Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins

• Juliana V. Petrova,
• Varvara T. Tkachenko,
• Victor A. Tafeenko,
• Anna S. Pestretsova,
• Vadim S. Pokrovsky,
• Maxim E. Kukushkin and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118

• ]. The most dramatic discrepancy in spiro-compound yields was observed during the reaction with this nitrile oxide, suggesting that classical conditions (low temperature and inert atmosphere) may prove more fruitful in preventing the degradation of the dipole. The influence of the concentration of the

• 96-well culture plates at a concentration of 4–7 × 103 cells/mL and incubated at 37 °C for 24 hours. The cells were counted after treatment with trypan blue solution (0.4%) in a Goryaev chamber. Then, after incubation at 37 °C for 72 h, the cells were exposed to various concentrations of the studied

Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent Cyrene^TM under one-pot conditions

• Zoltán Medgyesi and
• László T. Mika

Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117

• of volatile compounds from the aqueous phase by vacuum distillation, 88% of CyreneTM (13.7 g) was recovered. The reaction was repeated four times with the same procedure under identical conditions (same catalyst and substrate concentration). It was shown that CyreneTM could be successfully recovered

General method for the synthesis of enaminones via photocatalysis

• Paula Pérez-Ramos,
• Raquel G. Soengas and
• Humberto Rodríguez-Solla

Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116

• , the rate of the reaction is independent of the concentration of the 3-bromochromone substrate 7a and amine 8a (Figure S4, Supporting Information File 1). Based on the above experiments and prior work on the photocatalytic reductive halogenation using acridinium photocatalysts [45][46], a possible

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• change from pale yellow to bright red. Since the protonated 3 shows minimal absorption between 300–400 nm (Figure 1B), the degree of protonation can be estimated by comparing the absorbance at 358 nm (neutral) and 502 nm (protonated). As the degree of protonation and initial concentration are known, the

• determined using Equation 2. If the stoichiometry is correct, the calculated ∆G° values should not depend on the initial acid concentration. We considered options where 3 forms ion pairs with one, two or three MSA molecules in DCE. The ∆G° values were calculated at three temperatures (15, 25, and 50 °C) for

• nine acid concentrations ([MSA]0 = 154–3080 µM, or 10–200 ppm; see Tables S1–S9 in Supporting Information File 1). For one or three acid molecules (n = 1 or 3), the ∆G° values varied with the initial acid concentration, indicating incorrect stoichiometry. However, for n = 2, constant ∆G° values were

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• by MTT assay and expressed as CC50 parameter (50% cytotoxic concentration) [32]. All results are gathered in Table 2. In general, the tested compounds did not demonstrate high levels of toxicity towards the investigated non-cancer cell lines. Among them, Vero cells showed the highest sensitivity

• (for synthesis of 4b,c, and 4e, see ref. [15]). The solution of diazomethane (CH2N2) in pentane was prepared without distillation and determination of the concentration following a procedure described in an earlier publication [28]. Preparation of 2c as a new precursor of thiocarbonyl S-methanide 1c

Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions

• Himani Malik,
• Sudha Devi,
• Debapriya Gupta,
• Ankit Kumar Gaur,
• Sugumar Venkataramani and
• Thiruvancheril G. Gopakumar

Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112

• accommodate ≈200 Tbits in a 1 cm2 area. Experimental Preparation of adlayer The FNAAP molecule is synthesized as per our previous report [29]. Ultra-thin films were prepared by drop casting from ethanolic solutions of molecules (concentration between 10−5 to 10−6 M) on freshly cleaved highly oriented

Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides

• Nadezhda M. Metalnikova,
• Nikita S. Antonkin,
• Tuan K. Nguyen,
• Natalia S. Soldatova,
• Alexander V. Nyuchev,
• Mikhail A. Kinzhalov and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110

• photochemical reactions such as the reagents concentrations and ratio. Surprisingly, both dilution of the reaction mixture to 0.05 M and concentration to 0.2 M led to reduced yields (Table 1, entries 12 and 13) compared to the optimal concentration of 0.1 M. Furthermore, the yield of 2aa exhibited minimal

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• crystal was used and the samples were scanned 128 times. The UV–vis spectra were measured on a Jasco V-570 UV–vis–NIR spectrophotometer using spectral grade solvents in the concentration range ≈10−5 mol/L. The steady-state fluorescence spectra were recorded with a FluoroLog 3-22 (HORIBA

N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B

• Joy E. Rajakulendran,
• Emmanuel Tope Oluwabusola,
• Michela Cerone,
• Terry K. Smith,
• Olusoji O. Adebisi,
• Adefolalu Adedotun,
• Gagan Preet,
• Sylvia Soldatou,
• Hai Deng,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103

• show modest activity against L. major. All the remaining compounds (1–3 and 5–7) tested in this assay showed no activity at the highest concentration very likely due to the free carboxylic acid moiety present in some compounds (1, 3 and 7), prevent uptake into the parasites. This could also explain the

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

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

• regioselective functionalization at the periphery of the PAHs. Besides triflyloxylation (42, 43), the introduction of one or two dichlorovinylene groups (43, 44) was observed. As in previous cases, the exact ratio of the products depended on the amount of DDQ and concentration of the precursor. Analysis of NICS

Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents

• Julius Krenzer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97

• addition, since condensations are affected by the bimolecular addition as an elementary step, special attention to the concentration of the nucleophiles has to be paid. According to Mayr’s nucleophilicity scales [8][9][10], a nucleophilicity parameter N for the specific S,N-ketene acetal intermediate 4 can

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

• ) sulfate under an argon atmosphere afforded 3a in 33% yield. These results indicate, that copper(II) at high loading is capable of oxidizing H-phosphonate even in inert conditions [72]; however, a balanced concentration of oxygen in the reaction mixture is required for recycling of copper catalyst and

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• -PfATP4 activity would be required to definitively assess the tolerability of tertiary alkylamines at position 8. Whilst compounds 1, 2 and 4–12 showed no cytotoxicity against HEK293 cells at the top concentration tested (80 µM), for those compounds with concomitant antimalarial activity (1, 10–12), their

• . Meaningful selectivity indices for these compounds could, therefore, likewise not be calculated. Hence, the mean % growth inhibition (duplicate, n = 1) at the top concentration is indicated in Table 1. Conclusion A modified approach for amine substitution of 5-chloro-3-(4-chlorophenyl)-[1,2,4]triazolo[4,3-a

Gold extraction at the molecular level using α- and β-cyclodextrins

• Susana Santos Braga

Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89

• several methods, with highlight to gravity concentration (based on the higher density of gold), cyanidation, and mercury amalgam [15]. The gravity method is a simple and, from the viewpoint of the environment, relatively harmless process that works well as a stand-alone for high-density gold particles and

• networks to optimize the chemical parameters of the extraction. An optimal value of gold removal, lying between 98 and 98.9%, was found to occur with a contact time of 40 minutes, a concentration of α-CD of 11.61 g/L and KOH was added in enough quantity to raise the solution pH to 5 [47][48]. Complexes of

• , containing 0.6 mg of gold) were mixed for 30 minutes with increasing amounts of α-CD (concentrations ranging from 1–10% w/v) [49]. Extraction yields were shown to increase with concentration of α-CD. The highest concentration tested, 10%, afforded 19% yield in gold. Competitive extraction tests with gold and

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