Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings

• Lifen Peng,
• Ting Wang,
• Zhiwen Yuan,
• Bin Li,
• Zilong Tang,
• Xirong Liu,
• Hui Li,
• Guofang Jiang,
• Chunling Zeng,
• Henry N. C. Wong and
• Xiao-Shui Peng

Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166

• ureas 1 proceeded smoothly in an undivided cell (reticulated vitreous carbon (RVC) anode, Pt cathode, 5 mA), forming the desired indoles 2 in high yields. The reaction showed good compatibility with various functional groups like phenyl, furyl, alkenyl and alkyl at the acetylene moieties, producing 2a–d

• : a mixture of aniline 4 (0.3 mmol), alkyne 3 (0.6 mmol), [RuCl2(p-cymene)]2 (0.03 mmol), KPF6 (0.06 mmol) and NaOAc (0.06 mmol) in H2O/iPrOH (1:1, 6 mL), refluxing under electrolysis (RVC anode, Pt cathode, 10 mA) for 1.8–3.9 h. This reaction was compatible with anilines with either electron-donating

• indole 5 and a Ru(0) species F that was oxidized on the RVC anode to regenerate A. This electrochemical formation of indole, using easily available reactants and proceeding successfully under aqueous solution with simple undivided cell, was a green and convenient route towards indole. A series of

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• for different N-benzyl benzaldimines in moderate to good yields. In 1991, Shono’s research group described the electroreductive intramolecular coupling of aromatic diimines, carried out in DMF in the presence of methanesulfonic acid in a divided cell equipped with a lead cathode, a carbon rod anode

• -diimines. Later, in 2001, Yudin and co-workers described the parallel reductive coupling of aldimines using a spatially addressable electrosynthesis platform, which employed a stainless steel cathode, a sacrificial aluminum anode and a procedure adapted from Torii's earlier work including the use of PbBr2

• described a new electrochemical procedure to provide vicinal diamines involving the use of Sn electrodes as both anode and cathode in a divided cell, Mn(OAc)3·2H2O as additive and n-Bu4NOAc as electrolyte. Under these conditions, using aldehydes and amines as starting materials to form the imines in situ

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

• in a THF/MeOH solvent mixture, using a constant current electrolysis setup with a reticulated vitreous carbon (RVC) anode and a platinum cathode. The substrate scope was extensively investigated, and a broad array of N-aryl substituents was well tolerated, including electron-donating motifs such as

• . Based on these results and previous studies, a detailed reaction mechanism was proposed as shown in Scheme 12. The process begins with the oxidation of Cp2Fe at the anode to form Cp2Fe+, which then facilitates the deprotonation of the α-C–H bond of the 1,3-dicarbonyl compound by methoxide, generated at

• employed as a redox catalyst, Na2CO3 as a base, and n-Bu4NBF4 as the electrolyte, all participating in an undivided electrolytic cell with a reticulated vitreous carbon (RVC) anode and a platinum (Pt) cathode at a constant current of 10 mA, in a co-solvent mixture of MeOH/THF 2:1 for 3 hours to deliver the

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• . They consist of two electrodes – anode (where oxidation occurs) and cathode (where reduction occurs) – immersed in an electrolyte. Galvanic cell The redox reaction occurs spontaneously in these cells, converting chemical energy into electrical energy. The potential difference between the two electrodes

• processes and can work well as the anode and cathode. This electrode has high stability in the electrochemical environment and is easy to clean, but caution should be taken when using it as a cathode because of low H2 overpotential. Platinum electrodes are very popular and valuable as cathodes in the

• electrochemical synthesis of organophosphorus compounds. They are used as the cathode in more than 70% and as the anode in ≈30% of electrosynthesis processes. Nickel (Ni) electrode: Nickel is not usually used as the anode but as a sacrificial anode in electrosynthesis. Using nickel as the cathode has a better

Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters

• Olesja Koleda,
• Janis Sadauskis,
• Darja Antonenko,
• Edvards Janis Treijs,
• Raivis Davis Steberis and
• Edgars Suna

Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50

• ]. Accordingly, the electrolysis of monoester 9a in a 2:1 MeCN/H2O mixture in the presence of 0.025 M LiClO4 solution under constant current conditions (j = 12 mA/cm2) with graphite both as an anode and a cathode material afforded the desired N-tosylpyrrolidine 6a in 67% yield (Table 1, entry 1). The water

Electrochemical synthesis of cyclic biaryl λ³-bromanes from 2,2’-dibromobiphenyls

• Andrejs Savkins and
• Igors Sokolovs

Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32

• −2 led to 60% λ3-bromane 1a degradation, suggesting that cationic 1a, formed on the anode, decomposes on the cathode. To avoid the undesired cathodic decomposition of 1a, the cathode and anode chambers were separated, and further experiments were performed in a divided cell. Gratifyingly, the change

• change of the anode material from GC to RVC or BDD (entries 8 and 9, Table 1), variation of electrolyte amount (entries 10 and 11) or altering of counter anions in the supporting electrolyte (entries 12 and 13; for complete optimization results, see Supporting Information File 1, Table S1). With the

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• viable alternatives to conventional chemical oxidizing and reducing agents [31], electrochemical reactions not only enable substrates to undergo single-electron transfer at the cathode or anode, either directly or indirectly, generating highly reactive radical intermediates, but also allow direct

• elimination, produces C–H alkynylated arene 10, which then forms the final product 3 through intramolecular cyclization. Finally, the Cu(I) complex 9 produced via reductive elimination is reoxidized at the anode to regenerate the Cu(II) complex 4, completing the catalytic cycle. Yao and Shi developed the

• produce a chiral product 22. The reduced copper catalyst 24 and [AQDS–H]• are reoxidized to L3Cu(II)(CN)2 (25) and AQDS at the anode, respectively, completing the catalytic cycle. In the same year, following a similar approach, the Liu group explored a Cu-catalyzed photoelectrochemical enantioselective

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• recently showed that polymerizing negatively curved polycyclic arenes produced an amorphous covalent network. This network was able to mimic the structure and function of carbon schwarzites, serving as an anode material in lithium-ion batteries with high capacity [21]. Further exploration of bottom-up

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• fluorinated oxazolines 32 was also reported using an electrochemical approach in 2019 by Waldvogel and co-workers (Scheme 17) [40]. The authors used electrochemical oxidation to form p-tolyl-difluoro-λ3-iodane 10 on the anode using an undivided cell with platinium electrodes in a 1:1 solution of CH2Cl2 and

• via electrochemical oxidation of 4-iodotoluene at the anode, in a 5:6 HF:amine mixture to cyclise a range of phenolic ethers 33. Tolerance for substituents on both the aromatic ring and the alkene were shown, although the electronic requirements were quite narrow for reaction success. As the arene

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• anode and a foamed Ni cathode, at a constant current of 12 mA in DMSO at room temperature under atmospheric conditions. The reaction has been applied to more than 80 examples, including the late-stage functionalization of natural products and pharmaceuticals, as well as the synthesis and radiosynthesis

• cation is formed by oxidation of the substrate at the anode. This radical cation is subsequently deprotonated to produce an allyl radical. The allyl radical is further oxidized to form the allyl cation, which is then attacked by the nucleophilic sulfonamide, leading to the formation of the desired C–N

• oxidized at the benzylic position in good yields. A gram-scale test was conducted to confirm the potential for large-scale applications. According to the authors, the electrochemical oxidation of t-BuOOH at the anode leads to a tert-butyl peroxyl radical that activates the C–H bond at the benzylic position

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• Pt cathode and a Mg anode in the presence of carbon dioxide induced reductive C(sp3)−O bond cleavage at the benzylic position in diarylmethanol compounds and subsequent fixation of carbon dioxide to produce diarylacetic acids in good yield. This protocol provides a novel and simple approach to

• constant-current electrolysis in DMF using an undivided cell equipped with a Pt cathode and a Mg anode in the presence of carbon dioxide. On the other hand, carboxylation scarcely took place in DMF when other benzyl alcohols were used as substrates. Lundberg and co-workers recently reported similar results

• (Table 1, entry 6). In contrast, zinc was not effective as an anode material in the carboxylation, probably due to competitive electrochemical reduction of zinc ions generated by electrochemical oxidation of the zinc anode. The deposition of a black precipitate was observed visually at the cathode (Table

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• -derived NH-acylhydrazones to build 1,3,4-oxadiazole derivatives in good yields. The electrolysis was conducted under galvanostatic conditions in methanol using a carbon graphite anode and a platinum cathode. From a mechanistic point of view, in situ condensation of acylhydrazines 28 with α-keto acids 27

• -tetraethylammonium perchlorate solution under constant potential in a divided cell equipped with platinum gauze anode and nickel cathode. Such a transformation constituted a straightforward route to the corresponding fused s-triazolo perchlorates 46 in moderate to high yield. Coulometric analysis established that

• diazo compounds to react with alkenes, Chiba et al. developed the electrochemical construction of diphenylcyclopropanes 137 from benzophenone hydrazones 130 and methacrylic acid derivatives 136. The transformation was conducted on a large scale (60 mmol) in an undivided cell using graphite anode and

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• conditions of the potentiostatic electrolysis were the following: a two-compartment cell, a glassy carbon (GC) anode, DMF, the potential increased from 1.0 V to 1.4 V vs Ag/AgCl, KCl(sat.)), 2 F per mol of amine electricity passed, sodium tosylate (0.1 M) as a supporting electrolyte, and 2 equiv of 2.6

Electrochemical radical cation aza-Wacker cyclizations

• Sota Adachi and
• Yohei Okada

Beilstein J. Org. Chem. 2024, 20, 1900–1905, doi:10.3762/bjoc.20.165

• cyclization using the alkene 1 as a model (Table 1). Based on the conditions reported by Yoon and Moeller, the initial screening was carried out using tetrabutylammonium triflate (Bu4NOTf)/1,2-dichloroethane (1,2-DCE) solution. Carbon felt (CF) was used as an anode instead of reticulated vitreous carbon (RVC

• appropriate alkene (0.20 mmol), TFA (0.20 mmol), and CH3CN (0.4 mL) were added to a solution of Bu4NOTf/1,2-DCE (0.10 M, 3.6 mL) while stirring at room temperature. The resulting reaction mixture was electrolyzed at 1 mA using a CF anode (10 mm × 10 mm) and a Pt cathode (10 mm × 20 mm) in an undivided cell

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• cell equipped with a platinum-coated cathode and a carbon-filled PPS (polyphenylene sulfide) micro-channel anode separated by a polyetheretherketone (PEEK) gasket [40]. Further experimental details and characterization of new compounds are given in Supporting Information File 1. General procedure A

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• chamber. The hydrogen (H2) or H2O were oxidized at the anode to form protons (H+) that moved to the cathodic chamber, and the protons were reduced to monoatomic hydrogen species (absorbed hydrogen, Had). Thus-generated Had reduced the substrate passed through the cathodic chamber. MEA eliminates the need

• of 6a using an aqueous proton source instead of hydrogen. The use of DSE® as an anode and H2SO4 aq as an anolyte was effective, and 7a was obtained in 80% yield (Scheme 5b). Reduction of pyridines to piperidines As mentioned previously, reduction of pyridines to piperidines is important for organic

• ) a PEM reactor and (b) MEA. Hypothesis of the trap of quinoline on membrane and tetrahydroquinoline and the effect of adding an acid. Recycled use of MEA for the electroreduction of 6a in the presence of PTSA (0.10 equiv). Reaction conditions: anode catalyst, Pt/C; cathode catalyst, Pt/C; 6a, 1.5

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• of a host of functional groups [68]. This approach can also be applied for nucleophilic fluorination of benzylic substrates. This occurs via sequential electron-transfer and proton-transfer steps, as outlined in Figure 35 [87]. Single-electron oxidation of benzylic substrate I at the anode generates

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

• Yukang Wang,
• Yan Yao and
• Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

• by anodic oxidation and visible light irradiation of the Ce species in a sequential fashion [38][39][40][41][42][43][44][45]. Therefore, the anodic electrode potential for this process could be substantially reduced. In doing so, a low working potential at the anode offers the opportunity for

• efficiency. Results and Discussion Our study of this new electrophotochemical metal-catalyzed decarboxylative cyanation commenced with the evaluation of various combinations of Ce and Cu catalysts. A simple undivided cell using a carbon felt, inexpensive and practical porous material as the anode, and a Pt

• yields are of isolated products. Unless otherwise noted, reaction conditions were as follows: 0.2 mmol acids, 0.4 mmol TMSCN, CeCl3 (10 mol %), Cu(OTf)2/BPhen (5/6 mol %), 0.05 mmol BTMG, 0.2 mmol TBABF4, 0.5 mmol TFE, 3.5 mL of CH3CN, 0.5 mL of DMF, carbon felt as the anode, Pt as the cathode, under N2

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

• presence of H2O and 5 mol % of 1,3-dicyanobenzene (1,3-DCB) [55] under visible-light irradiation at 0 °C (Table 1, entry 1) [56]. Ammonium salts containing other counter anions also afforded 3aa in slightly lower yields (Table 1, entries 2 and 3). Changing the sacrificial anode or cathode did not improve

• alkene 2 to provide alkyl radical species B. Further single-electron reduction by 1,3-DCB•− or at the cathode followed by protonation of B provides hydroarylation product 3. Meanwhile, the sacrificial anode is oxidized to form Al cations. Although the exact role of visible-light irradiation in the

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• ™ Impact instrument (electrospray ionization). Melting points were determined on a Fisher–Johns melting point apparatus. X-ray diffraction study The X-ray diffraction dataset of compound 3b was recorded on an Agilent SuperNova diffractometer using a microfocus X-ray radiation source with copper anode and

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

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

• . Finally, single electron oxidation of 169 at the anode, followed by rearomatization via proton-transfer forms the alkylated heterocycle 170. As discussed in Scheme 25, the Ni-catalyzed cross-electrophile coupling between redox-active esters and aryl halides requires the addition of a stoichiometric

• -halides [115]. Their optimized reaction conditions required a NiII precursor, 2,2’-bipyridine (bpy) as ligand, silver nitrate (AgNO3) as an additive and the combination of a magnesium (Mg) sacrificial anode and a RVC cathode (Scheme 35A). A crucial discovery in advancing this methodology was the in situ

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• in CH3CN) in CH2Cl2 (4a–h), CH3CN (5a–c, 6a,b, and 10c) and potentiostat–galvanostat Elins P-45X. X-ray data collection was performed on an Agilent SuperNova diffractometer using a microfocus X-ray source with copper anode (Cu Kα radiation, λ = 1.54184 Å) and Atlas S2 CCD detector. The diffraction

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• radical acceptor moieties. Therefore, we investigated the origin of this selectivity under electrochemical conditions. Results and Discussion Anodic oxidation of uridine derivative 1 was performed in a CH2Cl2/Bu4NPF6 (0.1 M) electrolyte system using a carbon felt (CF) anode and a Pt cathode in the

• potential than 1 (Figure 2C, grey line); thus, it was subsequently oxidized on the anode to afford the halonium ion (Cl+), which can react with 1 to form unstable N−Cl species (B) in situ (Figure 4). Although we cannot detect the chlorinated intermediate of 1, electrolysis of N-propylcarbamate derivative

• of 5 mA (3 F/mol, 57.9 C) through the CF anode (1 × 1 cm) and the Pt cathode (1 × 1 cm). The reaction mixture was concentrated in vacuo and Et2O (20 mL) was added. The resulting precipitate was removed by filtration through a short silica gel pad under reduced pressure. The filtrate was concentrated