Search results

Search for "oxidants" in Full Text gives 216 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

  • Marek Kõllo,
  • Marje Kasari,
  • Villu Kasari,
  • Tõnis Pehk,
  • Ivar Järving,
  • Margus Lopp,
  • Arvi Jõers and
  • Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

Graphical Abstract
  • toxic oxidants. Keywords: chemoenzymatic synthesis; cortisol; hydroxylation; secosterol; whole-cell catalysis; Introduction Developments in the chemistry of steroids have stimulated extensive research interest in the exploration of new synthetic methods since the 1960s. Advances in synthetic biology
  • synthetic methods for secosteroids is wide. However, usually these are multistep sequences exploiting toxic oxidants. Marine invertebrates are a rich source of oxidated and highly functionalized steroidal metabolites, including secosteroids. Since the first isolation of 9,11-secosterol from
  • ideal starting compound for this synthesis. Chemical oxidation methods for the synthesis of steroids often require stoichiometric amounts of toxic reagents, and the selectivity of the oxidation is still an unsolved problem [21]. Typically, toxic oxidants, such as OsO4, SeO2 and Pb(OAc)4 are used in this
PDF
Album
Supp Info
Full Research Paper
Published 01 Mar 2021

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

  • Lucía Rossi-Fernández,
  • Viviana Dorn and
  • Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

Graphical Abstract
  • been reported, efficient and selective epoxidation of olefins remains a challenge. Due to safety and environmental issues, traditional methods involving the use of stoichiometric amounts of harmful oxidants (for example, peroxosulfates [13] or organic peracids [14]) have been replaced by the use of
  • greener oxidizing agents as molecular oxygen, hydrogen peroxide or tert-butyl hydroperoxide (TBHP) [14][15][16][17]. However, using any of these oxidants alone results in considerable low reactivity and selectivity in olefin epoxidation reactions. Thus, several transition-metal-based catalytic methods
  • the oxidant agent. Among the reported methods that make use of peroxides as oxidants, cobalt nanoparticles supported on CNTs together with TBHP as oxidant for the epoxidation of styrene, gave good selectivity to styrene oxide but conversions were lower than 40% [41]. More recently, Hutchings et al
PDF
Album
Supp Info
Full Research Paper
Published 22 Feb 2021

The preparation and properties of 1,1-difluorocyclopropane derivatives

  • Kymbat S. Adekenova,
  • Peter B. Wyatt and
  • Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

Graphical Abstract
  • and the subsequent aerobic oxidation by an amine. Single-electron oxidants such as cerium ammonium nitrate or K2S2O8 were used for the regiospecific ring opening of the simple gem-difluorocyclopropanes 134 (Scheme 58). The brominative ring-opening reactions of compounds 134 gave good yields of the
PDF
Album
Review
Published 26 Jan 2021

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

  • Takashi Yamazaki,
  • Yoh Nakajima,
  • Minato Iida and
  • Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

Graphical Abstract
  • already reported procedure [4][19] as well as by the ones developed by other groups [22][23]. In spite of the previous unfavorable results for the oxidative transformation of 1a by MnO2 as well as other oxidants [18][23], MnO2 was selected due to the low cost and convenient handling. After a number of
PDF
Album
Supp Info
Full Research Paper
Published 15 Jan 2021

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

  • Mysore Bhyrappa Harisha,
  • Pandi Dhanalakshmi,
  • Rajendran Suresh,
  • Raju Ranjith Kumar and
  • Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

Graphical Abstract
  • thiocyanate 2 in the presence of several oxidants and metal salts (Table 1). The initial attempts employing iodine, CAN and ZnCl2 upon refluxing in acetonitrile for 6 hours did not yield any product (Table 1, entries 1, 2 and 4). When potassium persulfate (K2S2O8) is employed, highly substituted oxazole 3i
PDF
Album
Supp Info
Full Research Paper
Published 31 Aug 2020

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

  • Sharna-kay Daley and
  • Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

Graphical Abstract
  • establish high-yielding and selective oxidative coupling reactions, has afforded new and greener synthetic protocols for biaryls [5][6][7]. Several oxidants, such as the salts of Ag(I&II) [8], Ti(III&IV) [9], Mn(III) [10], Ce(IV) [11], Sn(IV) [12] and Fe(III) [13], as well as the hypervalent iodine reagents
  • phenyliodine diacetate (PIDA) and phenyliodine bis(trifluoroacetate) (PIFA), have been utilized for oxidative dimerization reactions [14][15]. The use of these one-electron oxidants, as well as non-metallic reagents, plays an important role in accessing symmetrical and asymmetrical biaryls and polyaryls [1
  • ), was subjected to the oxidants activated carbon (Act-C), potassium ferricyanide (K3[Fe(CN)6]), p-benzoquinone and stannic chloride (SnCl4). As shown in Scheme 4, with the exception of SnCl4, all oxidants resulted in the re-oxidation of the hydroxylated substrate to naphthoquinone 7. SnCl4, however
PDF
Album
Supp Info
Full Research Paper
Published 18 Aug 2020

Syntheses of spliceostatins and thailanstatins: a review

  • William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

Graphical Abstract
  • ) gave the C-phenyl glucoside 75 [36]. Notably, the use of oxidants other than BQ gave either the TMS enol ether or the 2,3-dihydro-6-phenyl-4H-pyran-4-one. The C-3 exocyclic methylene group was introduced by a Wittig olefination, and after the manipulation of the protecting groups, a VO(acac)2-catalyzed
PDF
Album
Review
Published 13 Aug 2020

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K2S2O8

  • Qiang Liu,
  • Weibang Lu,
  • Guanqun Xie and
  • Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

Graphical Abstract
  • better product yields as compared with the reactions performed at either 70 °C or 90 °C (Table 1, entries 2, 16, and 17). Then, various oxidants such as (NH4)2S2O8, Na2S2O8, TBHP (tert-butyl hydroperoxide), DTBP (di-tert-butyl peroxide), and dioxygen were tested and the results showed that K2S2O8
PDF
Album
Supp Info
Letter
Published 12 Aug 2020

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

  • Lucas Guillemard and
  • Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

Graphical Abstract
  • concerned the development of “classical” C–H activation reactions, while a photoredox cycle was implemented to reoxidize the metal catalyst, thus obviating the need for a stoichiometric amount of metal-based oxidants, such as silver or copper salts. In parallel, dual synergistic catalysis has emerged. In
  • activation, a catalytic amount of a transition metal (generally Pd, Rh and Ru) is frequently used in combination with a stoichiometric amount of an external oxidant (typically Cu or Ag salts). Such additional oxidants are required if transiently produced low-valent metal complexes need to be reoxidized by
  • selecting judiciously a PC with adequate redox potentials, the ground state of the latter could be regenerated by means of a mild and abundant oxidant such as molecular oxygen. The overall process thus allowed the replacement of stoichiometric amounts of external oxidants with a suitable PC. Following this
PDF
Album
Review
Published 21 Jul 2020

Pauson–Khand reaction of fluorinated compounds

  • Jorge Escorihuela,
  • Daniel M. Sedgwick,
  • Alberto Llobat,
  • Mercedes Medio-Simón,
  • Pablo Barrio and
  • Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

Graphical Abstract
  • , mild oxidizing additives such as amine oxides, aminophosphines, phosphine oxides, and sulfoxides may be used as promoters to facilitate the dissociation step, by oxidatively removing one of the CO ligands in form of CO2 [40]. The most common oxidants are N-morpholine N-oxide (NMO), trimethylamine N
PDF
Album
Review
Published 14 Jul 2020

Fluorohydration of alkynes via I(I)/I(III) catalysis

  • Jessica Neufeld,
  • Constantin G. Daniliuc and
  • Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

Graphical Abstract
  • fluorinating reagents [44][45]. Developments by Hammond and Xu validated N-pyridine oxides as terminal oxidants to substitute Selectfluor® for the cationic Au(I)/Au(III) cycle, thereby enabling high functional group tolerance [46][47][48][49]. Inspired by these and other selected advances [50][51], in metal
  • toluene proved to be detrimental (19% and 10%, respectively, Table 1, entries 7 and 8). A screen of common oxidants for I(I)/I(III) catalysis confirmed Selectfluor® as being ideally suited, in line with our previous observations [26][27][28][29][30]. Whereas m-CPBA generated the desired α-fluoroketone 2
PDF
Album
Supp Info
Full Research Paper
Published 10 Jul 2020

Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells

  • Giacomo Mari,
  • Lucia De Crescentini,
  • Serena Benedetti,
  • Francesco Palma,
  • Stefania Santeusanio and
  • Fabio Mantellini

Beilstein J. Org. Chem. 2020, 16, 1606–1616, doi:10.3762/bjoc.16.133

Graphical Abstract
  • , namely pyrrolino-tetrahydroberberines, synthesized by some of us [68], exhibited enhanced antioxidant properties in comparison to THBER against a wide variety of pathophysiologically relevant oxidants such as peroxyl radicals, ferrous ion, and hydrogen peroxide [65]. In continuation of our ongoing
PDF
Album
Supp Info
Full Research Paper
Published 06 Jul 2020

Oxime radicals: generation, properties and application in organic synthesis

  • Igor B. Krylov,
  • Stanislav A. Paveliev,
  • Alexander S. Budnikov and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

Graphical Abstract
  • diacetyliminoxyl radical [44], 1595 сm−1 for the di(1-adamantyl)iminoxyl, and 1610 сm−1 for the di-tert-butyliminoxyl radical [45]). Various oxidants were used for the generation of iminoxyl radicals from oximes, including transition metal compounds, such as (NH4)2Ce(NO3)6 [38][46], Fe(ClO4)3 [44][46], Cu(ClO4)2
  • [46], Pb(OAc)4 [44][46][47][48][49][50][51], PbO2 [52], Mn(OAc)3 [46], KMnO4 [46], Ag2O [53], AgO [54], Horseradish peroxidase/H2O2 [55], metal-free oxidants PhI(OAc)2 [46], t-BuOOt-Bu [53] or quinones [56] under UV irradiation. Anodic oxidation was also reported [57]. The establishing of the self
  • the oxime group. The lowest yield was obtained with an aromatic oxime (product 46e, yield 27%). Later, the Cu(BF4)2 (cat.)/t-BuOOH oxidative system [87] was proposed as an alternative to stoichiometric metal-containing oxidants, such as KMnO4, Mn(OAc)3, and KMnO4/Mn(OAc)3 (Scheme 16). 1,3-Ketoesters
PDF
Album
Review
Published 05 Jun 2020

Activated carbon as catalyst support: precursors, preparation, modification and characterization

  • Melanie Iwanow,
  • Tobias Gärtner,
  • Volker Sieber and
  • Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

Graphical Abstract
  • of oxygen-containing surface groups can be influenced by treatment with different oxidants such as H2O2, HNO3, oxygen/ air, ozone or NaOCl. Thereby, the acidic or basic behavior and the resulting surface chemistry of the activated carbons are determined. Jaramillo et al. investigated the influence of
PDF
Album
Review
Published 02 Jun 2020

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

Graphical Abstract
  • transformation, the arene is first oxidized by the excited state of the photocatalyst, generating the arene radical cation I. The latter then undergoes a nucleophilic attack of the N-heterocycle, affording the radical adduct II. TEMPO and O2 act as oxidants for the formation of the final aromatic compound via
  • 4ClCzIPN (OD8), obtained through fine-tuning of 4CzIPN (OD6), which are both strong oxidants and reductants [144]. In the search for a more atom-economical approach, the group of Li developed an iminyl radical formation by the N−H bond cleavage from the diarylimines 29.1 (Scheme 29) [145]. The direct
  • used as initators for the synthesis of highly functionalized benzo[b]phosphole oxides from arylphosphine oxide and alkynes [162]. Alkyl hydroperoxides can act as oxidants in photocatalytic cycles, furnishing the desired alkoxy radicals. Several organic dyes have been exploited in these processes
PDF
Album
Review
Published 29 May 2020

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

  • Rodrigo Costa e Silva,
  • Luely Oliveira da Silva,
  • Aloisio de Andrade Bartolomeu,
  • Timothy John Brocksom and
  • Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

Graphical Abstract
  • involves energy transfer to surrounding molecules, such as molecular oxygen, heterocycles and other relevant molecules [15][16][17]. The excited states of porphyrins are also both potent oxidants and reductants when compared to the ground state. This phenomenon can be measured by the comparison of the
PDF
Album
Review
Published 06 May 2020

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

  • Liliia Moshniaha,
  • Marika Żyła-Karwowska,
  • Joanna Cybińska,
  • Piotr J. Chmielewski,
  • Ludovic Favereau and
  • Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

Graphical Abstract
  • obtained by tandem cyclodehydrogenations of oligoaryl precursors [1][2][3]. This general strategy is attractive because it does not require prefunctionalization of coupling sites and because it provides rapid access to complex π systems. Such cyclodehydrogenations can be performed using diverse oxidants [4
PDF
Album
Supp Info
Full Research Paper
Published 04 May 2020

Cascade trifluoromethylthiolation and cyclization of N-[(3-aryl)propioloyl]indoles

  • Ming-Xi Bi,
  • Shuai Liu,
  • Yangen Huang,
  • Xiu-Hua Xu and
  • Feng-Ling Qing

Beilstein J. Org. Chem. 2020, 16, 657–662, doi:10.3762/bjoc.16.62

Graphical Abstract
  • knowledge, the combination of bis(trifluoromethylthiolation) [36][39][40][41] and cascade cyclization reactions has not been reported before. Thus, the amounts of AgSCF3 and K2S2O8 were increased to deliver 2a in 52% yield (Table 1, entry 2). Other oxidants including Na2S2O8 and (NH4)2S2O8 afforded 2a in
PDF
Album
Supp Info
Letter
Published 08 Apr 2020

Room-temperature Pd/Ag direct arylation enabled by a radical pathway

  • Amy L. Mayhugh and
  • Christine K. Luscombe

Beilstein J. Org. Chem. 2020, 16, 384–390, doi:10.3762/bjoc.16.36

Graphical Abstract
  • ]. While many direct arylation systems occur under neutral conditions and without the need for strong oxidants or reductants, only few proceed at ambient temperatures [3][6]. To our knowledge, only one example of room-temperature DArP exists, namely polymerizing poly-3-hexylthiophene to an acceptably high
PDF
Album
Supp Info
Full Research Paper
Published 13 Mar 2020

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

  • Rafia Siddiqui and
  • Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

Graphical Abstract
  • dependence on external oxidants and harsh reaction conditions [83][84]. In this context, in 2014, Fabry et al. reported the use of novel dual photoredox catalytic systems made up of photoredox catalyst 11 and a rhodium catalyst to carry out the Weinreb amide C–H olefination shown in Scheme 1 [85]. By using
  • out without the requirement of a proton acceptor or external oxidant, and hydrogen gas was obtained as the only side product (Scheme 6). This was a major achievement since the previously reported methods suffered from undesirable side products and the requirement of oxidants [102][103]. After the use
  • oxidants [151][152][153]. To overcome these drawbacks, recently, Cho’s group synthesized carbazole derivatives using a dual photoredox-catalyzed intramolecular C−H bond amination of N-substituted 2-amidobiaryls with photoredox catalyst 14 in presence of Pd(OAc)2 as a cocatalyst under aerobic conditions
PDF
Album
Review
Published 26 Feb 2020

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

  • Abhijit Paul,
  • Debnath Chatterjee,
  • Srirupa Banerjee and
  • Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

Graphical Abstract
  • -withdrawing groups, using Pd(OAc)2 as catalyst and Cu(OAc)2 as oxidant [25]. Since then, several variants of the reaction involving Pd catalysis and various oxidants have been reported for the synthesis of 3-alkenylindoles. For example, Chen et al. and Huang et al. independently reported the C3 alkenylation
  • carried out employing indole (1a), methyl acrylate (2a), and 3 mg of the RuNC. Different oxidants as well as solvents were explored for the reaction. From the optimisation reactions and the control experiments, it was concluded that the reaction with Cu(OAc)2 as the oxidant in DMF/DMSO, 9:1, v/v at 130 °C
PDF
Album
Supp Info
Full Research Paper
Published 29 Jan 2020

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

  • Qiao Li,
  • Chen Zhuang,
  • Donghua Wang,
  • Wei Zhang,
  • Rongxuan Jia,
  • Fengxia Sun,
  • Yilin Zhang and
  • Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

Graphical Abstract
  • reagents have emerged as a class of efficient and environmentally benign nonmetal “green” oxidants [66][67][68][69][70][71][72][73]. For instance, iodosobenzene (PhIO) [74] has been widely used in many synthetic transformations. It was found that PhIO is efficient in realizing epoxidation of olefins [75
  • generation of some unidentified byproducts. A solvent screening identified DMF to be the most appropriate solvent for this transformation (Table 1, entries 1–9). Other commonly employed oxidants, including phenyliodine(III) diacetate (PIDA), phenyliodine(III) bis(trifluoroacetate) (PIFA), and iodylbenzene
PDF
Album
Supp Info
Letter
Published 12 Dec 2019

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

  • Andreas Boelke,
  • Yulia A. Vlasenko,
  • Mekhman S. Yusubov,
  • Boris J. Nachtsheim and
  • Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

Graphical Abstract
  • stability with reactivity in a model oxygenation. Keywords: differential scanning calorimetry; hypervalent iodine; N-heterocycle; stability; thermogravimetry; Introduction Hypervalent iodine compounds, in particular aryl-λ3-iodanes, have found wide spread applications as oxidants and electrophilic group
  • explosive properties of Togni’s reagent and very recently, Williams and co-workers analyzed the sensitivity of common oxidants including 2-iodoxybenzoic acid (IBX) and Dess–Martin periodinane (DMP) [19][20]. Waser and co-workers examined the thermal stability of the Zhdankin reagent ABX and compared it with
PDF
Album
Supp Info
Full Research Paper
Published 27 Sep 2019

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

  • Xiaowei Li,
  • Xiaolin Shi,
  • Xiangqian Li and
  • Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

Graphical Abstract
  • different oxidation states, tolerance to various guiding groups, easy electroplating of C–H bonds, and the compatibility of many Pd(II) catalysts with oxidants make them act as ideal catalysts for C–H activations [34]. Over the last decade, a number of Pd-catalyzed methods have been developed to synthesize
PDF
Album
Review
Published 23 Sep 2019

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

  • Christoph W. Grathwol,
  • Nathalie Wössner,
  • Sören Swyter,
  • Adam C. Smith,
  • Enrico Tapavicza,
  • Robert K. Hofstetter,
  • Anja Bodtke,
  • Manfred Jung and
  • Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

Graphical Abstract
  • resemble a fixed (Z)-configuration of the stilbene double bond. Therefore, comparison with 2b could provide information concerning differential biological activity of the two photoisomers. By applying Mallory reaction conditions to a solution of 2b in methanol utilizing oxygen and iodine as oxidants we
PDF
Album
Supp Info
Full Research Paper
Published 16 Sep 2019
Other Beilstein-Institut Open Science Activities