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

• salts and TEMPO as the radical initiator/oxidant couple that promoted the intramolecular radical cyclization of suitable 1,3-dicarbonyl Ugi adducts 54 and 55 (Scheme 45) [108][109]. The stabilization of the enol in the 1,3-dicarbonyl Ugi adduct allows single-electron transfer (SET) with the anion

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• receptors; molecular recognition; monosaccharides; tryptophan; Introduction Tryptophan plays a crucial role in a variety of biological processes [1][2]. For example, it is critical for electron transfer in proteins [3] and is a key component of several membrane proteins as well as short antimicrobial

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• transform molecules. Intriguingly, photocatalysts typically absorb harmless visible light and can be chosen ad hoc to trigger the desired chemistry. Indeed, the photocatalyst–substrate interaction can occur via energy transfer [4][5][6][7][8], single-electron transfer [9][10][11][12], or hydrogen-atom

• in enhancing the mixing efficiency and increasing the exposure of the surface of the reaction mixture to light. Additionally, the formation of compound 8.2 was associated with the observation of an initial molten state of the mixture, which could have promoted single-electron-transfer processes that

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

• '-dibromo-1,1'-biphenyls 4a–m. A closer inspection of the electrochemical behaviour of compound 4a revealed an irreversible electron transfer at scan rates up to 1 V s−1 (Scheme 3A) indicating that one or more rapid chemical steps are following the electrochemical step [22][23]. Besides, the observed linear

• oxidation) and 6b (one-electron oxidation) into the respective bromine(III) species (Scheme 3C) [17] demonstrated a more similar behaviour to 6b suggesting that revealed oxidation is a single-electron-transfer process. It is important to note that this comparison assumes that the diffusion coefficients of

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• photoinduced electron transfer [8][9]. Thanks to their notable photophysical properties, pyrazoles are applied in OLED technology [10]. Noticeably, in its ground state, pyrazole (C3H4N2) is an aromatic molecule that follows Hückel's rule, with two formal double bonds and a lone pair on one nitrogen generating

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

• catalysis in recent years not only with heavy metals such as ruthenium and iridium [1][2][3][4][5], but also with lighter elements [6][7][8]. This field of light-mediated organic transformations relies on the use of a photocatalyst to promote radical reactions through electron transfer between this former

• effects play a role in reducing the energy of the d orbitals and improving their overlap with the ligand orbitals, thereby facilitating electron transfer, the occurrence of metal-to-ligand charge transfer (MLCT) is also strongly influenced by other factors. Specifically, MLCT competes with metal-centered

• excitation to the triplet state from the ground state S0. This effect mitigates rapid back-electron transfer from the singlet excited state to the ground state, extending the excited-state lifetime of the photocatalyst. Since the T1 → S0 transition is spin-forbidden, the process increases the overall

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

• attracted a growing interest in recent times, both from fundamental and technological reasons [9][10][11]. Antiaromaticity destabilizes the ground state of organic molecules by raising their highest energy occupied molecular orbitals, thus allowing for easy oxidation, doping, and electron-transfer reactions

Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• intermediate D via intramolecular radical cyclization. A single-electron-transfer (SET) process then occurred between the radical B and the radical D, resulting in the generation of cationic intermediate E, difluoroacetate anion and PhI. Finally, the product 3a was obtained after the deprotonation by

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

• electrochemistry and copper catalysis for various organic transformations. Keywords: copper; electrochemistry; radical chemistry; single-electron transfer; sustainable catalysis; Introduction Transition-metal-catalyzed cross-coupling has emerged as an effective method for forming carbon–carbon (C–C) and carbon

• 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

• 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

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• or radical (Figure 1). The latter is typically operative when the reaction is carried out under oxidative conditions, usually in the presence of O2 and TEMPO, involving the formation of radical species through single-electron transfer (SET) from a copper catalyst to a precursor. Subsequent addition

• reaction proceeds through an initial single-electron transfer from NFBS assisted by the active copper species, followed by intermolecular hydrogen-atom transfer from the carbazate. The nitrogen radical intermediate I thus formed is decomposed into the acyl or alkyl radical intermediates II and III

Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation

• Perry van der Heide,
• Michele Retini,
• Fabiola Fanini,
• Giovanni Piersanti,
• Francesco Secci,
• Daniele Mazzarella,
• Timothy Noël and
• Alberto Luridiana

Beilstein J. Org. Chem. 2024, 20, 3274–3280, doi:10.3762/bjoc.20.271

• pathway for the functionalization of an electron-deficient olefin is the Giese reaction (Figure 1) [6][7]. This reaction involves the hydroalkylation of the olefin via radical addition (RA), followed by either hydrogen-atom transfer (HAT) or single-electron transfer (SET) and protonation. Traditionally

Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

• Jón Atiba Buldt,
• Wang-Yeuk Kong,
• Yannick Kraemer,
• Masiel M. Belsuzarri,
• Ansh Hiten Patel,
• James C. Fettinger,
• Dean J. Tantillo and
• Cody Ross Pitts

Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259

• nanotechnology [5], liquid crystal design [6][7][8][9][10], and the study of energy-transfer [11][12] or electron-transfer [13][14][15][16][17] processes. We also posit that lower-order [n]staffanes (i.e., n = 2 or 3) are potentially valuable C(sp3)-rich bioisosteres [18][19] that have been seemingly overlooked

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

• ring attacks the activated alkene, if it is too electron-poor then it is not reactive enough. Moreover, if it is too electron-rich, then it preferentially oxidises via a single electron transfer mechanism which deactivates the ring as a nucleophile. The synthesis of fluorinated oxazepanes 36 was

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

• to absorb significant amounts of visible light photons, which allows them to reach an excited state. The excited porphyrin molecule is likely to undergo energy transfer (ET; photosensitization) or single-electron transfer (SET; photoredox catalysis) to substrate molecules (Figure 13). In

• and a photosensitizer, facilitating photoinduced electron transfer (PET) to form the active cation radical B, and intersystem crossing (ISC) for energy transfer to generate the triplet carbene C. Radical B then reacted with biradical C, producing the new radical D, which accepted an electron from the

• initiated the reaction pathway. The authors proposed that under light irradiation, the porphyrin transitioned to its excited state, generating a phenyl radical through photoinduced single-electron transfer (Figure 15c). This phenyl radical then added to the furan (heteroarene), forming an aryl radical

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

• small thickness are used. Moreover, this polymer can dissolve in water owing to the hydrophilicity of the CD units. Based on the above method, a conjugative polymer containing triphenylamine- (TPA)-modified β-CD was reported (Figure 13B) [82]. In this system, the excitation energy and electron transfer

• were observed from the TPA to the conjugative polymer backbone included by perfectly arylated β-CD. TPA units located near the axle polymer are likely to induce an electron transfer, while those located far from the axle polymer tend to cause an excitation energy transfer. Thus, the polymer unit

• excited by the excitation energy transfer is located far from the TPA units, preventing quenching via electron transfer. Meanwhile, around 200 TPA units were included in one polymer molecule. The abovementioned property is induced by the nature of CD, which has many modifiable substituents (hydroxy groups

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

• oxidized by the excited photocatalyst to give the benzyl radical D and CO2. Further, single electron transfer from (Acr·-Mes) C to TBHP results in the ground state photocatalyst (Acr+-Mes) A and tert-butoxy radical E, which abstracts the hydrogen atom from TBHP to yield tert-butylperoxy radical F. The

• radical–Ru(III)(OH) intermediate, which provides the cationic intermediate from phenol via electron transfer. The reaction of cation D with TBHP results in the mixed peroxide 87 [84]. However, this mechanism was later doubted based on the experimental data of [Rh2(cap)4]-catalyzed peroxidation of phenols

• assumed to react with TBHP to form vanadyl(IV) alkyl peroxy complex, which decomposes to vanadyl(V) hydroxide E and tert-butoxy radical A as a result of homolytic O–O bond cleavage with concomitant electron transfer. Vanadyl(V) hydroxide E then reacts with TBHP to provide tert-butylperoxy radical B. A

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

• ; perfluorinated aliphatic carboxylic acids; porphyrin synthesis; Introduction Metal porphyrins are prosthetic groups in a number of essential biomolecules, including hemoglobin, chlorophyll, and cytochromes, supporting processes such as oxygen transport, photosynthesis, and electron transfer [1][2][3][4][5

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• the respective arylation product [50][51]. Lastly, arylation can occur through single-electron transfer (SET), where a cation radical obtained from aromatic hydrocarbons with high electron density yields the desired arylated product [52]. In this review article, we will provide a comprehensive

• state, eosin Y*. This excited state further undergoes oxidation via a single-electron-transfer (SET) reaction with Ar2IBF4 26, producing eosin Y+ and a phenyl radical 30 (Scheme 10). The radical intermediate 30 selectively binds to the C2 position of either quinoline or pyridine N-oxide, forming

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• as a •OH adduct of DMPO (DMPO-OH, Figure 5b(ii)) revealing that electron transfer reaction was also occurring. Using DEPMPO as a spin trapping reagent, detection of O2•– was tried and some radical adducts were detected, but without being clearly identified (Figure 5c(i), (ii)). The reason of the

• same time, unusually fast conversion of O2•– to •OH was also suggested in this system. The results above suggest that catC60-lip generated both types of ROS (1O2 and •OH) via energy transfer and electron transfer mechanisms. The present results are in line with previous studies of photoinduced ROS

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• Scheme 6. Based on the results reported by Zeitler [28], several mechanisms are involved in the oxidation of N-Ph-THIQ. The most probable involves the photoexcitation of the EDA (Electron Donor-Acceptor) complex promoting an electron transfer from N-Ph-THIQ to BrCCl3 to afford the amine radical cation

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• been widely investigated in the past decades for application as fluorescent dyes [3][4][5], chirality inducers [6][7][8], acceptors for photoinduced electron transfer (PET) [9][10], and components of supramolecular assemblies [11][12][13][14]. Owing to the stable π-electronic systems showing unique

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

• sulfamidyl radicals via a concerted proton-coupled electron transfer (PCET). This process occurs after the formation of a hydrogen bond between dibenzenesulfonimide and n-Bu4NOAc. The formed sulfamidyl radical can directly react with the (hetero)aromatic ring. Subsequent anodic oxidation produces a

• , several structurally diverse aromatic acetals have been synthesized. Dehydroabietic and norcholanoic acid derivatives have been effectively modified using the developed protocol. The reaction is reported to involve the oxidation of the benzene core, followed by electron transfer to the radical cation, and

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• research [11][12], particularly focusing on innovative approaches to synthesize natural or bioactive compounds [13]. In the carboamination of alkenes, amides are used in photoredox cyclizations under proton-coupled electron transfer (PCET) conditions [14][15][16][17]. An alternative method to generate N

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

• the electrochemical properties of functionalized catechols allows one to suggest the mechanism of their electrooxidation, establish electron transfer centers, and predict antioxidant activity based on electrochemical data. To determine electron-transfer centers, the oxidation potentials of the

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• synthesis. The higher-energy collisional dissociation (HCD) releases the characteristic reporter ion at m/z 126.1277. In case the electron-transfer dissociation (ETD) is used the DMP-tag yields the reporter ion at m/z 114.1275. Of note, although ETD is more selective towards fragmentation of the peptide