Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• in this HIM system, the 1H NMR titration data was used to determine the association constants for metal coordination. Two stock solutions were prepared with one containing a concentration of 2.83 mM of the macrocycle (HIM) in a mixture of deuterated chloroform and acetone 1:2. The second stock

• solution contained the metal BArF20 or BArF24 at a concentration of 10 times that of the HIM concentration. Gradually adding the metal BArF20 or BArF24 stock solution to the HIM stock solution in an NMR tube allowed the host-to-guest ratio to be varied while keeping the host concentration constant. With

• fluctuation of the concentration of the host and the guest, which contribute to the x-axis in the fitting process. The isothermal fitting to 2:1 models is often prone to overfitting with NMR data and is noticeable with the fit for 1. However, the general trend does correlate with the strength of the

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

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• , tetrabutylammonium iodide (TBAI), and water significantly accelerated aryne generation, thereby increasing its local concentration. This favored aryne coordination to the palladium center, followed by CO insertion and reductive elimination to furnish phenanthridinones. In contrast, when dppm was introduced

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

• drug dexamethasone (IC50 = 13.25 ± 1.39 µM). At a concentration of 100 µM, the NO inhibition of pyrrolidine-2,3-dione derivatives 5a, 5b, and 5e was 53.65%, 50.22%, and 63.65%, respectively, as compared to 85.04% of dexamethasone. It is clear that the presence of a nitro group or halogen atom on the

• benzene ring at the 5-position of pyrrolidine-2,3-dione core in compounds 5c and 5d could relate to the lower inhibitory activity of 23.76% and 38.41% at the concentration of 100 µM, respectively, as compared to 5a and 5b. However, the existence of a nitro group on the aromatic ring attached to the 1

• -position of that heterocyclic core in compound 5e resulted in a dramatic increase in the NO inhibitory capability. More importantly, all studied compounds 5a–e did not show cytotoxicity to macrophage cells; 90.35–95.74% cells survived at the concentration of 100 µM of 5a–e (Table S3 in Supporting

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

• concentration, with a decrease in efficiency observed at lower concentrations. The reaction proceeded well under nitrogen, indicating that the oxidation process is unrelated to the presence or absence of oxygen. The yields of some products are likely due to the strong electron-withdrawing effects of the

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• . Supporting Information File 1, Figures S13–S16). DMSO is known for its bactericidal effect and still, the use of this organic solvent in bioassays is common [42]. In general, a DMSO concentration of less than 10% (v/v) is accepted as nontoxic [43]. In any case, the effect of DMSO in the assays was carefully

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• concentrations of the reaction mixture were: 2.5 µM RNA, 50 µM ligand, 50 mM HEPES, 100 mM KCl and 2.0 mM MgCl2. After incubation (37 °C, 5 hours), the reaction was quenched by adding 40 µL of a Na2H2EDTA solution (200 mM) to reach a final concentration of 80 mM Na2H2EDTA in a volume of 100 µL. Each sample was

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• temperature overnight. Afterwards, the mixture was centrifuged (4400 rpm, 10 min) to pellet excess insoluble C1. An aliquot of the supernatant and a solution of dimethyl malonic acid as a non-binding internal standard of known concentration were transferred to an NMR tube followed by collection of a 1H NMR

• monitored the chemical shift of Ha (Supporting Information File 1, Figure S14). Over this dilution range, the resonance for Ha remains a sharp singlet at 6.94 ppm. Accordingly, we conclude that C1 remains monomeric at the low concentration (100 μM) typically employed for isothermal titration calorimetry

• achieved by changing the concentration of host in the ITC cell [76][77][78]. Figure 7a presents the thermogram recorded when a solution of C1 (100 μM) in phosphate-buffered saline (PBS) in the ITC cell was titrated with a solution of CHDA (1 mM) from the ITC injection syringe. The DP versus time data in

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• fluorinated alkyl iodide precursor 10, the corresponding alkylation reaction with the Ni(II) complex 1 was conducted under previously optimized conditions for the synthesis of Fmoc-TfIle [13] in terms of base (NaH) and solvent (DMF) and thoroughly screened in terms of base equivalents, concentration and

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

• observed (see Supporting Information File 1, page S3). Decrease in supporting electrolyte concentration led to a drop in yields (Table 1, entry 9 vs entry 8), whereas current density deviations from 12 mA/cm2 did not affect the outcome of 6a (see Supporting Information File 1, page S4). Interestingly

• (0.1 M, electrochemical grade) was employed as the supporting electrolyte in 5:1 MeCN/H2O solution. The electrolyte was purged with argon for at least 3 min prior to recording. Compounds 6a and 9a were analyzed at a concentration of 3 mM or 6 mM and at a scan rate of 100 mV s−1. The peak potential Ep

• mM concentration, respectively, in 5:1 MeCN/H2O (0.1 M Et4N–BF4). B) Anodic oxidation of pyrrolidine 6a. Plausible mechanism for formation of pyrrolidine 6a and hemiaminal 10a. Preparation of malonic acid monoester 9a. Electrolysis of acid 9d in deuterated solvents. Scope of the decarboxylative

Semisynthetic derivatives of massarilactone D with cytotoxic and nematicidal activities

• Rémy B. Teponno,
• Sara R. Noumeur and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 607–615, doi:10.3762/bjoc.21.48

• added to 120 µL aliquots of a cell suspension (5 × 104 cells/mL) in 96-well microplates. After 5 days incubation, an MTT assay was performed, and the absorbance measured at 590 nm using an ELISA plate reader (Victor). The concentration at which the growth of cells was inhibited to 50% of the control

• (100, 50, 25 and 12.5 μg/mL). Ivermectin was used as a positive control at the same concentration ranges as the tested compounds and MeOH was used as a negative control. Percentages of mortality were calculated, then the results were expressed as a LD90 and LD50. Preparation of massarilactone D

Asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon centers by halogen-bonding catalysis with chiral halonium salt

• Yasushi Yoshida,
• Maho Aono,
• Takashi Mino and
• Masami Sakamoto

Beilstein J. Org. Chem. 2025, 21, 547–555, doi:10.3762/bjoc.21.43

• chiral halonium salt. Next, the reaction temperature was optimized, and −40 °C was found to be optimal (Table 1, entries 7–9). Further optimization of the reaction conditions (amounts of potassium carbonate and pre-nucleophile, catalyst loading, and concentration) were conducted, and the reaction with

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

• – a chemoselective receptor for aromatic amino acid esters in water. Fluorescence emission spectra of receptor 1 (25 μM in H2O) upon addition of increasing amounts of tripeptide 2. The concentration of the guest corresponding to each curve is indicated on the right. The arrow marks the quenching of

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

• photoproducts were insoluble resulting in decreased concentration of 9,10-ANTH(BnF)2 in the irradiated solution or new photoproducts had similar absorption features. To identify the photoproducts in the irradiated solutions of ANTH and 9,10-ANTH(BnF)2, complementary NMR analyses were carried out (Figures S6 and

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• fluorescence spectra are presented in Supporting Information File 1 (Figures S12–S14). For the fluorescence quantum yield measurements, solutions of each bimane were prepared, and the concentration was adjusted so that the absorbance at the right shoulder of the band at 360 nm falls within the range of 0.03

• using UV–vis spectroscopy, where the concentration was adjusted such that the absorbance is 2.164 at the λmax. The solution was added into a quartz fluorescence cuvette, and irradiated for 15 minutes at a time using the same 405 nm LEDs in a turntable chamber. Structures of a) the unfunctionalized

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• neurotransmitters [10][11] or as switching units for potential dependent potassium channels [12]. Compared to the Z → E conversion rate of 92% (in n-hexane) of the parent diazocine the conversion in water/DMSO mixtures is decreasing with increasing water concentration (73% in water/DMSO 9:1) [8][9][10][11][12

Synthesis of electrophile-tethered preQ₁ analogs for covalent attachment to preQ₁ RNA

• Laurin Flemmich and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 483–489, doi:10.3762/bjoc.21.35

• . PreQ1 riboswitches sense the cellular concentration of preQ1 and regulate the expression of downstream located genes associated with the biosynthesis or transport of Q in a feedback-like manner. Binding of PreQ1 to the mRNA causes the riboswitch to commit an altered folding pathway, which affects the

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• the kinetic resolution at a concentration of approximately ten millimolar (mM) to prevent the Michael retro-Michael equilibrium from affecting the process. Keywords: 1,5-dicarbonyl; equilibrium; kinetic resolution; organocatalysis; retro-Michael; Introduction For many years, enantiomers have been

• promotes the Michael reaction, leading to the formation of the enantiomer (3R,4S) and consequently returning to the racemate. Then, we decided to investigate how concentration affects the rate and selectivity of the reaction at room temperature (Table 4). The retro-Michael reaction mainly occurs at a

• concentration of 0.17 M, producing a nearly racemic mixture of anti-1 (entries 1 and 2, Table 4). Lowering the concentration to 0.10 M slows the reaction and improves the enantiomeric ratio (entries 3 and 4, Table 4), but a nearly racemic mixture is obtained again with longer reaction times (entry 5, Table 4

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

• turn demands large volumes of solvents, negatively impacting the sustainability of light-mediated synthesis as it transitions from academic curiosity to industrial application. Moreover, since the solvent is the reaction component with the highest concentration, competitive side-reactions such as

• mechanochemistry holds potential for unique opportunities for substrate activation while adopting an environmentally benign emerging technology (Figure 2, top). For example, it is well known that molecules in the solid state (or in very high concentration) often exhibit photophysical behaviors distinct from those

• working at this interface have the potential to redefine the landscape of sustainable synthesis, with this Perspective serving as a snapshot of the current state-of-the-art. The Grotthuss–Draper, Einstein–Stark, and Beer–Lambert laws. T: transmittance; ε: molar attenuation coefficient; c: concentration; l

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

• water (Figure 2A) [71][72][73], or by binding a hydrophobic substrate and holding it close to a functional(ized) rim (e.g., as in cyclodextrins) that performs a reaction (Figure 2B) [74][75][76][77][78][79]. These effects are driven mostly by effective concentration/molarity (i.e., proximity of reacting

• concentration. As for the macrocycles discussed above, dual confinement/encapsulation [36] and the hydrophobic effect dominate the origin of catalytic rate enhancements [158][159]. To avoid product inhibition, model reactions that increase molecularity (A → B + C) or that generate weakly interacting or less

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

• reaction was concentration dependent, giving various amounts of 6 under otherwise the same reaction conditions. For example, at 10–30 mM wherein most of the pilot studies were conducted, the ratio of 3 and 6 could be as low as ≈1:50 by 1H NMR and ≈1:10 by MS analysis. Under these conditions, the formation

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

• idea of glycosylation mechanisms to enable the readers to have a background idea as a reference before going to describe the role of protecting groups. The mechanistic pathway of glycosylation strongly depends on many factors, especially, the concentration of the participating moieties, the reaction

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• possibility of carrying out subsequent stages of research and selecting promising compounds for the further development of anticancer drugs [30]. The study showed that the IC50 inhibitory concentration of 2-(1,1-dimethyl-1H-benzo[e]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone (7a) against the A431 skin cancer

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

• inhibitory concentration, MIC90) values for compounds 7b and 7h against three different strains of Staphylococcus aureus: susceptible (ATCC 25923), methicillin-resistant (ATCC BAA-41), and multidrug-resistant (ATCC BAA-44). Table 2 shows the MIC90 values for the two halogenated compounds against different

• acetonitrile was added dropwise. Then, the reaction mixture was continued to reflux for 24 h or until the termination of the reaction. Reaction progress was monitored after intervals using TLC. On completion, filtration of the reaction mixture was performed followed by concentration under vacuum. It was then

• concentration under vacuum. It was then diluted with cold water and acidified with 5% cold HCl. The solution was allowed to stand for 15 minutes to complete precipitation. Precipitates were collected via filtration and washed with excess distilled water. The dried product was then recrystallized from absolute

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• screening assays were conducted to explore their antibiofilm properties. According to the crystal violet (CV) assay, both compounds exhibited significant activity in the S. aureus biofilm inhibition assay. Farinosone A (2) (Figure 5A) displayed activity at a concentration as low as 3.9 µg/mL, resulting in

• approximately 68% inhibition of biofilm formation. Similarly, farinosone D (1) demonstrated activity up to a concentration of 15.62 µg/mL, achieving a comparable inhibitory effect of approximately 74% at this dilution. In addition, only farinosone A (2) (Figure 5B) demonstrated moderate activity in the

• preformed biofilm assay, dispersing a 24 hour preformed biofilm up to a concentration of 15.62 µg/mL with an eradication capacity of 43%. To evaluate whether the remaining biofilm biomass in the wells was metabolically active or not, a cell viability (XTT) assay was conducted after 24 hour treatment of S