Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• ) when C2–C8 alkenes (including isoprene) react with HO• in the presence of oxygen. In this process the generated β-hydroxyperoxy radicals subsequently react with NO affording β-hydroxy nitrates. The results from the Teng laboratory established that increasing the substitution pattern on the alkene

• suite of nitroxyalkylperoxy radicals. Worthy of note and a fundamental reason for initiating the UEA study was the fact that Schwantes et al. make reference to the fact that “synthetic standards are not available, the CIMS sensitivities for most of the isoprene nitrates formed in this work are not known

• “ [12]. Organic nitrates are important in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. It is generally accepted that transport models should include representation of organic aerosols derived from the reaction of monoterpenes with nitrate radicals. With this in mind

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• another report [39], the major products formed from triplet nitrenes are primary amines 4 through hydrogen-atom abstraction [58], secondary amines, 1,2-arylhydrazides and azo compounds 5, which are obtained by recombination of radicals [59]. Moreover, it was shown that yields of primary amines increased

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• and nano-reactor. The result is exceptionally high cage effects in which the two radicals that form within the capsule can only react with themselves. Moreover, these intimate contacts open up entirely new product landscapes by engendering rearrangement reactions not seen in solution. The flip-side of

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• mycobacteria for protection against foreign electrophilic agents such as oxidants, radicals, and drugs. In the detoxification pathway, MSH reacts with alkylating reagents and the resulting S-conjugates are subsequently cleaved at the amide bond by MSH S-conjugate amidase (Scheme 1) [4][5][6][7][8][9][10

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• appears that the size of the cavity is not the only parameter to take into account. Indeed, the ability of CDs to relay radicals towards the phosphorus atom might be tuned by the geometrical disposition of the hydroxy groups of CDs. The origin of the higher efficiency of β-CD on the photodegradation might

• be due to the presence of a strong hydrogen bond network between the secondary hydroxy groups, which restricts their degree of liberty, and lets them to relay the active radicals toward the phosphorus atom. Hydrolysis of chemical warfare agents Accelerating nerve agent’s hydrolysis, CDs are

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• intermediates resulting from the oxidation of FAs are monohydroperoxides, hydroperoxy-epidioxides, as well as peroxy-, alkoxy-, and alkyl radicals [16]. Further thermal degradation or fragmentation of these intermediates leads to odor-active carbonyl compounds such as aldehydes, ketones, alcohols and esters

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• increased antioxidant activity could be attributed to the encapsulation of 1 and 2 in CDs [51]. Inclusion in CD cavity could protect and stabilize the formed phenoxyl radicals after reaction with ABTS•+ leading to an enhanced activity by delaying its oxidation. It has been also demonstrated that CDs could

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

• used extensively in polymer chemistry because of the ability of alkyl radicals to participate in chain reactions [2][3][4]. They have also been used extensively in small molecule synthesis, particularly in an intramolecular cyclization setting [5][6][7][8][9]. However, while the ability of alkyl

• radicals to add to electron-rich π-systems is well established [10][11][12][13], harnessing this mode of reactivity to provide products of intermolecular alkylation would be highly valuable in organic synthesis. Although various metals have been shown to promote radical polymerizations, copper is by far

• nitronate anions are known to undergo alkylation with alkyl radicals, these radicals are often accessed using highly undesirable methods such as stoichiometric alkylmetal reagents or highly complex alkylating agents [17]. Although allylation [18][19][20][21][22][23] and arylation [24][25][26] of

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• been extensively investigated, in the same time little attention has been paid to the corresponding reactions of tetrahydropyridines. During the investigation of the electrochemical oxidation mechanism of tetrahydropyridine 1 [15], an extremely high sensitivity of the formed cation radicals towards

• the formation of the singlet state of 1*, is followed by single-electron transfer from 1* to 3O2 generating 1+• and O2− • in solution. Such reactions between strong nucleophiles and strong electrophiles, especially the annihilation reactions between ion radicals, have not been studied extensively

• , probably due to the difficulties of generating anion and cation radicals simultaneously [24][25]. The reactivity of superoxide is widely studied by chemists and biochemists. It has been shown electrochemically that O2− • is a product of the reversible one-electron reduction of dioxygen in aprotic solvents

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides

• Svetlana F. Malysheva,
• Alexander V. Artem’ev,
• Nina K. Gusarova,
• Nataliya A. Belogorlova,
• Alexander I. Albanov,
• C. W. Liu and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 1985–1990, doi:10.3762/bjoc.11.214

• understand the reaction mechanism. Taking these data into account, the following mechanism is suggested (Scheme 3). The first step is assumed to be the generation of phosphinoyl (A) and hydroperoxyl (HOO•) radicals by the reaction of O2 with phosphine oxide 1. Earlier, the transfer of a hydrogen atom from

• )] of the model radicals B and C (with R, R' = Me) reveals that the latter is energetically less preferred than the former, their energy difference is too small (4.38 kcal/mol) to completely prohibit the B→C transformation. Conclusion In summary, we have disclosed an aerobic addition of secondary

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

• Cesar Garcias-Morales,
• David Ortegón-Reyna and
• Armando Ariza-Castolo

Beilstein J. Org. Chem. 2015, 11, 1973–1984, doi:10.3762/bjoc.11.213

• carbanions [13][14], carbocations [15][16][17][18], and free radicals [19][20][21] which has been explained by negative (nX→σ*C–Y) or positive hyperconjugation (σC–Y→π* or p). Hyperconjugation is commonly described as the interaction between electronic orbitals where one filled orbital (donor) interacts with

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

• Ya Lin Tnay,
• Gim Yean Ang and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

• the construction of oxaspirocyclohexadienones as well as in the electrophilic cyanation of Grignard reagents with pivalonitrile as a CN source. Keywords: C–C bond cleavage; copper; ketimines; molecular oxygen; radical; Introduction Alkylideneaminyl radicals (iminyl radicals) have been utilized for

• the synthesis of azaheterocycles through an intramolecular N–C bond formation with the unsaturated systems [1][2][3][4][5][6]. As precursors of iminyl radicals, readily available oximes and their derivatives have commonly been utilized. The generation of iminyl radicals involves the homolysis of the N

• –O bond with radical initiators [7][8][9][10][11][12][13][14][15] (Scheme 1a) or using thermal [16][17][18][19][20] or photoreaction conditions [21][22][23][24][25][26][27] (Scheme 1b). An alternative route to iminyl radicals is the single-electron reduction of oxime derivatives mediated by the

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• protonation of the Sm(III) alcoholate by the second indole equivalent. We did not observe addition of the intermediate oxycarbonyl radicals to the 2- or 3-position of the unsubstituted indole, which could have occurred as intermolecular reaction. This is in accordance with results by Reissig et al. who

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• ; radical cyclization; radical fragmentation; spiro-indoles; Introduction Radical additions and cyclizations of ene-sulfonamides are useful reactions in a number of settings. The primary products of these reactions, α-sulfonamidoyl radicals, are often thought to undergo elimination reactions of sulfonyl

• radicals to make transient imines [1][2][3]. In turn, onward reactions of the imines provide assorted products including ketones and nitrogen heterocycles [4][5][6][7][8][9][10]. Figure 1a shows a generic addition/elimination reaction of ene-sulfonamides along with example transformations in Figure 1b from

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• cation radicals Molecular conductors derived from CT complexes and radical salts of TTFs are widely known [1], and mixed-valence (TTF2)n+ (0 < n < 1) was reported to form self-accembled conducting nanofibers (σrt = ~10−2 S cm−1) [78][79][80][81][82]. However, there is only a limited number of examples of

• = 3.1 × 10-5 S cm−1) depending on their stacking structures. Cation radicals of pyrrole-fused TTF trimer 38 also formed conducting nanostructures when a CH2Cl2 solution of 381.5(•+) was mixed with an excess amount of hexane. The XRD pattern of the fiber 381.5(•+) is composed of a lamellar structure

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

• appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with

• , cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions

• included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas. Keywords: carboxylic acids; free radicals

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

• 10.3762/bjoc.11.162 Abstract Pyridine promotes dediazoniation of aryldiazonium tetrafluoroborates. The formed aryl radicals were trapped with B2pin2, iodine, or tetrahydrofuran to afford boronic esters, iodobenzenes and benzenes, respectively. The application to the synthesis of (pentafluorosulfanyl

• for an efficient reaction. Alkali metal acetates are known to facilitate decomposition of aryldiazonium salts by the formation of diazoacetates and diazo anhydrides, which decompose to aryl radicals [76]. These additives were used in Meerwein arylation of isopropenyl acetate [77]. In our case, two

• tetrafluoroborates and suggested the formation of diazopyridinium salts which homolytically decompose to aryl radicals, nitrogen and a pyridinium tetrafluoroborate radical [79][80]. Tanaka and co-workers have used the combination of PhN2+BF4− and pyridine for arylations of silylenol ethers [81]. They have observed

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow Region, 141700, Russian Federation 10.3762/bjoc.11.151 Abstract This study compares the ability to scavenge different peroxyl radicals and to act as chain-breaking antioxidants of monomers related to curcumin (1): dehydrozingerone (2

• reactions of the antioxidants with peroxyl radicals; model 2 – lipid autoxidation (lipidAO) used for assessing the chain-breaking antioxidant efficiency and reactivity; model 3 – oxygen radical absorbance capacity (ORAC), which yields the activity against peroxyl radicals generated by an azoinitiator; model

• natural ones as potential pharmaceutical and food ingredients. The present study compares the capacity of curcumin-related compounds to scavenge different free radicals and to act as chain-breaking antioxidants. Curcumin is one of the best natural antioxidants with a wide spectrum of biological activities

Intermolecular addition reactions of N-alkyl-N-chlorosulfonamides to unsaturated compounds

• Gerold Heuger and
• Richard Göttlich

Beilstein J. Org. Chem. 2015, 11, 1226–1234, doi:10.3762/bjoc.11.136

• catalysis and amidyl radicals, a concerted mechanism has been ruled out and a polar mechanism via chloronium ions would lead to the opposite regiochemistry. Keywords: addition reactions; catalysis; N-chlorosulfonamides; haloamination; radical reaction; Introduction In earlier publications we described the

• cyclisation of various unsaturated N-hetero-substituted amines and amides via radicals [1][2][3] and other mechanistic pathways [4][5][6][7][8]. Although reported by other groups [9][10][11] in our hands an efficient intermolecular addition reaction of N-hetero substituted amines via radicals was not possible

• in appreciable yields. The reactivity of the intermediate aminyl radicals towards alkenes was simply not high enough and various side reactions became predominant. We therefore turned our attention to more electrophilic, thus more reactive, nitrogen-centered radicals and chose sulfonamidyl radicals

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• increase of the oxidant concentration generates more free-hydroxyl radicals, causing the dye decolorization. On the contrary, a slight decrease of the decolorization process from 84% to 79% has occurred for a highest amount of H2O2 (0.7 mL) because the solution undergoes self-quenching (scavenger) of OH

• · radicals by adding amounts of H2O2 to produce HO2· radicals, according to the following equations: H2O2 + HO· → H2O + HO2· HO2·+ HO· → H2O2 + O2 We observe that all curves depicted in Figure 7 have a pseudo-first-order kinetics shape, suggesting, therefore, a first-order kinetics law. Effect of the initial

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• ]+ mixed-valence dimer [47][48] and the absorption bands centered around 600 nm to the (TTF˙+)2 π-dimer [49]. The band close to 825 nm could be assigned to cation radicals stack with self-assembly affording mixed-valence. Nevertheless, at this stage, it would be premature to conclude with certainty. The

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• cation radicals. In contrast, TTF units separated by TEE-bridges in acyclic arrangements, either linearly conjugated or cross-conjugated, behaved as independent redox centres and the intermediate singly-charged gem-TEE species did not exhibit IVCT bands. With simple ethynediyl or butadiynediyl spacers in

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

• 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

• the radicals formed on the PEG network. The amount of radicals formed on the PEG chain is not affected by the presence of CA, but rather by the benzophenone concentration which was kept constant so far. Therefore, we varied the benzophenone concentration from 60 mmol/L to 420 mmol/L. From the results

• concentration, confirming that benzophenone concentration affects the formation of surface radicals, which also suggests a grafting from mechanism for CA. The benzophenone concentration has an effect on the CA functionalization degree but the tunable range is still narrow. Therefore, we varied the irradiation

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• lanthanide metal. The authors were able to achieve the asymmetric 1,4-addition of dibenzyl malonate in good yields and enantioselectivies under these conditions (Scheme 27). Lewis acid catalysts have also been used to promote asymmetric 1,4-addition of radicals to α,β-unsaturated amides. Though there were a

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• gem-dimethyl effect. In the case of the spiro products, an exception is the spirocycle 23 derived from cinnamyl bromide reaction with the intermediate 29 (see Scheme 8). At the O-cinnamyl stage, the formation of two highly stabilised radicals could provide a driving force for a 1,3-shift leading to