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

• values ranging between 409–426 nm. In general, the solvatochromic effect of these compounds showed a blue shift in EtOAc, and a red shift in MeCN. The fluorescence emission spectra of these compounds revealed a strong blue to green fluorescence emission, with the maximum emission peaks varying from 535

• to 573 nm for compound 3n and from 479 to 524 nm for compound 4n. Therefore, the fluorescence emission spectra demonstrated a clear dependence on solvent polarity and the maximum emission wavelength λem. Thus, a red shift in the emission bands was observed in solvents with higher polarity, indicating

• observed, however, with an increase in fluorescence emission. Interestingly, in DMSO, a bathochromic effect was observed alongside a significant increase in fluorescence intensity. In aqueous medium, a pronounced red shift was verified, likely due to stabilization of the excited state by water molecules

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• is reductively quenched by arene 16, producing the corresponding aryl radical cation C and 3CzCIIPN•– (E1/2 red = +1.56 V vs SCE). PC•– then reduces the azolium ion A (E1/2 = −0.81 V vs SCE) to generate the ketyl radical B, thereby closing the photoredox catalysis cycle. 2-Methoxynaphthalene produced

• photocatalysts such as fluorescein, alizarin red S, rhodamine B, and eosin Y. Since photoexcited organophotocatalyst rhodamine 6G (Rh6G*) possesses a sufficiently positive reduction potential in its singlet excited state S1 (Ered* = +1.18 V vs SCE*). The reduced form of Rh6G•– subsequently reduces BrCCl3 to

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

• -connected ortho-bromobenzene subunit analogs failed under microwave irradiation but were successful using conventional thermal heating in yields of 31–65%. The expanded nature of the aromatic ring system following annulation was reflected by the downfield shifting of aromatic 1H NMR signals and the red

• general red-shifting of UV absorbance signals for the annulated pentacycles presented in Table 1 relative to their non-annulated counterparts, further indicating an aromatic π-system expansion upon annulation. Similar trends were observed for those compounds shown in Table 2 (Figure S1, Supporting

Isoorotamide-based peptide nucleic acid nucleobases with extended linkers aimed at distal base recognition of adenosine in double helical RNA

• Grant D. Walby,
• Brandon R. Tessier,
• Tristan L. Mabee,
• Jennah M. Hoke,
• Hallie M. Bleam,
• Angelina Giglio-Tos,
• Emily E. Harding,
• Vladislavs Baskevics,
• Martins Katkevics,
• Eriks Rozners and
• James A. MacKay

Beilstein J. Org. Chem. 2025, 21, 2513–2523, doi:10.3762/bjoc.21.193

• PNA oligomer with the N-(2-aminoethyl)glycine backbone (in red); (b) Representative monocyclic synthetic nucleobase triples through Hoogsteen hydrogen bonding (blue dashed lines). Watson–Crick hydrogen bonds are in red (dashed lines). Representative extended nucleobase triples through Hoogsteen

• hydrogen bonding (blue dashed lines). Watson–Crick hydrogen bonds are in red (dashed lines). Evolution of the strategy for U–A recognition. Isoorotamide-derived nucleobases for A–U recognition. Proposed isoorotamide distal binding (Db) nucleobases designed from the Io5 core. Hydrogen bonding donors to the

• linker are highlighted in red. Sequences for RNA hairpins and PNA ligands used for binding studies. Major-groove view of hydrogen-bonding interactions in the (A) Db1*U–A triplet, (B) Db2*U–A triplet, (C) Db2*C–G triplet, and (D) Db3*U–A triplet. Carbon, hydrogen, oxygen, and nitrogen are labelled in

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• free energies were calculated at the B3LYP-D3/def2-tzvp//B3LYP/6-31G(d) level in MeCN. b) Spin density of IN4 (isovalue = 0.004). c) IRC analysis of TS2 (red line) and bond-length changes of C19–C3 (yellow line) and C19–C12 (blue line) along IRC path. d) Mayer bond order changes of selected structures

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

• for the methyl β-ᴅ-galactoside (A) and its α-counterpart (B). Green and red arrows indicate stabilizing and destabilizing spatial interactions, respectively. (A) Supposed PIF-rearrangement of monosaccharide 3. (B) Furanoside ring conformers of monosaccharide 4 in the pseudorotation diagram. The dashed

Catalytic enantioselective synthesis of selenium-containing atropisomers via C–Se bond formations

• Qi-Sen Gao,
• Zheng-Wei Wei and
• Zhi-Min Chen

Beilstein J. Org. Chem. 2025, 21, 2447–2455, doi:10.3762/bjoc.21.186

• . Keywords: asymmetric catalysis; atropisomer; chiral selenium-containing compound; C–Se bond formation; Introduction Selenium is an essential trace element for human body [1]. It plays an important role in metabolism. In 1817, the Swedish chemist Berzelius found that red residual mud was attached to the

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

• solvents. Furthermore, the evidence suggests that the majority of these solvents is hazardous and their utilization is to be avoided. As demonstrated in Figure 8a, the color of the spheres of the customary proportional solvents employed in [3 + 2] cycloadditions is red or yellow, thereby substantiating the

• (RED). In the absence of any energy difference, the RED number is equivalent to 0. RED numbers that are less than 1 indicate high affinity, whilst RED numbers that are equal to or close to 1 represent a boundary circumstance. RED numbers that are progressively higher demonstrate increasingly lower

• affinities. Accordingly, when the values are substituted, It is evident that, given the RED value of approximately 0.876, which is less than 1, the nitrone is likely to dissolve in a methyl laurate solvent. Methyl laurate is a medium-sized molecule that exhibits a combination of polar and non-polar

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• cannot undergo the photocyclization reaction when the macrocycle is in the BAA site due to conformational restraint. This system was used to form water-soluble nanoparticles to investigate their biological applications. The obtained nanoparticles exhibited bright red photoluminescence and the ability to

• the naphthalimide. Specifically, red fluorescence was observed when the merocyanine formed, and green fluorescence when the spiropyran was generated. Notably, this rotaxane was employed for the detection of sulfite, where the addition of sulfite led to the deactivation of FRET. This occurs due to a

• Michael addition taking place at the active site (C=C−C=N+) in the merocyanine unit in the presence of sulfite ions, resulting in color changes from red to green. This work represents a substantial advancement in the development of rotaxane-based fluorescent probes, providing highly sensitive and

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• : reactive substrates exhibited λmax < 460 nm (yellow-orange), whereas unreactive ones showed λmax > 460 nm (dark red-purple). This suggests insufficient excitation energy for Norrish type-II hydrogen abstraction in the latter. Such chromophore-dependent reactivity provides critical insights for designing

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

• textile, leather, paint, plastic, cosmetics, pharmaceuticals, and food industries [4]. It has been estimated that about 7 × 106 tons of dyes (e.g., methylene blue, rhodamine B, methyl orange, Congo red, disperse violet 26, methyl red, crystal violet) are produced annually worldwide [5]. Many dyes are

• by UV–vis of the supernatant. Experiments were performed in triplicate (n = 3). Error bars represent the error propagation of uncertainty. Cross-eyed stereoview of: a) one molecule of G2W3 in the crystal, and b) the packing of G2W3 in the crystal. Color code: C, grey; H, white; N, blue; O, red; F

• , green; H-bonds, yellow-red striped. Cross-eyed stereoview of: a) a molecule of G2W1 in the crystal, b) the packing of G2W1 along the xz-diagonal in the crystal. Color code: C, grey; H, white; N, blue; O, red. a) Plot of removal efficiency of methylene blue (240 μM, 1 mL) from water after incubating with

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• both Figures, beside the selective 1D NOESY spectrum (upper part in Figure 2 and Figure 3), the 1H NMR spectrum (lower part) is also presented. The spatial proximity of NH with N=CH (marked with a red arrow in Figure 2) or with CH2 (red arrow in Figure 3) proves the (E) or (Z) configuration of the N=C

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• of compounds 6a (red) and 8a (blue). Ugi–azide reaction for the synthesis of 1,5-DS-T-containing heterocycles. Proposed Ugi–azide-initiated synthesis of polyheterocyclic scaffolds 7 and 8. 4-CR vs stepwise Ugi–azide reactions for the synthesis of 7a. Synthesis of benzodiazepines 7a–k. Reaction

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• inverted hopping points can be found in high-density regions, plotted in red within their respective clusters across all molecules. The observed geometric differences and distinct clustering patterns suggest the existence of two separate S₁ → S₀ crossing channels. To test this hypothesis and investigate

• isosurface is 0.001. Absorption spectra and geometric overlays corresponding to Wigner-sampled geometries of 1 (a), 3 (b), and 5 (c) with XMS-CASPT2(8,9)/ANO-S-VDZP. Minimum energy path using XMS-CASPT2(8,9)/ANO-S-VDZP for 1 (a), 3 (b), and 5 (c). The dots on the graphs correspond to the S0 (black), S1 (red

• ), S2 (blue), and S3 (green) states. Relevant structures (S0 and S1 minima and endpoints of the MEP calculation) are shown below the plots. The C–N and N=N bond lengths are in angstroms on the structures shown. S1 energy is shown on the plot with a red star. (a) The bond lengths we calculated are

Measuring the stereogenic remoteness in non-central chirality: a stereocontrol connectivity index for asymmetric reactions

• Ivan Keng Wee On,
• Yu Kun Choo,
• Sambhav Baid and
• Ye Zhu

Beilstein J. Org. Chem. 2025, 21, 1995–2006, doi:10.3762/bjoc.21.155

• products are highlighted in grey color. The shortest connecting bonds between them are colored red. Accordingly, the asymmetric hydrogenation of 2-butanone is designated as [20] process because there are two connecting bonds between the stereogenic carbon and the stereochemical differentiation atoms, and

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

• or aziridine fragments. Dose–response curves for the cytotoxic effects of glycidyl esters of phosphorus acids 1–3 on human cell lines. (A) Human skin fibroblasts (HSF), (B) prostate cancer cells (PC-3), and (C) breast cancer cells (MCF7) were treated with diglycidyl methylphosphonate (1, red

• concentration of each compound. The dashed line marks the 50% viability threshold (IC50). Linear sweep voltammograms of 1 × 10−4 М HSA (black) and HSA mixed with each of the three alkylating agents; 1 (red), 2 (green), and 3 (blue). Conditions: supporting electrolyte: 0.1 M Et4NBF4, working electrode: glassy

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

• 1a (10 mM) in presence of 1 equiv of methanesulfonic acid (10 mM) recorded in a 0.325 M solution of Et4NBF4 in DMF (green line). Cyclic voltammetry of diimine 1a (10 mM) in presence of 2 equiv of methanesulfonic acid (20 mM) recorded in a 0.325 M solution of Et4NBF4 in DMF (dark-red line). Cyclic

• voltammetry of diimine 1a (10 mM) in presence of 3 equiv of methanesulfonic acid (30 mM) recorded in a 0.325 M solution of Et4NBF4 in DMF (light-red line). Glassy carbon as working, glassy carbon as counter, and Ag/AgCl as reference electrodes with 0.1 V/s as scan rate. Screening of the imino-pinacol reaction

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

• , 52.7, 39.4, 26.8; HRESIMS (m/z): [M + H]+ calcd for C18H21N2O6, 361.1400, found: 361.1404. Representative oxindole alkaloids. Orientation for the cycloaddition (left) and the crystal structure of the major stereoisomer 5a (right) with the anisotropic displacement parameters drawn at 50% (oxygen – red

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

• it is switched to one that absorbs at a higher wavelength (i.e., blue). The opposite phenomenon is called negative or inverse photochromism [3]. A shift towards higher energies is called hypsochromic or blue shift, while a shift towards lower energies is called bathochromic or red shift. When working

• conjugated with the chromophore structure, will influence its absorption spectrum and stability [4]. The solvent will also affect the properties, as it can stabilise or destabilise either the ground or the excited state, resulting in a red- or blue shift of the spectra. The thermal half-life (t1/2) measures

• wavelength (P-type) or through thermal back isomerisation (T-type). As a general rule, the absorption can be red-shifted by the choice of electron-donating rings (pyrrole, thiophene), while electron-withdrawing rings (pyridine, pyrimidine, pyrazole, imidazole, thiazole) give the opposite effect [12

Photocatalysis and photochemistry in organic synthesis

• Timothy Noël and
• Bartholomäus Pieber

Beilstein J. Org. Chem. 2025, 21, 1645–1647, doi:10.3762/bjoc.21.128

• Review article discussing photocatalysts capable of harnessing low-energy red light to trigger chemical reactions [19]. In addition to photoredox catalysis, several mechanistic platforms that leverage light – such as the use of electron donor–acceptor complexes [20], proton-coupled electron transfer [21

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• for the λem values of 18·Ba(ClO4)2. However, the situation was found to be different when the Δλem values were calculated. In this case, M06 (which even predicted a red shift) and PBE were the less accurate functionals, whereas M06-2X was the most precise functional, followed by wB97XD, the other

• perchlorate, as indicated in Figure 2 (X = O, Y, Z = Me). The possible coordination patterns are shown. NICS(iso) and NICSzz values at the molecular plane (z = 0) and 1 Å (z = 1) above this plane in a perpendicular direction. Points a–c correspond to the respective ring points, in light red. Perpendicular

Transition-state aromaticity and its relationship with reactivity in pericyclic reactions

• Israel Fernández

Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125

• between isoprene and methyl acrylate (black lines) and the analogous process catalyzed by AlCl3 (red lines) and projected onto the C···C bond-forming distance. (a) Evolution of the NICS(3, +1) values along a z-axis perpendicular to the molecular plane of the TS involved in the 1-butene and acetaldehyde

• acetaldehyde (black lines) and the analogous process catalyzed by AlCl3 (red lines) and projected onto the C···C bond-forming distance. AICD (a) and EDDB (b) plots for the transition state involved in the DGRT between ethene and ethane. Comparative activation strain analyses (a) and energy decomposition

• analysis (b) of the DGRT between ethane and formaldehyde (black lines) and the analogous process involving methanol (red lines) and projected onto the C···H bond-forming distance. AICD plots of the transition states associated with the Hopf cyclization reactions involving cis-hexa-1,3-diene-5-yne (a) and

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• photoluminescence (PL) spectra of (Sp)-6 and (Sp)-7 in diluted CHCl3 solutions (1.0 × 10−5 M) are depicted in Figure 1. The absorption bands are derived from the π–π* transitions of a phenylene–ethynylene conjugation system. The spectra of (Sp)-6 and (Sp)-7 are similar, and the absorption peak top of (Sp)-7 is red

• -shifted compared with that of (Sp)-6 because of the bent structure of the p-phenylene–ethynylene moieties in (Sp)-6 and extended π-conjugation of (Sp)-7. Such a red-shift of a UV–vis absorption spectrum has been observed in previously reported [2.2]paracyclophane-based cyclic oligomers [39]. CHCl3

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• local excited (LE) and charge-transfer (CT) states can be experimentally observed as dual fluorescence: a structured, higher-energy emission from the LE state and a broad, red-shifted emission from the CT state [8][9]. Classical systems such as 4-(N,N-dimethylamino)benzonitrile (DMABN) and pyrene-o

• : a structured band in the 450–500 nm region associated with the LE state of the Pe moiety, and a broad, red-shifted band in the 550–750 nm region attributed to the CT emission (Figure 3b). The CT emission showed strong solvent dependence, i.e., shifting to longer wavelengths and decreasing in