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

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• used to functionalize the existing polyarenes and/or to extend them to larger PAHs. The most common class of reactions is the electrophilic aromatic substitution; however, free radical, nucleophilic addition, reduction, and oxidation reactions are also possible. To synthesize larger PAHs that are not

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

• introduced into the polymer photochemistry field (area) in the very past years (see a review in [15][16][17][18][19][20][21][22]). Indeed, in this area, free-radical photopolymerization (FRP, Scheme 1, reactions 1 and 2), cationic photopolymerization (CP, Scheme 1, reactions 3 and 4), free-radical promoted

• sources: Several lights were used: 1) polychromatic light from a halogen lamp (Fiber-Lite, DC-950 – incident light intensity: I0 ≈ 12 mW/cm2; in the 370–800 nm range); 2) monochromatic light delivered by a laser diode at 532 nm (I0 ≈ 100 mW/cm2) and 3) LEDs at 514 nm. iii) Free radical photopolymerization

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

• synthesis of thermo-, oxidation- and cyclodextrin- (CD) responsive end-group-functionalized polymers, based on N,N-diethylacrylamide (DEAAm). In a classical free-radical chain transfer polymerization, using thiol-functionalized 4-alkylphenols, namely 3-(4-(1,1-dimethylethan-1-yl)phenoxy)propane-1-thiol and

• ]. Some publications make use of free-radical chain transfer polymerization and subsequent polymer post-modification [25][27][35][36]. The scope of our investigation was the preparation of multiple-stimuli-responsive PDEAAm polymers possessing hydrophobic end-groups suitable for host–guest interactions

• using classical free-radical chain transfer polymerization techniques. These polymers contain oxidation-sensitive thioether linkages. Up to now, to the best of our knowledge, the simultaneous influence of oxidation and cyclodextrin-sensitive end-groups on the solution properties of poly(N,N

3-Pyridinols and 5-pyrimidinols: Tailor-made for use in synergistic radical-trapping co-antioxidant systems

• Luca Valgimigli,
• Daniele Bartolomei,
• Riccardo Amorati,
• Evan Haidasz,
• Jason J. Hanthorn,
• Susheel J. Nara,
• Johan Brinkhorst and
• Derek A. Pratt

Beilstein J. Org. Chem. 2013, 9, 2781–2792, doi:10.3762/bjoc.9.313

• phenolic antioxidants, but which are equally efficacious as the 3-pyridinol/5-pyrimidinol antioxidants alone at higher loadings. Keywords: antioxidants; autoxidation; free radical; phenols; 3-pyridinols; 5-pyrimidinols; Introduction Radical-trapping (chain-breaking) antioxidants are arguably the most

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

• , USA 10.3762/bjoc.9.312 Keywords: free radical; Long-thriving movements often have a habit of continually reinventing themselves in a process called renaissance. The word itself is an English reinvention (some would say theft) of the French word for “rebirth”. Renaissances often occur in waves with

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• multigramme scale using a free radical procedure. A phase transfer catalysed fluorination transformed these species to the 4-fluorobut-2E-enoates reproducibly and at scale (48–53%, ca. 300 mmol). Asymmetric dihydroxylation reactions were then used to transform the butenoate, ultimately into all four

The total synthesis of D-chalcose and its C-3 epimer

• Jun Sun,
• Song Fan,
• Zhan Wang,
• Guoning Zhang,
• Kai Bao and
• Weige Zhang

Beilstein J. Org. Chem. 2013, 9, 2620–2624, doi:10.3762/bjoc.9.296

• ,THF, rt, 96%; (b) AD-mix-β, t-BuOH/H2O, 0 °C, 80%; (c) TEMPO, NaClO, CH2Cl2, −5 °C. AD = asymmetric dihydroxylation, TEMPO = 2,2,6,6-tetramethyl-1-piperidinyloxy, free radical. Reagents and conditions: (a) PhCH(OCH3)2, PPTS, CH2Cl2, rt; (b) DIBAL-H, CH2Cl2, 0 °C, 76% in two steps. PPTS = pyridinium p

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• liberates the palladium catalyst. Experiments carried out by the authors were inconsistent with an alternative purely free radical pathway, but could not rule out caged and/or “Pd-associated” radical intermediates. Another study by Y. H. Budnikova et al. described the electrochemical perfluoroalkylation of

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

• are emerging as a powerful tool in amine synthesis. This article reviews synthetic applications of amine radical cations produced by visible light photocatalysis. Keywords: α-amino radical; amine radical cation; catalysis; distonic ion; free radical; iminium ion; photoredox; visible light

• [61][62]. α-Amino radical 3 is strongly reducing [45][63], thus making the second one-electron oxidation facile. The last mode involves cleavage of a C–C bond α to the nitrogen atom, yielding a neutral free radical 6 and iminium ion 5. Iminium ion 4, an excellent electrophile, is amenable to

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• Catrin Goeschen Uta Wille ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry and Bio21 Institute, The University of Melbourne, 30 Flemington Road, Parkville, VIC 3010, Australia 10.3762/bjoc.9.225 Abstract Manufactured polymer materials are used in

• polymers, the mechanism of their degradation upon exposure to environmental oxidants is barely understood. In this work, model systems of important structural motifs in commercial high-performing polyesters were used to study the reaction with the night-time free radical oxidant NO3• in the absence and

• the strongest free-radical oxidants known [E(NO3•/NO3−) = 2.3–2.5 V vs NHE] [9], and recent product studies by us revealed that NO3• readily damages aromatic amino acids and pyrimidine nucleosides through an oxidative pathway [10][11][12][13]. Thus, the ease by which model compounds of biologically

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• excellent stereoselectivity, and only trans-isomers are obtained. Keywords: alkenylation; cycloalkanes; decarboxylative; Fe(acac)3; free radical; sp3 C–H bonds; Introduction Direct C–H functionalization has become one of the most useful and attractive tools in organic chemistry because it can construct

Aerobic radical multifunctionalization of alkenes using tert-butyl nitrite and water

• Daisuke Hirose and
• Tsuyoshi Taniguchi

Beilstein J. Org. Chem. 2013, 9, 1713–1717, doi:10.3762/bjoc.9.196

• γ-lactols, whereas the reaction in the presence of water produces 4-hydroxy-5-nitropentyl nitrate or 4-hydroxy-3-nitropentyl nitrate derivatives. Keywords: C−H oxidation; free radical; nitration; oxygen; radicals; water; Introduction Multifunctionalization reactions of simple organic molecules are

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• : bromination; free radical; hydrocarbon; light-emitting diode; photo irradiation; Introduction Bromination reactions of organic compounds are fundamental reactions for providing a wide variety of organic precursors for industrial materials [1][2][3][4][5][6][7][8]. Generally, the bromination of saturated

Anodic coupling of carboxylic acids to electron-rich double bonds: A surprising non-Kolbe pathway to lactones

• Robert J. Perkins,
• Hai-Chao Xu,
• John M. Campbell and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2013, 9, 1630–1636, doi:10.3762/bjoc.9.186

• not appear to be a significant competing pathway. Experimental results indicate that oxidation occurs at the olefin and that the reaction proceeds through a radical cation intermediate. Keywords: carboxylic acid; cyclization; electrolysis; free radical; kolbe; radical cation; Introduction Anodic

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• indanes or dihydrobenzofurans are too slow to be useful synthetically. Keywords: aromatic substitution; computational chemistry; DFT-D3; free radical; polar effects; radical reaction; Introduction The development of efficient catalytic reactions is one of the central issues of chemistry [1][2]. Radical

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

• , and easy availability of the low-cost light source. Structurally well-defined poly(methyl methacrylate), poly(methyl acrylate), and polystyrene, with narrow molecular weight distributions, were synthesized under LED irradiation with or without a neutral density filter. Keywords: free radical; light

Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds

• Brian M. Casey,
• Dhandapani V. Sadasivam and
• Robert A. Flowers II

Beilstein J. Org. Chem. 2013, 9, 1472–1479, doi:10.3762/bjoc.9.167

• radical intermediates. Furthermore, DFT computational studies were used to rationalize the observed site selectivity in the 2-tetralone products. Keywords: CAN oxidation; β-dicarbonyls; free radical; radical arylations; tetralones; Introduction 2-Tetralones are important intermediates or components of

Development of an additive-controlled, SmI₂-mediated stereoselective sequence: Telescoped spirocyclisation, lactone reduction and Peterson elimination

• Brice Sautier,
• Karl D. Collins and
• David J. Procter

Beilstein J. Org. Chem. 2013, 9, 1443–1447, doi:10.3762/bjoc.9.163

• Peterson elimination. The approach allows functionalised cyclopentanols containing two vicinal quaternary stereocentres to be conveniently prepared from simple starting materials. Keywords: cyclisation; free radical; Peterson elimination; reduction; samarium; telescoped process; Introduction Samarium

Diastereoselective radical addition to γ-alkyl-α-methylene-γ-butyrolactams and the synthesis of a chiral pyroglutamic acid derivative

• Tomoko Yajima,
• Eriko Yoshida and
• Masako Hamano

Beilstein J. Org. Chem. 2013, 9, 1432–1436, doi:10.3762/bjoc.9.161

• the reaction were also revealed. This stereoselective radical reaction was used for synthesis of chiral pyroglutamic acid derivatives starting from a commercially available chiral amino acid. Keywords: chelation controlled reaction; diastereoselective reaction; free radical; lactams; pyroglutamic

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• proposed. Keywords: copper(II) salt; cyclopropanol; electron transfer; free radical; radical ion probe; Introduction Radical ions are key intermediates in electron-transfer (ET) reactions of organic molecules [1][2][3][4][5] and they often undergo fragmentations to yield free radicals and ions [6][7][8

• ][26][28][29][30]. Careful examination of the reaction of probe II with FeCl3 revealed that a small quantity of the spirocyclic ketone was also formed [23][28]. This observation prompted us to explore the possibility that the free radical rearrangement route becomes more predominant when oxidizing

A construction of 4,4-spirocyclic γ-lactams by tandem radical cyclization with carbon monoxide

• Mitsuhiro Ueda,
• Yoshitaka Uenoyama,
• Nozomi Terasoma,
• Shoko Doi,
• Shoji Kobayashi,
• Ilhyong Ryu and
• John A. Murphy

Beilstein J. Org. Chem. 2013, 9, 1340–1345, doi:10.3762/bjoc.9.151

• azides with CO was achieved. The reaction of iodoaryl allyl azides, TTMSS and AIBN under CO pressure (80 atm) in THF at 80 °C gave the desired 4,4-spirocyclic indoline, benzofuran, and oxindole γ-lactams in moderate to good yields. Keywords: 4,4-spirocyclic indol γ-lactams; carbon monoxide; free radical

Preparation of optically active bicyclodihydrosiloles by a radical cascade reaction

• Koichiro Miyazaki,
• Yu Yamane,
• Ryuichiro Yo,
• Hidemitsu Uno and
• Akio Kamimura

Beilstein J. Org. Chem. 2013, 9, 1326–1332, doi:10.3762/bjoc.9.149

• : bicyclodihydrosilole; free radical; radical cascade reaction; SHi reaction; tris(trimethylsilyl)silane; Introduction Radical cyclization occupies a unique position in organic synthesis because it is a useful reaction for the construction of cyclic molecules [1][2][3][4][5][6][7][8][9][10]. The radical cascade

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• Abstract Since the beginning of the century, N-hydroxyphthalimide and related compounds have been revealed to be efficient organocatalysts for free-radical processes and have found ample application in promoting the aerobic oxidation of a wide range of organic substrates. When combined with different co

• M−1s−1 [19]) trapping trans,cis peroxyl radicals before they underwent β-fragmentation (Scheme 5). In accordance with this free-radical mechanism, Schmidt and Alexanian more recently reported the aerobic dioxygenation of alkenyl N-aryl hydroxamic acids (Scheme 6) [21]. In this case dioxygenation

• hydroperoxide intermediate, prolonging the free-radical chain [39][40][41]. The NHPI-activation by AQ has been also adopted by other research groups. Li and co-workers applied the NHPI/AQ system to promote the metal and solvent-free oxidation of α-isophorone to ketoisophorone, preventing the isomerization