concluded that removal of the leaving group, water, to draw the equilibrium towards polymerization, and the reversal nature of lipase catalysis are two main obstacles. Others have pointed out the latter also [54]. Often a two-step procedure has been used, an initial polymerization to achieve

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

• carboxylic acids RCO2H release radicals (R•) in the photo-Kolbé reaction was referred to above. Ni and co-workers showed that vinyl acetate polymerization could be mediated by TiO2 nanoparticle photocatalyzed reactions with carboxylic acids [50]. Kinetic studies established that amongst simple carboxylic

• with optically pure amino acids probably because the released radicals were planar, or close to planar. Radical additions took place to other alkene substrates such as acrylamide but extensive polymerization was observed with methyl methacrylate. The phenoxyacetic acid/acrylamide reaction was chosen to

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

• (Figure 1) [25][26][27][28][29][30][31][32][33][34]. The latent behavior exhibited by cis-Caz-1 can be of interest in fields such as polymer chemistry, where its thermally-switchable properties can be used to inhibit polymerization during the storage of monomer-catalyst mixtures, and/or to initiate

• polymerization on demand through use of a stimulus [35][36]. The use of this catalyst in the ring-closing metathesis (RCM) reaction gave excellent conversions of challenging substrates, even at low catalyst loadings. The high activity and robustness of cis-Caz-1 is derived from synergistic effects between the σ

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• aromatics using THF-d8 was reported [88]. We explain the reduced yield of 6-D (48% yield) and the formation of tar products by hydrogen atom abstraction from 3 or 6 and subsequent polymerization. No significant amounts of double deuterated products were detected. The kinetic isotope effect was determined

Thermal properties of ruthenium alkylidene-polymerized dicyclopentadiene

• Yuval Vidavsky,
• Yotam Navon,
• Yakov Ginzburg,
• Moshe Gottlieb and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2015, 11, 1469–1474, doi:10.3762/bjoc.11.159

• Differential scanning calorimetry (DSC) analysis of ring opening methatesis polymerization (ROMP) derived polydicyclopentadiene (PDCPD) revealed an unexpected thermal behavior. A recurring exothermic signal can be observed in the DSC analysis after an elapsed time period. This exothermic signal was found to be

• : glass-transition temperature; polydicyclopentadiene; ring opening metathesis polymerization; ruthenium-catalyzed olefin metathesis; thermoset polymers; Introduction Olefin metathesis [1][2][3][4][5][6] has advanced to become a major synthetic tool in academia [7][8][9][10][11] and industry [12

• ]. Metathesis polymerization techniques [13][14][15], and especially ring opening metathesis polymerization (ROMP) [16][17], have had a vital role in this growth. Polydicyclopentadiene (PDCPD), probably the most widely used metathesis polymer, is formed through ROMP of mostly endo-dicyclopentadiene (DCPD, 1

Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity

• Karolina Żukowska,
• Eva Pump,
• Aleksandra E. Pazio,
• Krzysztof Woźniak,
• Luigi Cavallo and
• Christian Slugovc

Beilstein J. Org. Chem. 2015, 11, 1458–1468, doi:10.3762/bjoc.11.158

• initiators in ROMP In the next step, compounds 5a, 14 and 15 were tested as initiators in ring-opening metathesis polymerization (ROMP). The active species in ROMP (i.e., the propagating species) can be considered more stable than the methylidene intermediate in RCM, particularly when norbornenes such as

• ,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diethyl ester (22) or dicylcopentadiene (23) were used (cf. Figure 7). A distinctly changed initiation trend was observed under these reaction conditions. Initiator 5a started the polymerization at the lowest temperature (onset of the polymerization

• exotherm at approx. 60 °C; cf. Figure 9, left) while the highest latency was found for initiator 14 (onset at approx. 75 °C). While initiators 14 and 15 exhibited rather sharp exotherms for the polymerization of monomer 22, a much broader shape was found in the case of 5a. This shape can be explained by

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

• Ana Čikoš,
• Irena Ćaleta,
• Dinko Žiher,
• Mark B. Vine,
• Ivaylo J. Elenkov,
• Marko Dukši,
• Dubravka Gembarovski,
• Marina Ilijaš,
• Snježana Dragojević,
• Ivica Malnar and
• Sulejman Alihodžić

Beilstein J. Org. Chem. 2015, 11, 1447–1457, doi:10.3762/bjoc.11.157

• ]. A previously mentioned example of a protein phosphatase inhibitor okadaic acid is a toxin associated with diarrheic shellfish poisoning [28]. Another example are structurally complex tubulin polymerization-inhibiting macrolides such as spongistatins, a family of compounds isolated from marine

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• lamp in deuteriochloroform. The only process that we could observe was a “polymerization” reaction, which slowly destroyed the substrate. Likewise, no photocyclization to the divinylcyclobutene derivate 51 was noted. [2 + 2] Photodimerizations of olefins have often been described, whether in solution

Quarternization of 3-azido-1-propyne oligomers obtained by copper(I)-catalyzed azide–alkyne cycloaddition polymerization

• Shun Nakano,
• Akihito Hashidzume and
• Takahiro Sato

Beilstein J. Org. Chem. 2015, 11, 1037–1042, doi:10.3762/bjoc.11.116

• –alkyne cycloaddition (CuAAC) polymerization, were quarternized quantitatively with methyl iodide in sulfolane at 60 °C to obtain soluble oligomers. The conformation of the quarternized oligoAP in dilute DMSO-d6 solution was examined by pulse-field-gradient spin-echo NMR based on the touched bead model

• . Keywords: 3-azido-1-propyne oligomer; CuAAC polymerization; hydrodynamic radius; methyl iodide; pulse-field-gradient spin-echo NMR; quarternization; Introduction The copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) efficiently yields 1,4-disubstituted-1,2,3-triazole from rather stable azides and

• dipole moment and aromaticity, 1,2,3-triazole itself may be a functional group. Polymers composed of dense 1,2,3-triazole moieties on the backbone are thus promising as functional materials. Recently, we have investigated the CuAAC polymerization of 3-azido-1-propyne (AP) using 3-bromo-1-propyne as a

Radical-mediated dehydrative preparation of cyclic imides using (NH₄)₂S₂O₈–DMSO: application to the synthesis of vernakalant

• Dnyaneshwar N. Garad,
• Subhash D. Tanpure and
• Santosh B. Mhaske

Beilstein J. Org. Chem. 2015, 11, 1008–1016, doi:10.3762/bjoc.11.113

• synthesis of imides from the combination of aliphatic amines and unsaturated anhydrides. Plausibly, the intermediate amic acid in these cases may be prone to decarboxylation [57] and radical polymerization similar to the acrylamide polymerization using APS as a radical initiator [55]. Encouraged by this

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

• dendritic structure of hPG can be expected to limit the flexibility of attached ligands compared to a linear polymer and might induce a more globular arrangement of the ligands. The hPG polymer carrier was synthesized via an anionic ring-opening polymerization of glycidol [20] and also modified with