Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• ][109][110][111][112][113]. Organic peroxides are widely used as oxidants in oxidative coupling processes [114][115][116][117][118][119][120]. Industrial-scale production of readily available and efficient initiators of free radical polymerization and effective biologically active compounds promotes the

Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

• Helmut Ritter,
• Monir Tabatabai and
• Markus Herrmann

Beilstein J. Org. Chem. 2016, 12, 245–252, doi:10.3762/bjoc.12.26

• )-amino-protected monomers 2-((1-bromo-2-methylpropan-2-yl)oxycarbonylamino)ethyl (meth)acrylate 3a,b. For this purpose, 2-isocyanatoethyl (meth)acrylate 1a,b was reacted with 1-bromo-2-methylpropan-2-ol (2a). The free radical polymerization of (Br-t-BOC)-aminoethyl (meth)acrylates 3a,b yielded poly((Br-t

• . Carpino [8][9][10] and a first practical application in peptide synthesis [11] this protecting group was quasi forgotten. In the present work we report new Br-t-Boc-protected (meth)acrylic monomers and their polymerization through free radical polymerization. The kinetics of Br-t-BOC solvolysis of the

• , IR, GPC and DSC methods. The kinetics of the deprotection step was followed by 1H NMR spectroscopy. The solvent polarity and neighboring group effects on the kinetics of deprotection are discussed. Keywords: amino group protection; bromo-tert-butyloxycarbonyl; deprotection; free radical

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

• 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

• the atom-transfer radical polymerization of methyl methacrylate or styrene to obtain poly(methyl methacrylate) and polystyrene devoid of colored traces of catalyst, a very important requirement for special applications, e.g., in dentistry, medical devices, housewares, and food packaging. In another

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

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

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• cannot be homopolymerized through free radical polymerization, meaning that only single CA units will be attached to the PEG chains [14]. However, other phenomena may also affect the resulting grafting density such as different tendency of grafting from and grafting to between the different monomers

• case of CA it is generally believed that it cannot be homo polymerized via free radical polymerization [14]. CA contains a 1.2-disubstituted ethylene exhibiting high steric hindrance, which might explain the low reactivity compared to the MA and AA. Therefore, radicals at the β-carbon may not be able

• hydrogen from the polymer surface to generate surface radicals. In the presence of α,β-unsaturated carboxylic acids, the macroradical initiates grafting via the radical-polymerization mechanism. Variation of the crotonic acid and benzophenone concentration and its influence on the grafting. The

Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA

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

Beilstein J. Org. Chem. 2014, 10, 2461–2469, doi:10.3762/bjoc.10.257

• 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.10.257 Abstract A pentablock copolymer was prepared via the atom transfer radical polymerization of 2-hydroxyethyl methacrylate (HEMA

• knowledge, self-assembled PPRs from γ-CDs with the bulkier poly(2-hydroxyethyl methacrylate) (PHEMA)-flanked block copolymers have not yet been reported. Herein, a pentablock copolymer PHEMA-PPO-PEO-PPO-PHEMA is prepared via atom transfer radical polymerization (ATRP) in DMF, and allowed to self-assemble

A promising cellulose-based polyzwitterion with pH-sensitive charges

• Thomas Elschner and
• Thomas Heinze

Beilstein J. Org. Chem. 2014, 10, 1549–1556, doi:10.3762/bjoc.10.159

• the same monomer unit [1]. The first statistical, synthetic polyampholytes were obtained in the 1950s by radical polymerization of acrylic- or methacrylic acid and their derivatives [5][6][7]. 20 years later the first block polyampholytes were synthesized via anionic polymerization of 2-vinylpyridine

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

• others, free radical polymerization of C-6 of the glucosamine residues with poly(ethylenglycol) acrylate [58]; free-radical polymerization of C-1 of glucosamine with mPEG [59] and 1,3-dipolar cycloaddition between the azide of an N-azidated chitosan and mPEG derivatives containing a triazolyl moiety [60

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• materials [15], optical and electro-optical materials [16][17], fabrication of devices and materials [18], adhesives and sealants [19], coatings [20] and surface modifications [21][22]. The great interest in PRG application to free radical polymerization (FRP) has led to the development of two major classes

• •+. Generally, A•− and D•+ will give rise to initiating radicals for free radical polymerization, to hydrogen by water reduction or oxygen by water oxidation [6][7][8], etc. In an ideal case, a photocatalytic behavior is ensured when there is enough redox donor to make the dye surviving during a long period of

• -initiator of lowest concentration, in the present case the acceptor TA. All this phenomena explain the synergistic effect observed in some free radical polymerization. Radical and photolysis quantum yields As for the Type II systems, in order to quantify the catalytic behavior of the dye, the quantum yield

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

• anion. Later on, other amines (N,N-diisopropylethylamine, N,N-dimethylformamide) and bromides (ethyl 2-bromoisobutyrate, benzyl bromide) were proposed for the photocatalytic radical polymerization of various methacrylates [53]. Ir complexes can also be used. As only carbon centered radicals can be

• developing new PICs with improved or extended light absorption properties. The PIC/MDEA/alkyl halide The performance of the new proposed PIC for a reductive cycle in combination with an amine (MDEA) and an alkyl halide (phenacyl bromide; R–Br) to initiate a radical polymerization has been also checked. In

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• –ene [28], thiol–isocyanate [29] and others are used. Thereby most studies have in common that synthesis of the polymer with thermo-responsive properties is preferably accomplished by either living anionic polymerization, or controlled radical polymerization [18][21][22][24][29][30][31][32][33][34

• Supporting Information File 1, Figures S1 to S4 for the 1H and 13C NMR data). Synthesis of the end-group functionalized polymers. The thiol functionalized 4-alkylphenols (6a and 6b) were used as chain transfer agents (CTA) for the free-radical polymerization of N,N-diethylacrylamide (DEAAm) (7) (see Scheme 2

• % seemed to be a reasonable concentration since Idziak et al. [42] showed that a variation of the polymer concentration of PDEAAm (obtained in a free-radical polymerization with AIBN as initiator) in the range of 0.5 wt % up to 20 wt % does not considerably affect the LCST. All obtained polymers (8a–d, 9a

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• initialize radical polymerization of HEA. Because of ring strain, cyclopropanes are prone to ring opening via cleavage of one of the three C–C bonds. The resulting reactive intermediates have been shown to participate in a number of synthetic/mechanistic applications [103][104]. One of these applications is

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

• Rajesh Munirathinam,
• Roberto Ricciardi,
• Richard J. M. Egberink,
• Jurriaan Huskens,
• Michael Holtkamp,
• Herbert Wormeester,
• Uwe Karst and
• Willem Verboom

Beilstein J. Org. Chem. 2013, 9, 1698–1704, doi:10.3762/bjoc.9.194

• a flat silicon oxide surface in order to optimize the reaction conditions before attempting the functionalization of a microreactor. Polystyrene sulfonate (PSS) polymer brushes [19] were synthesized according to the procedure summarized in Scheme 2. First, a monolayer of atom transfer radical

• polymerization (ATRP) initiator was covalently anchored on silicon oxide substrates [20]. Then, a solution of styrene sulfonate in methanol/water (1:3) in the presence of 2-2’-bipyridyl and CuBr, was used to grow the PSS polymer brushes by means of ATRP. After activation of the polymer brushes with 1 M HCl, they

Organotellurium-mediated living radical polymerization under photoirradiation by a low-intensity light-emitting diode

• Yasuyuki Nakamura and
• Shigeru Yamago

Beilstein J. Org. Chem. 2013, 9, 1607–1612, doi:10.3762/bjoc.9.183

• diode (LED) effectively activated an organotellurium chain transfer agent and the dormant species, promoting well-controlled radical polymerization. The use of the LED provided many advantages over the previously reported high-intensity Hg lamp, including high energy efficiency during the polymerization

• -emitting diode; living radical polymerization; organotellurium compound; photopolymerization; tellurium; visible light; Introduction Living radical polymerization (LRP) is one of the most powerful methods for the synthesis of structurally well-defined polymers because of its robustness and high

• been widely employed in conventional radical polymerization for various applications such as coatings, adhesives, gels and microelectronics [4][5][6][7]. The major motivation for the utilization of photochemistry in LRP is that it enables the dormant species to be activated under mild thermal

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• polysaccharide backbone. This last method is the most convenient one as it is less sensitive to steric hindrance problems, which can limit the grafting process. The development of controlled/living radical polymerization (CLRP) techniques, such as atom transfer radical polymerization (ATRP) [4][5][6][7

The synthesis of well-defined poly(vinylbenzyl chloride)-grafted nanoparticles via RAFT polymerization

• John Moraes,
• Kohji Ohno,
• Guillaume Gody,
• Thomas Maschmeyer and
• Sébastien Perrier

Beilstein J. Org. Chem. 2013, 9, 1226–1234, doi:10.3762/bjoc.9.139

• Sustainability, School of Chemistry, The University of Sydney, NSW 2006, Australia 10.3762/bjoc.9.139 Abstract We describe the use of one of the most advanced radical polymerization techniques, the reversible addition fragmentation chain transfer (RAFT) process, to produce highly functional core–shell particles

• , and we demonstrate that the exceptional control over their dimensions is achieved by careful tailoring the conditions of the radical polymerization. Keywords: core–shell particles; free radical; grafting; RAFT polymerization; silica; Introduction The versatility of organic free radical chemistry in

• applications. The establishment in the 1990s of living radical polymerization (LRP, defined as reversible deactivation radical polymerization by the IUPAC), has dramatically changed the polymer-synthesis landscape allowing the easy production of well-defined polymeric materials of desired molecular weights

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• (PI) [1]. These PIs are usable in two scenarios, both of which are light induced. Firstly, they are usable in free radical polymerization (FRP), where the PIs work as either cleavable type I PIs or uncleavable type II PIs in dependence of couples formed by the PI and hydrogen or electron donors (r1 in

• to radical polymerization. Laser flash photolysis Upon laser excitation of Py_3 at 355 nm, a triplet state T1 characterized by a maximum absorption at ~420 nm and a rather long lifetime is formed (t > 4 μs) (Figure S2 in Supporting Information File 1). This T1 state is similar to that of Py_1 [31

• shadow areas. Free radical photopolymerization (FRP) Typical free radical polymerization profiles of TMPTA upon the Xe–Hg lamp exposure in laminate by using the Co_Py/MDEA (or PBr) two-component PISs are represented in Figure 9. In the presence of Co_Py alone, FRP occurs but the inhibition time is high

Cyclodextrin-induced host–guest effects of classically prepared poly(NIPAM) bearing azo-dye end groups

• Gero Maatz,
• Arkadius Maciollek and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 1929–1935, doi:10.3762/bjoc.8.224

• controlled conditions such as reversible addition–fragmentation chain-transfer polymerization (RAFT) or atom-transfer radical polymerization (ATRP) [14][15][16]. However, up to now, only a little is known about the preparation of dye-end-group-labeled polymers by using classical free-radical polymerization

• topology, attract considerable interest for a wide range of optical, medical or reagent-immobilization applications [16]. Results and Discussion Here, we describe the free-radical polymerization of N-isopropylacrylamide (NIPAM, 1) in the presence of a chain–transfer agent and its end-group

• interpreted by the hydrophobic shell of 8 and the strong hydrophobic interaction above the LCST, which causes the formation of the large particles. Conclusion In summary, we have presented the synthesis of an azo-dye-end-group-labeled PNIPAM by free-radical polymerization. The acidochromic and thermo

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• ; cyclodextrins; graft copolymer; macromonomer; ring-opening free radical polymerization; 2-vinylcyclopropane; Introduction Macromonomers are polymers or oligomers with at least one functional end group that is capable of further polymerization. The molecular weight of macromonomers generally ranges between 1000

• to Scheme 3. The intermediate amino-terminated poly(NiPAAm) 3 was obtained from the reaction of NiPAAm (1) and 2-aminoethanethiol hydrochloride (2) via radical polymerization either in water using 2 and ammonium persulfate as redox initiator [34] or in ethanol using 2,2’-azobis(isobutyronitrile

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• terminal functionality. Table 16 summarizes the structures, SHG coefficients d33, and stability parameters Tg and TD. It is obvious that the three cross-linked nonlinear optical polymers 141–143, prepared by radical polymerization, possess much higher nonlinearities than the two-component polymers 135–140

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• compound was first reported in 2005 by Severin et al. who successfully used it as a catalyst for atom transfer radical addition (ATRA) and cyclization (ATRC) reactions [4][5]. In 2007, we further extended its application field to the related process of atom transfer radical polymerization (ATRP) [2

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• , polyaddition, polycondensation, and modifications of polymers, and the trends followed in this research field. The so-called “artificial miniemulsions”, i.e., the miniemulsion of preformed polymer, are not described in this review. Free-radical polymerization Most of the reported polymer syntheses in

• miniemulsion are performed via free-radical polymerization. In fact, the polymerization is very simple to perform and yields are usually high. Moreover, the polydispersity in size of the miniemulsion particles and the dispersity of the polymer are not directly correlated, and for applications the focus is in

• of the monomer. The polymerization of hydrophilic monomers in inverse miniemulsions was recently reviewed by Capek [16]. The functional groups that can be introduced in latexes by free-radical polymerization in inverse miniemulsion are overviewed in Table 2. Homopolymers of crosslinked

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• chlorine groups for subsequent initiation of atom transfer radical polymerization (ATRP). Oligo(ethylene glycol) methyl ether methacrylates with different length of the hydrophilic side chain are used as the main monomer to generate a hydrophilic polymer shell with tunable critical solution behavior in

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• a conjugated main chain and nonlinear optically active (nlo) chromophores in the side chain. DPP was incorporated in the polymers as a sensitizer for charge carrier generation. Some years later, Eldin and coworkers described DPP-containing polymers obtained by radical polymerization of bis-acryloyl