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

• for the electrochemical oxidation of lignin [73] and enzymatic oxidations [74][75][76] but have not been widely used in organic synthesis. The di-tert-butyliminoxyl radical proved to be quite unreactive with respect to a C=C double bond containing substrates that are considered as effective scavengers

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• chirally modified electrodes Electrochemical oxidation reactions have long served as substantial synthetic tool because of their ability to increase the functionality of organic molecules via reversing the polarity of electron-rich functional groups and thereby generating highly reactive intermediates

• of 38 to the corresponding sulfoxide 39 with excellent chemical yield although the value of enantiomeric excess was considerably low (Scheme 16) [46]. A few years later, Komori and Nonaka, in two consecutive reports, established a modified method for the asymmetric electrochemical oxidation of alkyl

• -alcohols 63 via electrochemical oxidation in an undivided cell under constant current [61]. This time, they used catalytic amount of a different chiral N-oxyl radical mediator 64 (Scheme 25). The authors proposed that in the biphasic CH2Cl2/water medium, [Br+] is initially generated from [Br−] by

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• range of photochromic families upon the electrochemical oxidation of either their SW or pLW isomers [24]. We have also demonstrated that any modest amount of thermal (or solvatochromic) coloration of the QSHDs is due to small amounts of the electrochromic eLW isomer 5, rather than the photochromic pLW

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

• Jonas Weidner,
• Stefan Barwe,
• Kirill Sliozberg,
• Stefan Piontek,
• Justus Masa,
• Ulf-Peter Apfel and
• Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

• heterogeneous catalysts for the oxidation of HMF. However, the high cost of the noble metal catalysts has aroused interest in transition metal catalysts and alternative methods for the oxidation of HMF. The electrochemical oxidation of HMF to FDCA was first reported in 1991 by Grabowski and co-workers [25

• [4]. The elaborate separation of TEMPO from FDCA appeared to be an additional disadvantage [24]. Recently, Sun and co-workers reported the electrochemical oxidation of HMF using various non-precious cobalt and nickel based bifunctional HER/OER water splitting electrocatalysts, namely CoP on copper

• valuable product is an appealing approach for increasing the competitiveness of the electrochemical hydrogen production. 5-Hydroxymethylfurfural (HMF) is a biomass-derived compound that can be converted to economically more valuable 2,5-furandicarboxylic acid (FDCA) via electrochemical oxidation at a

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• , 44780 Bochum, Germany 10.3762/bjoc.14.120 Abstract The effects of the alkali cations Na+ and K+ were investigated in the alkaline electrochemical oxidation of glycerol over Pd nanoparticles (NPs) deposited on functionalized carbon nanotubes (CNTs). The electrocatalytic activity was assessed by cyclic

• . Conclusion The effects of the alkali cations Na+ and K+ on the electrochemical oxidation of glycerol were investigated over Pd nanoparticles supported on carbon nanotubes. The CNTs used as support for the Pd NPs were either oxygen- or nitrogen-functionalized. Cyclic voltammetry showed that the achieved

Polysubstituted ferrocenes as tunable redox mediators

• Sven D. Waniek,
• Jan Klett,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86

• reactions [29], borylations of arenediazonium salts [30] and in C–H imidation reactions of (hetero)arenes [31] (Scheme 1b,c). Ferrocene has been used as redox mediator for the electrochemical modification of carbon surfaces via electrochemical oxidation of carboxylates [32][33], as mediator for

Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis

• Tatiana Golub and
• James Y. Becker

Beilstein J. Org. Chem. 2018, 14, 861–868, doi:10.3762/bjoc.14.72

• spectrum of products obtained is described in Scheme 8. Except for the expected monomethoxylated II-3a and dimethoxylated II-3b products, fragmentation products (II-3c, 3d, 3e) were observed too. Table 2 below summarizes the type of products and their relative ratios obtained from initial electrochemical

• oxidation of II-3 under various experimental conditions. It appears that the selectivity and efficiency of the anodic process depends on both the anode material and electricity consumption (F/mol). Thus the oxidation of II-3 on a C anode (Table 2, entries 1 and 2) is quite selective providing mostly mono-II

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• electrochemical oxidation was first reported by Tommasino and co-workers in 2002 on three alkenes but yields were below 20% due to the formation of oxidised byproducts [38]. Nicewicz and co-workers in 2013 found suitable reaction conditions for the alkene hydrotrifluoromethylation using CF3SO2Na [39]. The single

• , Smertenko and co-workers described a milder electrochemical trifluoromethylation of a series of aromatic compounds using CF3SO2Na in acetonitrile [56]. Furthermore, the electrochemical oxidation of the trifluoromethylsulfinate anion (from CF3SO2K) generated the trifluoromethyl radical for the reaction of

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• method for obtaining vinylphosphonium salts consists in the one-step electrochemical oxidation of triphenylphosphine in the presence of cycloalkenes. The synthesis of 1-cycloalkenetriphenylphosphonium salts 19 was carried out in the presence of 2,6-lutidine perchlorate and anhydrous potassium carbonate

• aldehydes. Synthesis of 1-cycloalkenetriphenylphosphonium salts by electrochemical oxidation of triphenylphosphine in the presence of cycloalkenes. Suggested mechanism for the electrochemical synthesis of 1-cycloalkenetriphenylphosphonium salts. Generation of α,β-(dialkoxycarbonyl)vinylphosphonium salts by

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• (cyano)(methoxycarbonyl)methanide with episulfides [14] or thioamides [15]. Also, methyl cyanoacetate was reported to undergo both chemical (using (NH4)2Ce(NO3)6 = CAN in methanol) or electrochemical oxidation (Ce(NO3)3, HNO3 in acetonitrile) yielding selectively E-1b in 68 and 77% yield, respectively

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• found to lie in an interval of 60–80%. Electrochemical oxidation of the synthesized chromophores has resulted in the formation of colored thin oligomeric films that became possible due to the presence of carbazole or pyrrole fragments with free electron-rich positions. Keywords: carbazole; chalcone

• ; electrochemical oxidation; pyrimidine; solvatochromism; Introduction Nowadays a great number of research projects concerning the synthesis of organic conjugated systems with a wide scope of their applications, primarily as materials for organic electronic devices such as light-emitting diodes, field-effect

• properties of the prepared compounds were investigated by UV–vis absorption spectroscopy and cyclic voltammetry. Electrochemical oxidation of these heterocycles resulted in the formation of thin films on the surface of an ITO working electrode. The morphology of grown films has been investigated by means of

Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

• Yuta Isoda,
• Norihiko Sasaki,
• Kei Kitamura,
• Shuji Takahashi,
• Sujit Manmode,
• Naoko Takeda-Okuda,
• Jun-ichi Tamura,
• Toshiki Nokami and
• Toshiyuki Itoh

Beilstein J. Org. Chem. 2017, 13, 919–924, doi:10.3762/bjoc.13.93

• electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block. Keywords: automated synthesis; electrochemical oxidation; glycosylation; glucosamine; total synthesis; Introduction

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• energy levels of the polymer films were estimated by square wave voltammetry (SWV, Figure 2) using the oxidation and reduction peak values, respectively. As shown by the square wave voltammograms, the electrochemical oxidation shoulder peaks of PTzBDT-1 and PTzBDT-2 are located at 0.81 V and 0.73 V

Superstructures with cyclodextrins: chemistry and applications III

• Gerhard Wenz and
• Eric Monflier

Beilstein J. Org. Chem. 2016, 12, 937–938, doi:10.3762/bjoc.12.91

• the group of B. J. Ravoo using host–guest interactions between polyethyleneimine grafted with β-CD and a polyamidoamine dendrimer decorated with ferrocene. The formation of the superstructures was reversible by electrochemical oxidation of the ferrocene moieties [6]. Furthermore, significant progress

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• olefins with a tethered amino or oxygen functionality has been achieved for the construction of a variety of 1,2-oxyamino products, using palladium [19][20], platinum [21], gold [22], copper [23][24][25][26], free-radical initiators [27][28][29], hypervalent iodine [30], and electrochemical oxidation [31

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

• oxidizing capacity of the hydroperoxide when its concentration is less or comparable with the tetrahydropyridine leading to another versatile intermediate in organic synthesis – oxaziridine – as the inherent strain of the ring and the relatively weak N–O bond makes it unusually reactive. Electrochemical

• oxidation of 1 in deareated (blue) and O2 saturated (red) solutions of CH2Cl2/0.1 M TBAPF6, c = 5 × 10−4 M. The X-ray structures of compounds 1 and 2. Decrease of the UV absorption band of compound 1 under irradiation (254 nm) in air-saturated CHCl3, c = 5 × 10−5 M. The X-ray structures of compounds 4 and 5

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• electrochemical oxidation of terthiophene 28b (Scheme 13) [72]. The latter was synthesised by the aforementioned synthetic pathway C. The electrochemical method for the preparation of sexithiophene 51 was achieved by potentiostatic oxidative electrodimerization of 28b in a mixture of 2:1 CH2Cl2/hexane, with 0.1 M

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• ligands and the neutral rhenium(I) complex suggests that crystalline radical cation salts can be readily obtained upon chemical and/or electrochemical oxidation. The complexation abililty of the two novel electroactive ligands toward transition metal cations such as Cu(II), Fe(II), Co(II), etc is in

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

• also observed by chemical [6] or electrochemical oxidation (vide infra; also 2b•+ exhibited an IVCT band, with maximum >2000 nm, as previously reported for the related species 2a•+ [10]). By increasing the electrode potential to the value of the second electron transfer (still in the region of the

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

• Longfei Ma,
• Jibin Sun,
• Xiaofeng Lu,
• Shangxi Zhang,
• Hui Qi,
• Lei Liu,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95

• -based conducting materials are mainly produced as radical cation salts by electrochemical oxidation and CT complexes by chemical oxidation with electron acceptors [5][6]. Most Ar-S-TTFs possess redox potentials higher than that of bis(ethylenedithio)-TTF (BEDT-TTF) [33][34][35][36][37][38][39

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• oxidation potential of the mono(trifluoromethyl) derivative 1c (+0.21 V vs Fc+/Fc) prompted us to investigate the formation of cation radical salts upon chemical or electrochemical oxidation of 1c. Indeed, treatment of a solution of 1c with TCNQ afforded black, crystalline elongated plates which were

Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption

• Dominik Schmitt,
• Carolin Regenbrecht,
• Marius Hartmer,
• Florian Stecker and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 473–480, doi:10.3762/bjoc.11.53

• oxidation products like vanillic acid (4). Under these conditions the electrochemical oxidation of vanillin (1) does not take place. This was proven by a control experiment trying to oxidize vanillin (1) in alkaline solution at Ni foam and stainless steel electrodes. In both cases no formation of vanillic

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and

• affords different products depending on the reaction conditions. Keywords: allylic oxidation; cholesterol; electrochemical halogenation; electrochemical oxidation; Introduction Cholesterol is the most common steroid in the mammalian body. It is necessary to ensure a proper membrane permeability and

• these processes, cholesterol has been regarded as an electrochemically inactive compound [14]. However, during the last two decades the electrochemical oxidation of cholesterol, direct and indirect, was studied intensively. The first reports on cholesterol oxidation concerned indirect electrochemical

Functionalized branched EDOT-terthiophene copolymer films by electropolymerization and post-polymerization “click”-reactions

• Miriam Goll,
• Adrian Ruff,
• Erna Muks,
• Felix Goerigk,
• Beatrice Omiecienski,
• Ines Ruff,
• Rafael C. González-Cano,
• Juan T. Lopez Navarrete,
• M. Carmen Ruiz Delgado and
• Sabine Ludwigs

Beilstein J. Org. Chem. 2015, 11, 335–347, doi:10.3762/bjoc.11.39

• /P3T-blend and the copolymer P(EDOT-co-3T)-1:1. During the electrochemical oxidation the homopolymers PEDOT and P3T both show chemically reversible behavior, but they differ significantly in their onset potentials of −0.8 V and 0.3 V vs Fc/Fc+, respectively (blue and red curves). The cyclic

• broad spectral shapes with maxima around 530 nm. From the spectra of the neutral compounds a clear distinction between the copolymer and the blend is not possible. Monitoring the optical properties during the electrochemical oxidation process by in situ spectroelectrochemistry, however, gives further

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• transition state for the oxidation in a manner not possible with a direct electrochemical oxidation. The oxidation proceeded smoothly in the light-driven electrochemical reaction. The yield and ee of the product was in accordance with that reported in the literature for the reaction using a traditional

• oxidize the primary alcohol of a glucose derivative in the presence of the unprotected secondary alcohols. Once again, this is an example of selectivity that cannot be accomplished with a direct electrochemical oxidation, which would select the oxidation based exclusively on potential. Again, the yield

• . The reactions were all easily performed at room temperature and were conducted in simple electrochemical cells and governed by the initial electron-transfer reaction. Given that not all electrochemical oxidation reactions are so straightforward, the compatibility of such a simple photovoltaic power