Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• (89%). Interestingly, the fusion of two azulene units at peri-position induces the significant orbital interaction, resulting in a very narrow HOMO–LUMO gap in 172. Consequently, 172 exhibits NIR absorption properties (λmax = 1180 nm, tail to 1720 nm) and reversible redox behaviours (electrochemical

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

• radical C, which adds to the N-arylacrylamide, followed by intramolecular cyclization and deprotonation to form the final products 19. To further expand the radical difunctionalization toolbox, electrochemical approaches have emerged as a green and efficient alternative, offering precise redox control

• 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

• selection, solvents, and current density, the best results were obtained using tetrabutylammonium bromide as the catalyst in CH₃CN, with a low catalyst loading of 2 mol %, and palladium wire as the cathode, yielding the target compound in 81% yield. This study capitalized on the use of bromide ions as redox

Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates

• Alexander S. Budnikov,
• Igor B. Krylov,
• Fedor K. Monin,
• Valentina M. Merkulova,
• Alexey I. Ilovaisky,
• Liu Yan,
• Bing Yu and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96

• -centered radical from diisopropyl H-phosphonate (2a). In addition, the anion affects the redox properties of the copper ion, and thus the optimal choice is important to achieve both sufficient oxidative properties and catalyst recycling by reoxidation with O2. The employment of Mn(acac)3 and FeCl3, which

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• addition, the method could be scaled up to a gram scale. Redox-driven ylide reactions have gained increasing attention to tackle several disadvantages of traditional ylide-type reactions, such as use of reagents in excess and harsh reaction conditions. For example, Werner and co-workers (2019) reported a

• catalytic Wittig reaction using phosphetane oxide 412 as redox cycling catalyst using silanes as the reductant to convert aldehydes and α-bromoesters into the corresponding cinnamate esters 44, 154, and 413. The reaction proceeds via formation of nucleophilic phosphane 414 (Scheme 87A) [147]. Moreover

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• is a particular interest in the obtainment of organic molecules with well-balanced redox potentials in the excited state that can act as bimodal photocatalysts, facilitating their use in oxidative and reductive quenching cycles. In this sense, it is crucial to understand the molecule's structure

• absorption profile in the visible region, ii) a long lifetime of the excited states, and iii) balanced redox potentials in both the ground and excited states [7]. In 2018, Zeitler and her collaborators conducted an innovative and in-depth study on modulating the photochemical properties of a family of donor

• –acceptor cyanoarenes [8]. They employed various nitrogen donor molecules attached to diversely substituted acceptor cores. This systematic approach allowed the authors to develop new organic photocatalysts (PCs) with strong reductive or oxidative properties based on the different redox potentials. Although

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

• Electrochemical reaction cells When a redox reaction occurs indirectly, chemical energy is transformed into electrical energy. A device that facilitates this conversion is known as an electrochemical cell. Electrochemical reaction cells are divided into two primary categories: galvanic (voltaic) and electrolytic

• . 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

• resistance, and maintain ion balance (e.g., LiClO4, n-Bu4NBF4), and active electrolytes, which participate directly in redox reactions, acting as oxidizing or reducing agents (e.g., H2SO4, Et4NOH). Choosing the proper electrolyte affects reaction efficiency, selectivity, and overall performance. Electrodes

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

• decarboxylation/cyclization conditions, and the respective 2-aminoproline derivatives 6a–c were obtained in 49–75% yield. Redox-sensitive 4-anisoyl and 4-cyanobenzoyl groups-containing monoesters 9d,e are also suitable as substrates as evidenced by the formation of 6d,e in 38–63% yields. Not only N-tosylates

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• selectivity and the preservation of sensitive biological structures when appropriate redox potentials of photocatalysts are applied to the targeted amino acid. Additional advantages of photoinduced reactions include the ability to perform the reactions rapidly (typically <15 minutes). It was only in the late

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• [17][18]. An important drawback of this solvent is the difficulty of its removal from the reaction crude, and extractions with water are commonly employed before purification. Depending on the reaction conditions, DMSO can be transformed into different products, e.g., under redox conditions, DMSO can

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

• substrates that do not form the desired electrochemical oxidation product see Supporting Information File 1, Scheme S1). A series of control experiments was performed to rationalize the observed reactivity trends (Scheme 2). The measured redox potentials EP/2 for 2,2'-dibromo-1,1'-biphenyls 4a–g (from 1.77 V

• correlation between Ep of the redox event and the square root of the scan rate (Scheme 3B) suggested that compound 4a is not significantly adsorbed on the electrode surface [23]. Comparison of the jp vs v0.5 slope with our previously obtained results for the anodic oxidation of aryl bromides 6a (two-electron

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• constriction (ground-state destabilization) are also possible [140][168][169][170]. The metals can sometimes participate in redox catalysis [171], and may be stabilized by the cage structure [160][172][173][174]. The organic part of the MOC has also been levied as a hydrogen-bond donor to activate an

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• diverse catalyst types and applications. The first section is dedicated to metal-based photocatalysts. Complexes involving metals such as osmium and ruthenium, have dominated red-light photoredox catalysis because of their ability to absorb low-energy photons and sustain redox cycles via stable excited

• ability to operate under low-energy light conditions, opens up new avenues for main-group redox catalysis in organic synthesis. By leveraging light excitation to enhance the reducing power of the bismuth complex, the study showcases the potential of main-group photoredox systems to complement traditional

• determined the redox potentials of several squaraine derivatives (40, 41, 42, and 43 presented in Figure 6a) which exhibit oxidation potentials at the excited state ranging from −1.22 V to −1.58 V vs SCE and reduction potentials at the excited-state between 0.84 V and 1.22 V vs SCE. In particular, derivative

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• also been reported as model systems to investigate redox charged species experiencing evolutions from neutral non-aromatic, to antiaromatic, and to aromatic structures. Xia and co-workers recently reported a modular method to synthesize molecules containing cyclobutadienoid (CBD) groups [18][19][20

• stabilization of such redox states. Results and Discussion Electrochemistry Figure 2 shows the electrochemical cyclic voltammograms of 1 and 2, in which two reversible oxidation processes can be observed. By considering the half-wave potential values obtained from the cyclic voltammograms, two one-electron

• give rise to two naphthylene-centered cations located at both sides of the molecule. The connection path would be partially interrupted by the angular topology, thus accounting for the more similar redox potentials. Electronic spectroscopy The UV–vis–NIR electronic absorption spectra of the neutral and

Synthesis of disulfides and 3-sulfenylchromones from sodium sulfinates catalyzed by TBAI

• Zhenlei Zhang,
• Ying Wang,
• Xingxing Pan,
• Manqi Zhang,
• Wei Zhao,
• Meng Li and
• Hao Zhang

Beilstein J. Org. Chem. 2025, 21, 253–261, doi:10.3762/bjoc.21.17

• tetrabutylammonium iodide (TBAI)/H2SO4 reduction system using sodium sulfinate as key component, thus eliminating the need for thiols and redox reagents commonly used in traditional methods. Various disulfides and 3-sulfenylchromones were obtained in moderate to excellent yields through this methodology. Mechanistic

• disulfides from sodium sulfinate without the use of additional redox reagents remains a challenging task. 3-Sulfenylchromones are an important class of heterocyclic compounds with unique skeletons in nature that play an essential role in drug synthesis and development. To synthesize these compounds, direct C

• additional redox reagents to the reaction, making this method a valuable addition to the synthesis of disulfides. Furthermore, this approach can be extended to the synthesis 3-sulfenylchromones, thereby broadening its application. Results and Discussion Reaction conditions were optimized using sodium p

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

• electron transfer to the metal catalyst without the need for chemical redox agents, thus providing milder and more sustainable reaction conditions (Figure 2) [32]. Electrochemical reactions can be performed at low potentials, thereby suppressing side reactions, and chemoselectivity and reactivity can be

• has emerged as a potential synthetic tool for the formation of new C–C, and C–heteroatom bonds using electricity to replace the stoichiometric amounts of conventional chemical redox reagents [47]. C–C Bond formation In 2019, the Ackermann group established a synthetic method for isoindolones using a

• asymmetric C(sp3)–H alkynylation of tertiary cyclic amines by merging Cu(II)/TEMPO catalysis with electrochemistry to yield chiral C1-alkynylated tetrahydroisoquinolines (THIQs) (Figure 5) [50]. As a co-catalytic redox mediator, TEMPO plays an essential role in the formation of iminium intermediate 15 and in

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• is more nuanced [10][11]. Subsequently, literature and computational examples reveal a leitmotif for CpH-PAH-based redox-active carbon-rich materials. Results and Discussion From competitive titrations against 9-C6F5-fluorene (pKa = 28.14 in CH3CN) [12][13] and (4-Me-C6F4)(C6H5)CHCN (pKa = 26.98 in

• pentabenzocorannulene would produce air-stable radical and ionic PAHs, and that coupling such fragments would lead to stable redox-active carbon sheets. Conclusion In conclusion, the “surprise” in the surprising pKa for BIC and FIC was in our expectation of the deprotonated forms as poorly delocalized fluorenyl anions

• unforeseen new material designs (e.g., redox-active electrooptical materials). Methods pKa measurements in acetonitrile The experimental setup and methodology for the pKa determination of BFC and FIC in acetonitrile was essentially the same as described in detail in previous papers [12][13]. A brief

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• . Changes in the reduction or oxidation state can alter redox behavior, thereby affecting catalytic activity. For example, it has been reported that 2,3,5,7,8,10,12,13,15,17,18,20-dodecasubstituted free-base porphyrins and their mono/diprotonated derivatives are highly distorted with a good access to the

• photocatalysts. The results demonstrated that these substituents significantly influenced the redox properties of the porphyrins, yielding up to 86% with the electron-poor meso-tetrakis(pentafluorophenyl)porphyrin (67), compared to H2TPP and other electron-rich systems. This finding indicated that fine-tuning

• batteries, due to the ease of their structural modification, rich redox chemistry, and robust coordination M–N4 environment [100][101][102][103][104][105]. The key processes employed in energy transfer and storage are the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• )rotaxane framework The rotaxane framework is often deployed as a molecular device in which the positional relationship between the axle and wheel is controlled by external stimuli [14][32]. Acid–base, photoisomerization, redox, ion recognition, solvent polarity, or heating treatment is generally used for

• stilbene has been generally used to control the position of CD in the rotaxane structure [14][15]. In addition to the photoisomerization–based system, redox-based structural control was reported by Stoddart and co-workers in 2008 using α-CD-based [2]rotaxane bearing a dumbbell molecule comprising

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

• photoredox catalysis [26][27][28]. These methods allow selectivity to be controlled despite the presence of the complex cocktail of radical species generated by hydroperoxides under redox or homolysis conditions. The main challenge in selective radical peroxidation is the wide range of possible pathways

• involving radical intermediates from hydroperoxides under redox conditions (Scheme 3). The reactivity of O-centered radicals is less predictable and more diverse depending on radical structure and substrate pattern than the chemistry of C-centered radicals [29][30]. Generally, peroxy radicals have a

• -scission [31][32], which can lead to side reactions. Some aspects of the rich metal–peroxide redox chemistry have been discussed in previous reviews [33]. Specifically, the radical functionalization of C–C bonds accessed through the transition metal-mediated reduction of organic peroxides has been covered

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• to serve as a proton source for redox reactions at the metal. 3. The electronic properties of the porphyrin, especially the low oxidation potential, should not be increased. We have chosen four-fold meso-3,4,5-trimethoxyphenyl-substituted Ni porphyrin as the electron-rich system, however, the post

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• reversible oxidation waves as shown from the CV data (Figure 6 and Table 1). This reversibility is crucial for the regeneration of dyes following redox processes. The compounds display ionisation energies (IEs) of −5.38 eV, −5.34 eV, and −5.40 eV for 3a, 3b, and 3c, respectively, with electron affinities

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• application of the Mukaiyama redox condensation using N-iodosuccinic imide (NIS) afforded 10b. Hydrogenation resulted in defunctionalization to give 10c. Transformation of OH-4 to a triflate and subsequent reaction with sodium azide afforded gluco-configured product 10d. The latter was transformed to

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

• orbital during enolate formation, thus providing mild redox conditions. After anodic oxidation, a carbon-centered radical at the α-position is formed, which undergoes stereocontrolled C–C-bond formation with the silyl ether, forming a trimethylsilyl (TMS)-ketyl radical. A second anodic one-electron

• ) as the redox mediator, this method showed excellent tolerance across various arenes and alkenes. The selective LSF of biorelevant complex molecules demonstrated significant potential for drug exploration (Scheme 42a). One year later, the same group disclosed the dehydrogenative cross-coupling of two

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• : antioxidant activity; catechol thioethers; heterocycles; redox-transformations; thiones; Introduction Synthetic derivatives of polyphenols, in particular catechol (hydroquinone), represent a promising group of pharmacologically active substances [1][2]. Catechol-containing compounds demonstrate

• heteroatoms (nitrogen, sulfur, selenium, tellurium, etc.) as well as redox-active functional groups allows one to vary significantly the biological activity of such compounds. Heterocyclic molecular blocks are widely used in medicinal chemistry [12]. Thiazole, oxadiazole, triazole, imidazole, and other

• ) < 1,3,4-oxadiazole derivatives (1.37–1.39 V). The redox properties of catechols 1–9 were studied by cyclic voltammetry (CV) (Table 1). In the anodic area, the electrochemical profile for catechol thioethers 1–5 represents two successive irreversible oxidative stages. The first two-electron peak is