Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

•  43e) [127]. At present, only a limited number of reports are available for electrocatalytic CDC reactions involving ether α-C(sp3)–H bonds and their susceptibility to electrocatalytic conditions, which hinders the application of electrocatalysis in this type of coupling reaction [128][129][130

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• . Further, we demonstrated that diazidation could be rendered catalytic using Fe(III) nitrate hydrate III as the iron source and performing the reaction under continuous flow conditions. Interestingly, this mechanism bears some similarity to Lin’s electrocatalytic diazidation, where azido radical generation

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• electrocatalytic efficiency (TON up to 2000) was achieved using the TEMPO derivative non-covalently immobilized on the surface of a carbon cloth anode due to the π–π stacking interaction between the pyrene fragment of the catalyst and the electrode surface [103] (Scheme 15). However, this method is not compatible

• intermediate is depicted in Scheme 28). Quinone derivatives could also be generated in situ by anodic oxidation of phenolic compounds. An example of such process is the electrocatalytic biomimetic synthesis of secondary amines by o-azaquinone catalysis [130] (Scheme 29). Under anodic oxidation conditions imine

• electrochemical oxidation of primary alcohols and aldehydes to carboxylic acids. Electrocatalytic oxidation of benzylic alcohols by a TEMPO derivative immobilized on a graphite anode by π–π stacking interactions. Electrochemical oxidation of carbamates of cyclic amines to lactams and oxidative cyanation of amines

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• often employed. Médebielle et al. successfully carried out the cathodic reduction of ArCF2X and RCOCF2X with nitrobenzene as a mediator to generate the corresponding difluoromethyl radicals selectively, and they applied this electrocatalytic system to the synthesis of various heterocyclic compounds

• reduction of 1 using o-phthalonitrile as mediator At first, cyclic voltammetry was carried out to investigate the electrocatalytic reduction of bromodifluoromethyl phenyl sulfide (1) with o-phthalonitrile as a mediator. The cyclic voltammograms of o-phthalonitrile in the absence and presence of compound 1

• peak current disappeared completely as shown in Figure 1c. The reduction peak potential of 1 is −2.4 V vs. SSCE, which excludes the reduction of 1 at this potential. Therefore, the enhanced cathodic current of o-phthalonitrile clearly suggests that a typical electrocatalytic reduction reaction takes

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• is not new, but has become one of the most important topics being discussed today. Due to the energy of hydrogen–hydrogen bonding, water electrolysis enables chemical storage of renewable electricity. Chatenet, Carrey and co-workers showed that the electrocatalytic reaction of hydrogen formation from

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• was used. Both 3a and 4 are products obtained through the reduction of imine 1, which suggests that the GC cathode is effective for the reduction of imine 1. In sharp contrast, the yields of both 3a and 4 were very low when a Ag cathode was used. A Ag cathode has electrocatalytic activity for the

Electrocatalytic C(sp³)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

• Bin Guo and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

• Bin Guo Hai-Chao Xu Key Laboratory of Chemical Biology of Fujian Province and College of Chemistry and Chemical Engineering, Xiamen University, People’s Republic of China 10.3762/bjoc.17.178 Abstract Electrocatalytic dehydrogenative C(sp3)–H/C(sp)–H cross-coupling of tetrahydroisoquinolines with

• electrocatalytic dehydrogenative cross-coupling reaction of tetrahydroisoquinolines with terminal alkynes in continuous flow (Scheme 1D). These reactions require low loadings of supporting electrolyte and proceed through Cu/TEMPO relay catalysis without need for additional ligands. Results and Discussion The

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

• asymmetric electrocatalytic reactions. Review Classification and systematic description of chiral inductors Transformations of achiral organic substrates into chiral products by electrochemical synthetic methods require the active participation of an external source of chirality. Organic chemists working in

• electrocatalytic hydrogenation of α-keto esters 12 to afford corresponding hydroxy esters 13b and 13c with appreciable enantioselectivities (Scheme 6). Following the pioneering works by Grimshaw et al. [28] in 1973, Gileadi and co-workers showed that the addition of quinidine or related alkaloids to the reaction

• for the electrocatalytic oxidative coupling of 42 using constant potential electrolysis of the substrates on a graphite felt electrode modified with TEMPO in the presence of (−)-sparteine 43. The electrolysis resulted in (S)-binaphthyl type dimers 44 with excellent yield and enantiomeric excess

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• not been reported in the literature, with the exception of electrocatalytic systems [26][27]. To achieve functional simulations of B12 enzymes under non-enzymatic conditions, our strategy is to fabricate the artificial enzymes by combining a functional equivalent of B12 and that of an apoenzyme

Bioinspired cobalt cubanes with tunable redox potentials for photocatalytic water oxidation and CO₂ reduction

• Zhishan Luo,
• Yidong Hou,
• Jinshui Zhang,
• Sibo Wang and
• Xinchen Wang

Beilstein J. Org. Chem. 2018, 14, 2331–2339, doi:10.3762/bjoc.14.208

• ample choice of organic ligand architectures to tailor the electronic properties of the “Co4O4” unit for catalysis. In this regard, Nocera et al. selected an organic ligand bearing an electron-withdrawing group (fluorine) to optimize the “Co4O4” cubane unit for electrocatalytic water oxidation [52]. As

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

• electrocatalytic HMF oxidation. However, using a Pt electrode at pH 10, only sluggish FDCA formation in trace amounts was achieved (below 1%) [26]. This result highlights the need for highly efficient catalysts to enhance the oxidation of HMF to FDCA at high pH values. Li and co-workers studied the electrochemical

• Te), could likewise lead to an enhanced electrocatalysis for reactions other than the OER and the HER. To this end, alloys of cobalt with boron, silicon, phosphorus, arsenic and tellurium were screened for their electrocatalytic activity for HMF oxidation. A detailed synthetic procedure to afford

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

• control of selectivity. Moreover, additional parameters such as pH value, the nature of the ions and the concentration of glycerol in the liquid phase can be tuned in liquid-phase processes [4]. Monitoring of electrocatalytic reactions is challenging as all products are dissolved in the electrolyte. High

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• )-azobenzenes can be prolonged dramatically by ortho-fluorine substitution, resulting in half-lives of up to two years at room temperature [19]. These highly thermally stable (Z)-ortho-fluoroazobenzenes can be re-isomerized almost instantaneously in an electrocatalytic fashion [20]. Furthermore, (Z)-azobenzenes

Investigating radical cation chain processes in the electrocatalytic Diels–Alder reaction

• Yasushi Imada,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 642–647, doi:10.3762/bjoc.14.51

• , the turnover number, also referred to as catalytic efficiency, remains unclear in most cases. Herein, we disclose our investigations of radical cation chain processes in the electrocatalytic Diels–Alder reaction, leading to a scalable synthesis. A gram-scale synthesis was achieved with high current

• efficiency of up to 8000%. The reaction monitoring profiles showed sigmoidal curves with induction periods, suggesting the involvement of intermediate(s) in the rate determining step. Keywords: chain process; Diels–Alder reaction; electrocatalytic; radical cation; single electron transfer; Introduction

• ], some of which were achieved with a catalytic amount of electricity. Such electrocatalytic cycloadditions should involve radical cation chain processes, meaning that the reaction is not only triggered by an oxidative SET at the surface of the electrode but also by an intermolecular SET process in bulk

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone

• Cristina Mozo Mulero,
• Alfonso Sáez,
• Jesús Iniesta and
• Vicente Montiel

Beilstein J. Org. Chem. 2018, 14, 537–546, doi:10.3762/bjoc.14.40

• Cristina Mozo Mulero Alfonso Saez Jesus Iniesta Vicente Montiel Instituto de Electroquímica, Universidad de Alicante, Apartado 99, 03080 Alicante, Spain 10.3762/bjoc.14.40 Abstract The electrocatalytic hydrogenation of benzophenone was performed at room temperature and atmospheric pressure using

• analysis (TGA). Cathodes were prepared using Pd electrocatalytic loadings (LPd) of 0.2 and 0.02 mg cm−2. The anode consisted of hydrogen gas diffusion for the electrooxidation of hydrogen gas, and a 117 Nafion exchange membrane acted as a cationic polymer electrolyte membrane. Benzophenone solution was

• synthesis of diphenylmethanol upon the lowest current density. With regards to an increase by ten times the Pd electrocatalytic loading the electrocatalytic hydrogenation led neither to an increase in fractional conversion nor to a change in selectivity. Keywords: benzophenone; diphenylmethanol

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• Business University, Beijing 100048, China 10.3762/bjoc.14.35 Abstract An efficient electrocatalytic functionalization of N-arylglycine esters is reported. The protocol proceeds in an undivided cell under constant current conditions employing the simple, cheap and readily available n-Bu4NI as the mediator

• catalyst, the yield of 3aa increased to 81% (Table 1, entries 16–19). On the basis of the screening of reaction conditions, we could conclude that the electrocatalytic oxidative coupling should be performed in a mixed solution of CH3CN and CH2Cl2 (v/v = 1:2), in the presence of n-Bu4NI (30 mol %) as the

• 36% and 27% yields, respectively. However, 3ga and 3ha were isolated in 14% and 11% yields, respectively, under the direct electrolytic conditions. In the cases of N-arylglycine methyl ester 1i and N-arylglycine benzyl ester 1j, the electrocatalytic functionalization afforded excellent yields of 3ia

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

• [31]. Nevertheless, the applied Ni electrodes usually exhibit a high stability against corrosion at these conditions due to the formation of an electrocatalytic surface layer which is stable in alkaline electrolytes [32]. Kraft pulping represents the predominant pulping process [33]. Due to this we

• during lignin oxidation [34]. The chemical relation between Ni and Co implies a similar electrocatalytic behaviour. The major focus of this study was to investigate the applicability of a lignin degradation process under technically relevant conditions. This implies an aqueous system due to the limited

• solubility of Kraft lignin as well as temperatures below 100 °C to avoid pressurized systems. Several electrode materials, based on Ni or Co alloys, were investigated towards their electrocatalytic activity in this particular degradation process. Table 1 displays yields of 1 by electrochemical degradation

IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf₂N ionic liquid

• Andrea P. Sandoval,
• Marco F. Suárez-Herrera and
• Juan M. Feliu

Beilstein J. Org. Chem. 2015, 11, 348–357, doi:10.3762/bjoc.11.40

• electrochemical properties, as the ionic resistance or the electrocatalytic activity, of PEDOT are affected by the surface energy state of the electrode [6]. For example, it was found that the ionic resistance of the PEDOT films electrochemically synthesized on platinum electrodes increases in the order Pt(100

• ) during the first cycles. Figure 1 clearly shows that the electrochemical polymerization of EDOT on platinum electrodes is a surface sensitive reaction. It was found that Pt(111) has the highest electrocatalytic activity for the EDOT oxidation reaction followed by Pt(110) and finally Pt(100). Taking into

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• prepared using cyanides. In the proposed setup for the electrocatalytic preparation of MHA, a boron-doped diamond coated permeable cathode and Pt coated permeable anode rest directly on the cation exchange membrane to decrease ohmic resistance by the membrane, minimizing the required voltage. Hydrogen

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

• perfluoroalkylcarboxylate, which extrudes CO2 to yield the desired product (Table 9). As underlined by the authors, the electrocatalytic reactions proceed under mild conditions at potentials that clearly generate high oxidation state metals. 3.1.4 Trifluoromethylation by means of presumed C–H activation and a nucleophilic

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

• Alicja Schlange,
• Antonio Rodolfo dos Santos,
• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2011, 7, 1412–1420, doi:10.3762/bjoc.7.165

• method a significantly higher electrocatalytic activity was reached, which can be attributed to the higher metal loading and smaller and more uniformly distributed Pt particles on the carbon support. Our approach introduces a simple, time-saving and cost-efficient method for fuel cell catalyst

• electrochemical activity, resulting in higher power density values. It is known that the catalyst preparation method strongly influences the noble metal cluster size and its dispersion on the carbon and therefore the electrocatalytic activity [19]. DMFC electrocatalysts are mostly prepared in batch processes

• average cluster size resulting in lower electrocatalytic activity, as reported by [21]. The microemulsion method allows for better control of the nanoparticle size and distribution in comparison to the impregnation method. Disadvantages of this method are the high cost of the used surfactants and their