Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• inconsistency made it challenging to rely on NMR as the primary method for confirming the structure of the expected products. To overcome this limitation, other analytical techniques, such as mass spectrometry and infrared (IR) spectroscopy, were employed. These methods successfully corroborated the formation

• quantitatively using UV–vis absorption spectroscopy. At acidic pH, only broad absorption bands at 370 nm and 325 nm were detected for compounds 3n and 4n, respectively. These results can be attributed to a phototautomerism effect in both the ground and excited states [97]. Additionally, fluorescence spectra

Efficient solid-phase synthesis and structural characterization of segetalins A–H, J and K

• Liangyu Liu,
• Wanqiu Lu,
• Quanping Guo and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2025, 21, 2612–2617, doi:10.3762/bjoc.21.202

• purification, all cyclopeptides were obtained in 45–70% isolated yields. Structural identities were confirmed by HRESIMS, NMR, and HPLC (>95% purity). Circular dichroism (CD) spectroscopy revealed distinct secondary structures, including β-sheets (1, 2, 3, 4, 7, 8, 10) and α-helical elements (5, 6). This

• . Secondary structure analysis by circular dichroism (CD) The secondary structures of compounds 1–10 were investigated using circular dichroism (CD) spectroscopy in aqueous buffer (0.01×PBS), deionized H₂O, and 30% TFE (2,2,2-trifluoroethanol) (Figure 2). CD spectra in the far-UV region (190–250 nm) provide

• –220 nm and a maximum below 200 nm. CD spectroscopy revealed that cyclic topology shifts characteristic peaks and stabilizes secondary structures through cooperative ring size/sequence/solvent effects [30]. TFE disrupts the hydrogen-bonding network of water, reduces solvent polarity, and enhances the

Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water

• Michaela Šusterová and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201

• characterized by FTIR spectroscopy (Supporting Information File 1, Figure S1). In comparison to crude silica gel, the diminished band corresponding to the –OH group (around 980 cm−1) and the appearance of new bands characteristic of amino groups (around 3000 cm−1) indicate the successful introduction of amino

• in the same way. After the treatment of the SG-NHCO-BU1 material with 1 M KOH, the supernatant was analyzed in the presence of 1 mM dicyanoaurate by UV–vis spectroscopy (Figure 1C). The measured spectra were identical with the spectrum of pure dicyanoaurate solution revealing that SG-NHCO-BU1 did not

• gel modified either with covalently or noncovalently immobilized BU1 was further investigated for its ability to sorb anions from water and in terms of recyclability. For this purpose, dicyanoaurate ([Au(CN)2]−) was selected as this anion can be monitored by UV–vis spectroscopy (Figure 2) and plays a

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• 19 was moderate because the anomeric carbon at C7 is associated with an acid-sensitive acetonide group. The structural determination of the major product 19a was accomplished by comprehensive NMR spectroscopy and further unambiguously confirmed by X-ray analysis (see Supporting Information File 1 for

Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles

• Kaylen D. Lathrum,
• Emily M. Hanneken,
• Katelyn R. Grzelak and
• James T. Fletcher

Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194

• observed for these annulated molecules, while their analogous non-annulated control compounds were not bioactive. Keywords: annulation; arenes; antimicrobials; fused-ring systems; UV–vis spectroscopy; Introduction Polycyclic aromatic heterocycles are a diverse class of small molecules with utility in a

• the NMR timescale. These trends were observed similarly for the other analogs of this study (see Supporting Information File 1). Optoelectronic properties of each annulated product and its respective control compound were examined via UV–visible absorption and emission spectroscopy. Figure 6 shows the

• isoquinoline subunits. Heterocycle subunit identity and triazole C/N connectivity influenced the annulation reaction efficiency. Aromatic π-system expansion resulting from annulation was characterized by NMR, absorption and emission spectroscopy. Five benzotriazolophenanthroline regioisomers sharing structural

Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• membrane composition on azobenzene photoswitching We investigated the photoisomerization behavior of rotaxane 1 (Figure 2) over ten irradiation cycles in large unilamellar vesicles (LUVs) with varying lipid compositions using UV–vis spectroscopy. Specifically, we prepared vesicles composed of pure EYPC

• the bilayer. This enables us to investigate how the switching of azobenzene units affects the hydrophobic core of the bilayer. We confirmed the efficient photoisomerization and photoreversibility of rotaxane 4 in solution over 20 cycles using UV–vis spectroscopy (Supporting Information File 1, Figure

• multiple membrane environments, including LUVs composed of EYPC, EYPC/Chol mixtures, and DPPC. UV–vis spectroscopy confirmed robust photoswitching over ten irradiation cycles with minimal fatigue, independent of bilayer composition. However, the membrane's physical properties strongly influenced the

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• thiophene, promoting further study of these structures and reaction mechanism. 1H NMR spectroscopy of the obtained mixture provided the first key information about its nature, namely the presence of two major products 2 and 3, both of which showed three characteristic singlets with signal integration 1:3:3

• Analytical studies were carried out using equipment of the Center for Joint Use «Spectroscopy and Analysis of Organic Compounds» at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences. Funding This study was supported by the Russian Science Foundation, Grant No

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• thoroughly characterized by 1H and 13C NMR spectroscopy, HRMS, and single-crystal X-ray diffraction analysis (Figure 1). A range of solvents was subsequently screened; however, none provided an improvement over 1,4-dioxane for this transformation (Table 1, entries 2 and 3). In addition to AgNO3, other silver

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• determined by 1H NMR spectroscopy. (A) Conformers arising during the rotation around the C5–C6 bond in pyranosides. (B) Furanoside ring conformers of monosaccharide 2 in the pseudorotation diagram. The dashed colored circles denote the initial conformations taken for optimization. Solid colored circles

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• on the recovery of solvents utilized in the aforementioned reaction (Figure 11). In addition, the completion of the cycloaddition reaction can be readily monitored through the utilization of Fourier-transform infrared (FTIR) spectroscopy and/or thin-layer chromatography (TLC) analysis (Figure 12). In

• properties of the solvent, which must facilitate practical isolation of the product at the end of the process [124]. As previously stated, the process of following the cycloaddition reactions within the scope of this study by means of FTIR spectroscopy is a relatively simple and practical task. The data

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• ) and WDG (rigid fluorene backbone), were synthesized via Friedel–Crafts reactions. Their iodide (I−) recognition properties were systematically explored using 1H NMR, UV–vis absorption, and fluorescence spectroscopy. Quantitative analysis via the Benesi–Hildebrand equation and nonlinear fitting

• rotationally restricted, all its accessible conformations constitute a subset of PBG's conformations. The binding constants and conformational change mechanisms of the two analogs were quantitatively evaluated by proton nuclear magnetic resonance spectroscopy (1H NMR), ultraviolet–visible absorption

• spectroscopy and fluorescence spectroscopy, combined with Benesi–Hildebrand equation [23] and nonlinear curve fitting [24]. The purpose of systematically exploring the difference between the two types of recognition of I− is to reveal the regulation law of conformational dynamics on the binding mechanism

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• , rhodamine 6G, methyl violet 6B; 7500 rpm, 5 min for acridine orange and methylene violet), and the supernatants were analyzed by UV–vis spectroscopy. To determine the dye concentration remaining in the aqueous solutions, appropriate calibration curves were employed (Figure S12 in Supporting Information File

• , for 1 hour at 25 °C using a ThermoMixer™. The samples were centrifuged, and the supernatants were analyzed by UV–vis spectroscopy. The removal efficiency for each experiment was calculated by using Equation 1. Figure 7a,b shows a plot of removal efficiency versus the quantity of H2 or G2W1 used. The

• the supernatants were analyzed by UV–vis spectroscopy. The removal efficiency values were calculated using Equation 1 and the results are shown in Figure 8. Figure 8 shows that the removal efficiency increases as the initial dye concentration increases. Specifically, we see that at [methylene blue

Halogenated butyrolactones from the biomass-derived synthon levoglucosenone

• Johannes Puschnig,
• Martyn Jevric and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175

• fluorination attempts. Maintaining some residual solvent allowed for the characterization of compound 13 by NMR spectroscopy. Stereochemical assignment in 13 was based on a large trans-axial coupling constant JH2exo-H3 = 10.6 Hz in the 1H NMR spectrum and interactions between H3endo and H7endo on the

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• ]. However, its use in the analysis of chiral amines has been restricted, largely due to the complexity arising from their conformational flexibility [3]. Circular dichroism (CD) spectroscopy offers a highly sensitive technique for stereochemical analysis at the microgram scale [4][5][6]. In particular

Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid

• Yana I. Sakhno,
• Oleksander V. Buravov,
• Kostyantyn Yu. Yurkov,
• Anastasia Yu. Andryushchenko,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158

• control of the reaction, while oxygen-bridged heterocycles 4 are formed under thermodynamic control. The purity and structure of compounds 4 and 5 were established by elemental analysis, mass spectrometry, 1H and 13C NMR spectroscopy, and X-ray diffraction study (Figure 1). For example, the 1H NMR spectra

α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• and 13C NMR spectroscopy, and by X-ray diffraction study (see Experimental part). The 1H NMR spectra of compounds 5 are characterized by the following signals: a broad carboxyl group proton singlet at 12.10–12.17 ppm, an NH group proton singlet at 7.74–8.02 ppm, an aromatic protons multiplet at 6.52

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• and 1.2 equiv 2,6-(t-Bu)2Py in EtOAc gave the styryl side chain-containing tetrahydrofuran 8a with 82% NMR yield after 3 h at 60 °C (Table 3, entry 2). The formed double-bond geometry in product 8a was proved by the 2D-NOESY spectrum. The corresponding (Z)-isomer was not detected by NMR spectroscopy

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• spectroscopy. As shown in Figure 2, complete consumption of 1 was observed under these conditions with concomitant formation of a major new species with a characteristic 1H NMR signal at δ = 4.42 ppm (in CDCl3, Table 1, entry 1). Comparison of the spectrum with that of an authentic sample (see Supporting

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• yields (ΦF up to 0.69). Furthermore, enantiomeric resolution of inherent chiral MC1 was achieved using preparative chiral HPLC, enabling detailed investigation of its chiroptical behavior through circular dichroism and circularly polarized luminescence spectroscopy. Keywords: dihydroindolocarbazole

• through circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy. Results and Discussion The syntheses of N-doped macrocycles MC1–3 are shown in Scheme 1. Diamines 1a and 1b were synthesized by double Pd-catalyzed C–N coupling reaction of 4,6-dichlorobenzene-1,3-diamine with phenyl

• characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Single crystals suitable for X-ray diffraction measurements of compounds 3a, MC2, and MC3 were successfully obtained to reveal their molecular structures. In the crystal structure of 3a (Figure 2a), the two pyrene units are nearly

Synthesis, biological and electrochemical evaluation of glycidyl esters of phosphorus acids as potential anticancer drugs

• Almaz A. Zagidullin,
• Emil R. Bulatov,
• Mikhail N. Khrizanforov,
• Damir R. Davletshin,
• Elvina M. Gilyazova,
• Ivan A. Strelkov and
• Vasily A. Miluykov

Beilstein J. Org. Chem. 2025, 21, 1909–1916, doi:10.3762/bjoc.21.148

• as thick liquids with good yields (44–67%) and purity. The structures of glycidyl esters of phosphorus acids 1–3 were confirmed by 31P, 1H NMR, IR spectroscopy, and elemental analysis (see Experimental part for additional information). The 31P{1H} NMR spectrum of diglycidyl methylphosphonate (1

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• extracted three times with CH2Cl2. The combined organic layers were dried over Na2SO4, filtered and concentrated under vacuum. Yields were calculated on the reaction crude by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. In the case of the large-scale reaction the crude was

• /cm2), total charge 2.2 F/mol, dry DMF (0.125 M). Yields reported are isolated yields. Reactions were performed on a 0.5 mmol scale. Continuous flow synthesis of piperazine 2a. The yield was determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. Reactions were performed

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• leaving group and activated, electron-poor dipolarophiles has been reported [31][32]. Treatment of aldehyde 4 with hydroxylamine in toluene at 60 °C for 1–3 h resulted in loss of the aldehyde as judged by 1H NMR spectroscopy of the crude mixture. When this was carried out in the presence of N

• -methylmaleimide with the mixture being heated under reflux for 3–4 h, we were pleased to obtain the spirooxindole product 5, which was formed as a mixture of stereoisomers (Scheme 3). The ratio of isomers was determined by 1H NMR spectroscopy and the major isomer could be isolated after careful column

• fumarate was also successful and gave a mixture of the stereoisomeric cycloadducts 7 (Scheme 5). The yield was high and three inseparable stereoisomers could be detected by 1H NMR spectroscopy. In each case we assume that the methyl ester groups are trans to one another due to the expected concerted nature

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• respective isocyanate in acetonitrile at 80 °C; KSU-1 reacted with isopropyl, tert-butyl, n-hexyl, and tetradecyl isocyanate to generate KSU-1iPr and KSU-1t-Bu, KSU-1n-Hex, and KSU-1C14, respectively. Successful post synthetic reaction was observed by proton nuclear magnetic resonance (1H NMR) spectroscopy

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• presence of H-bond acceptors [102][104][107]. The presence and the nature of the H-bond can be identified by 1H NMR spectroscopy since the N–H proton has a characteristic chemical shift depending on the H-bond acceptor [101]. Arylhydrazones based on pyridine have been intensively studied since the H-bond

Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp²)–C(sp²) bond scission of styrenes

• Prafull A. Jagtap,
• Manish M. Petkar,
• Vaishnavi R. Sawant and
• Bhalchandra M. Bhanage

Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142

• -disubstituted quinolone 3a along with 36% of 4-substituted quinolone 3a′ were observed during GC and GC–MS analysis, and the structures of both quinoline moieties were identified by 1H and 13C NMR spectroscopy. Encouraged by this result, we next examined the feasibility of the reaction with methanol as solvent