On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• such diradicals and we group the molecules in accordance with their type of conjugation. Kekulé-conjugated diradicals Trityl radicals and trityl-derived diradicals have been reported to be instable especially under light irradiation and in the presence of oxygen. As for the monoradicals, also

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• response, respiratory, vasodilation, apoptosis, tumor growth, and cardiovascular system [1][2]. Nitric oxide (NO) is released as product of the NADPH and oxygen-dependent oxidation of ʟ-arginine to ʟ-citrulline under the catalysis of the enzyme nitric oxide synthase (NOS) [3]. There are three distinct

• a dihedral angle of 49.86(10) 86.22(11)° with the phenyl rings C6–C11 and C18–C23, respectively. The angle between both phenyl rings is 70.76(11)°. The stereochemistry around the double bond is Z, allowing an intramolecular N–H···O hydrogen bond between one of the carbonyl oxygen atoms and the amino

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• ) derivatives. Push–pull substitution on the 2 and 3 position as well as introduction of oxygen or nitrogen at position 7 of the NBD scaffold have led to the development of a new family of photoswitches. We studied the potential conversion of norbornadiene to quadricyclane (QC) isomers. As main investigation

• the corresponding boronic acid in a degassed toluene/H2O mixture (4:1, v/v) which was heated to 80 °C for 18 h (for detailed information see Supporting Information File 1). Using the described procedure, the oxygen containing derivatives O-NBD2 and nitrogen substituted N-NBD2 were successfully

• absorption maximum and onset was observed for the heterocyclic derivatives in relation to their isocyclic analogues. Basic principle of the NBD to QC conversion and vice versa. The bridge-atom at position 7 was varied to carbon, oxygen or nitrogen. The back-conversion induced via heat or a catalyst can

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

• synthesis of various organophosphorus compounds through the formation of phosphorus–carbon, phosphorus–nitrogen, phosphorus–oxygen, phosphorus–sulfur, and phosphorus–selenium bonds. The impact of different electrodes is also discussed in this matter. Graphite, platinum, RVC, and nickel electrodes have been

• organophosphorus compounds, in which phosphorus is attached to carbon or heteroatom centers. In this article, we describe recent advances in electrochemical green methods for the synthesis of various organophosphorus compounds through the formation of phosphorus–carbon, phosphorus–nitrogen, phosphorus–oxygen

• reaction. Some of their applications include hydrogen and oxygen production, metal electroplating, and organic compound synthesis using electrochemical methods. Depending on the reaction conditions, these cells can be divided or undivided. Divided vs undivided cells In divided cells, oxidation and

New advances in asymmetric organocatalysis II

• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60

• commonly defined as a form of catalysis where a small organic molecule, an organocatalyst, accelerates a chemical reaction. Unlike previously regarded traditional catalysts involving metals or enzymes, organocatalysts are composed of nonmetal elements, such as carbon, hydrogen, nitrogen, oxygen, phosphorus

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• set out to elucidate it by using DFT computations (Figure 2). As we have chosen as substrate in our experiments a self-prepared mixture of E- and Z-isomers (9:1) of N-acyl hydrazone 1, which allows for additional binding to oxophilic calcium via the carbonyl oxygen, we did not know a priori which of

• -tetrahedral coordination environment with cyanide, stemming from a common reagent (vide infra) and binding to the metal in a preferred side-on (π-complex) mode [54]. When the hydrazone substrate enters the catalytic cycle, it coordinates also as a bidentate ligand to calcium via oxygen and nitrogen atoms

• [1,2]H shift is orbital symmetry forbidden and has, hence, a high barrier of 39.8 kcal·mol−1, and also because a – conceivable – intermittently at carbonyl oxygen protonated species (i.e., on an iminol-type pathway) is considerably higher in energy than 10 or 11. The TMS-bound product 12, proposed in

Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• moderate to good yields. Subsequently, we investigated the scope of cyclobutanones and their analogues in the domino cyclization to access structurally diverse spirotetrahydroquinoline derivatives (Scheme 2). Heterocyclic analogues incorporating oxygen or sulfur atoms within the four-membered ring proved

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

• macrocycle [74][75]. 2 Ethers We now turn our attention from alkanes to what is arguably the simplest heteroatom-containing functional group: the ether. The presence of oxygen within a carbon chain offers several new opportunities for engagement by an introduced fluorine atom. First, we will consider what

• happens if fluorine is introduced onto one of the carbons that is directly attached to oxygen (Figure 6). This makes possible a hyperconjugative interaction between a lone pair on oxygen and the σ* orbital of the C–F bond (I, Figure 6) [76]. This interaction biases the rotational profile about the O–C(F

• -hybridised oxygen atom. When one fluorine is introduced into this scaffold in the form of a fluoromethyl group (43, Figure 6), the gross conformation is little changed, but notably the fluorine preferentially resides at an endo position (oriented back towards the aryl moiety) which enables nO → σ*C–F

Recent advances in allylation of chiral secondary alkylcopper species

• Minjae Kim,
• Gwanggyun Kim,
• Doyoon Kim,
• Jun Hee Lee and
• Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

• complex's chemical behavior (Scheme 6). Among the analyzed four-coordinate boron species, the unreactive trialkoxyborate complex A exhibited the most compact B–C bond at 1.621 Å. Following a clear trend, the B–C bond distance progressively lengthened as oxygen atoms were substituted with elements of lower

• energy compared to (S,S)-TS9. Both transition states demonstrated a lithium center's coordination involving bromide, benzoate, and ligand oxygen atoms. The (S,R)-TS8 transition state exhibited a significantly shorter Li–Br interaction distance (2.81 Å compared to 3.74 Å in (S,S)-TS9), offering

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

• tetrahydropyran-containing amino acid derivatives via anodic decarboxylation of N-acetylamino malonic acid monoesters to generate a stabilized carbocation (Hofer–Moest conditions), which were then reacted with a tethered oxygen nucleophile [4]. In this follow-up study, we demonstrate that N-protected amines are

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

• oxygen [42]. Through energy transfer (EnT) from the ruthenium-based photocatalyst to triplet oxygen, singlet oxygen is produced in a targeted manner, which oxidizes histidine to an endoperoxide, significantly increasing its reactivity toward nucleophiles (Figure 4A). This strategy employs a

• functionalized ruthenium complex and a fragment crystallizable (Fc) ligand anchored to a magnetic bead, enabling the localized generation of singlet oxygen near antibodies (Figure 4B). The short lifetime and limited diffusion of singlet oxygen ensure exclusive reactions with proximal histidine residues. This

• intermediates can lead to protein denaturation or aggregation [61]. Because photoredox reactions often generate highly reactive species (such as radicals or singlet oxygen), long exposure times could cause unwanted side reactions, including the degradation of 3D structure of the protein or antibody. A short

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

• (CuCl2, NaNO2, TEMPO) using molecular oxygen as a terminal oxidant have also been used [12]. Nevertheless, neither of these conditions was successful when they were applied to methanol to generate formaldehyde, because overoxidation is an important side reaction in these cases [12][13][14][15]. However

• products (products 2 to 5, Scheme 4). In other cases, under acidic and thermal conditions, DMSO can undergo a Pummerer-type process in which, upon activation of the sulfoxide oxygen, a reactive methyl(methylene)sulfonium ion (MMS) is formed (Scheme 5) that acts as an active electrophile. Depending on the

• -aza-Prins cyclization reaction of homoallylic amines with disulfides and DMSO under copper catalysis, where DMSO acts as a solvent and a formaldehyde source at the same time (Scheme 13) [48]. This protocol represents a versatile method for the construction of oxygen-containing heterocycles, in which

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

• the molecule. In this regard we performed the acylation of starting compound 8o using pivaloyl chloride. The process was carried out with 3-fold excess of the aforementioned reagent at reflux in MeCN for 3 h. As a result, product 13 bearing two acyl fragments at oxygen atoms of pyranone and pyrazole

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• achieved due to chemical modification of ANTH [25][32]. Changes in the UV–vis spectra were typically used as an indication of the compounds’ decomposition. It is well established that ANTH is rapidly oxidized to form anthraquinone upon exposure to light in the presence of oxygen. Furthermore, endoperoxides

• were shown to form from ANTH(RF)n derivatives within minutes at room temperature in the presence of oxygen when irradiated with a high pressure mercury lamp [32]. When 9,10-bis(perfluorooctyl)anthracene was dissolved in CHCl3 and irradiated for 350 minutes, photodecomposition was observed. However, the

• use of fluorous solvents was shown to dramatically improve its photostability [25]. We performed a comparative study of the photostability of ANTH and 9,10-ANTH(BnF)2 dissolved in CH2Cl2. The absorbance was measured over 53 days in the presence of oxygen, as shown in Figure 3. Both samples were

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

• ). Overall, it was concluded that 7.1 and 7.2 first react to give 7.4 via a dark mechanochemical thiol–yne reaction; the latter is then converted to 7.3 by singlet oxygen generated in situ, by eosin Y. It is important to notice here that the reaction is proposed to proceed according to a different

• insoluble reagents and/or photocatalysts. Additionally, as discussed, the use of impact forces can lead to unique selectivity profiles compared to solution-based methods, further enhancing its utility. Thirdly, dissolved oxygen must be often meticulously removed in solution-based methods via tedious

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

• diaryl λ3-bromanes under remarkably mild conditions with subsequent applications of the in situ-generated arynes in cycloaddition reactions [3], meta-selective reactions with oxygen and nitrogen nucleophiles [4][5], regiodivergent meta or ortho-alkynylations [6], and regioselective (di)halogenation [7

Identification and removal of a cryptic impurity in pomalidomide-PEG based PROTAC

• Bingnan Wang,
• Yong Lu and
• Chuo Chen

Beilstein J. Org. Chem. 2025, 21, 407–411, doi:10.3762/bjoc.21.28

• addition intermediate is stabilized by an oxygen atom only. As such, the erosion of 3 by taurine was minimal. Conclusion Nucleophilic aromatic substitution of 4-fluorothalidomide (1) has provided a convenient entry to the IMiD class of PROTAC molecules. Although the yield of the desired product is

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• , Scheme 18) gave product 108 with higher 1,2-cis selectivity. In protocol A, the tosylamide forms an intramolecular hydrogen bonding with the benzylic oxygen forming a quasi-bicyclic intermediate acting as a 1,2-trans directing protecting group. Thus, following subsequent formation of the oxocarbenium ion

• 104, neighbouring group participation is exhibited by the sulphonamide oxygen thereby giving complete 1,2-trans stereoselectivity by facilitating the attack of the acceptor molecule from the non-hindered β-face of the sugar ring. However, in protocol B, the use of participating solvents like ether

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• oxygen atom [50]. Preferential N-alkylation (over O-alkylation) of 1,2-benzothiazine scaffolds has also been carried out by Ahmad and co-workers in 2014 and Szczęśniak-Sięga and companions in 2018 [37][51]. Structure elucidation of all the synthesized derivatives was carried out using 1H, 13C NMR, and

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

• suppress side reactions. The cross-dehydrogenative coupling reactions, under near-infrared irradiation, was found to proceed via an energy-transfer mechanism involving singlet oxygen generation rather than the typical electron-transfer pathway observed in the presented visible-light-mediated reactions in

• this review hitherto. This singlet oxygen is generated by the energy transfer from the excited state of the phthalocyanin zinc complexes to molecular oxygen, allowing the oxidation of the N-phenyltetrahydroisoquinoline 21 into a reactive iminium intermediate that subsequently couples with nucleophiles

• light (λ = 750 nm), followed by triplet energy transfer to molecular oxygen, generating singlet oxygen as the active species. Similarly as in the case of the Furuyama et al. study, the singlet oxygen subsequently oxidizes the amine substrate to an iminium ion, which reacts with a cyanide nucleophile to

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

• pentacenes, are relatively stable molecules under ambient conditions, longer acenes undergo spontaneous dimerization and react with oxygen [5][6], owing to the rising diradical character. This behavior was also observed in the oxidized species of shorter acenes [7]. Surprisingly, Bettinger and Einholz [5

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

• catalysts in conjunction with oxygen [17][18][19][20][21][22], electrochemical oxidation [23][24], and photochemical oxidation techniques [25] have emerged as alternative methods. However, these approaches have a significant limitation: the substrates must be thiols, which have unpleasant odors. This has

• produce oxygen and HI. Conclusion In summary, we have developed a new TBAI-catalyzed method for the synthesis of symmetrical disulfides using sodium sulfinates as starting materials. The method requires no additional redox reagents and is broadly applicable to both sodium arylsulfinates and sodium

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• region of the DNA double helix, leading to the formation of a reversible covalent bond [9][10][11][12]. In this process, the oxygen functional groups at the C8 and C18 positions of the core scaffold interact with the DNA bases through multipoint hydrogen bonds (HBs), allowing recognition of approximately

• avenues for the development of fluorescent probes based on the bis-THIQ alkaloidal scaffold. Further efforts to develop a concise and modular synthetic process for saframycins are currently underway. Representative bis-tetrahydroisoquinoline (THIQ) alkaloids and their analogues. Oxygen atoms on both the A

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• oxygen, nitrogen, or sulfur, and a positively charged hydrogen atom, which interacts with a lone pair on the acceptor. Apart from these common heteroatom-containing hydrogen bond donors, certain carbon–hydrogen moieties can also act in this way, although in a substantially weaker capacity [5][6][7][8][9

• oxygen lone pairs (LPs) of Me3PO with the H–CF2Ar antibonding orbital (σ*). Such hyperconjugative interactions indicate the magnitudes of the charge transfer from the LPs to the σ* orbitals and are considered the major contributors to hydrogen bonding [57]. Using this analysis, strong linear correlations

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• amide macrocycle with six aromatic residues (hereafter called cyclo[6]aramide for brevity, Scheme 1a) could mediate dimerization as a host. That is because such a 2D macrocycle has six carbonyl oxygen atoms pointing inwards as binding sites, demonstrating excellent affinity for cationic organic guests

• -ray structure of the complex H2 ⊃ G1. a) Dimeric structure formed by cyclo[6]aramide H2 and cationic guest G1, with each guest molecule threading one molecule of H2 at its end. b) A portion of the dimeric structure showing an array of hydrogen bonding interactions between the amide oxygen atoms of H2