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

• available drugs [1]. These structures exhibit unique properties that influence pharmacokinetic and pharmacodynamic parameters, including lipophilicity, polarity, hydrogen-bonding capacity, and toxicological profiles [2][3][4]. Among them, five-membered multi-heterocyclic (FMMH) rings are privileged

• 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

• solvents (MeOH, H2O) whereas lower values were recorded for chlorinated solvents (CH2Cl2, CHCl3). This trend matches with the Lippert–Mataga plots generated for these compounds to verify the relationship between the large values of Stokes shifts and the Reichardt polarity parameters. The graphs shown in

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

• , demonstrating unequivocal structural identity with the natural isolates. Analytical HPLC confirmed the high purity (>95%) of all synthetic segetalins. However, experimental data for segetalin C revealed the existence of a multi-state conformational equilibrium in solution, which is dependent on solvent polarity

• –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

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

• simulations also suggest that the macrocycle of rotaxane 1-E tends to reside closer to the lipid–water interface, promoting more water accumulation than 1-Z, whose macrocycle positions deeper within the bilayer. This difference in localization likely arises from the substantial change in size and polarity of

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

• solvent polarity results in a decrease in rate constants. This phenomenon is attributed to the lower polarity of the transition state in comparison to that of the initial compounds [61]. Furthermore, these methods often require harsh reaction conditions, prolonged reaction times, and laborious

• space is shown in Figure 8a. The distribution of these selected solvents with other organic solvents in the 3D Hansen solubility space is determined by three Hansen solubility parameters (HSPs): dispersion (δD), polarity (δP), and hydrogen bonding (δH). As is well established, information about their

• potential hazard associated with their utilization as a solvent in the aforementioned reactions. For the solute component C,N-diphenylnitrone, the dispersion, polarity, and hydrogen bonding values for nitrone were determined as δD = 16.6, δP = 7.6 and δH = 8.7. Figure 8b clearly shows the position of the

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

• of the C–O bond “opens” the molecule, generating the corresponding merocyanine (Figure 2). The reverse photocyclization can occur upon exposure to visible light. Remarkably, the two isomers differ in their chemical and physical properties such as polarity, molecular volume, dipole moment

• photoisomerization to the merocyanine (open) form, FRET is activated – even when the macrocycle is relatively distant from the merocyanine – and becomes more pronounced as the donor approaches the acceptor. Moreover, this rotaxane exhibited tunable photoluminescence properties in response to solvent polarity, pH

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• polycyclic products in a highly diastereo- and enantioselective manner [45]. The polyene substrates were designed to facilitate a radical cyclization process, with alternating electron-poor and electron-rich olefins so as to enable polarity matching of the olefins and radical intermediates. With this design

• the type of radicals used can be overcome using photoredox catalysis. Synergistic photoredox and other forms of catalysis (using chiral Lewis acids, chiral Brønsted acids, H-bonding compounds, polarity reversal catalysts, etc.) expanded the scope of radical traps used and introduced alternate ways of

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• and co-workers achieved an innovative gold-catalyzed cascade cycloisomerization of 3-allyloxy-1,6-diynes to access cyclopropane- and cyclobutane-fused benzofurans/chromanols (Scheme 5) [12]. In this study, solvent polarity and trace water were identified as key parameters governing the reaction

• modulating reaction parameters – including solvent polarity, catalyst architecture, ligand electronic effects, and substrate strain effects – chemists can achieve unprecedented control over reaction pathways. This approach enables divergent access to complex molecular architectures from a unified substrate

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• was then treated with AcOH to afford the putative iminium cation to be chemoselectively reduced with NaBH3CN to ultimately reach the amine functionality. Through this protocol, the amine product was obtained, but it could not be isolated from silica gel for its high polarity. Thus, the extracted crude

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

• tautomerism is an intermolecular process that depends not only on the choice of aryl rings and substituents but also on concentration, solvent polarity, and the presence of proton sources [5][15]. In conclusion, the choice of aryl rings, substituents, and substitution position are all crucial to determine the

• soluble in water. For C- and S-diazocine, the absorption band separation of the two isomers is lower in polar solvents, resulting in worse PSS. In particular, for the S-diazocine it was found that the E-chair conformer was bathochromically shifted with increasing polarity of the solvent until completely

• side and electron-donating substituents on the other side giving the best performance (Figure 16, left). These peculiar compounds also showed increased stability and red-shift with increasing solvent polarity [87]. Oxidation of the sulphur atom to sulphoxide 69 introduces a sulphur-based stereocentre

Thermodynamics and polarity-driven properties of fluorinated cyclopropanes

• Matheus P. Freitas

Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137

• electrostatically complementary negative and positive faces. These interactions are mediated through electrostatic hydrogen bonds. This "Janus-like" polarity also facilitates interactions with ions, particularly sodium and chloride. These findings contribute valuable insights for the rational design of drugs and

• advanced materials, particularly those whose properties rely on the polarity and spatial arrangement of C–F bonds within a cyclopropane framework. Keywords: cyclopropane; fluorination; polarity; theoretical calculations; Introduction Cyclopropane, the smallest cycloalkane, has a rigid structure that

• polarity, with these effects varying based on the amount, position, and orientation of the fluorine substituents [7][8]. Mondal and colleagues have extensively reviewed additional properties of fluorinated cyclopropanes, including the conformational behavior of substituents attached to a fluorinated

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• of similar polarity (Scheme 10). Replacing the 2N-Troc protecting group with a 2N-Fmoc group in the imidate donor 121 led to formation of fully desymmetrized βGlcN(1↔1′)βGlcN disaccharide 122 with an improved isolated yield of 65% [95]. While the “armed” donors 79 and 121 were sufficiently reactive

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

• -carborane exhibit such behavior, where LE and CT states dynamically interconvert depending on solvent polarity and temperature [10][11][12]. When the interconversion is faster than radiative decay, the two states can reach thermodynamic equilibrium, and their relative populations are determined by the

• intensity as the solvent polarity increased, which are typical features of CT states (Figure S22 in Supporting Information File 1). The emission intensity of the CT band was almost comparable to that of the LE band of the Pe moiety in Pe–Ph–PTZ(TPA)2, whereas the emission intensity of the CT band is larger

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

• and solvent polarity, we demonstrate that the degree of protonation, and thus solution color, is highly temperature-dependent, changing from pale yellow to deep red as temperature decreases. We also present mechanistic insights and compare our experimental findings with computational results. Results

• strong acidity of MSA, moderate polarity of DCE, and the electron-donating substituents of 3, only 76 equivalents of acid (3.08 mM) is needed for nearly full protonation as indicated by the almost complete disappearance of the absorption peak at 360 nm. Similar data for compounds 1 and 2 in MSA/DCE

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

• as electron or hole-induced switching. Depending on the polarity of the bias, either an electron is injected (at positive sample bias) or a hole (at negative sample bias). This may be directly compared to the electron or hole-catalyzed isomerization of molecules in solution [40][41][42]. Generally

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• byproduct and exhibited similar polarity as compound 5. The obtained compounds 3, 4, and 5 were identified using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) (see Supporting Information File 1) as well as single crystal X-ray diffraction analysis (vide infra). Furthermore, the

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• displays red-shifted emission and prolonged fluorescence lifetimes as solvent polarity increases, indicating enhanced excited-state stabilization. Collectively, these studies offer valuable strategies for stabilizing long π-extended helicenes and finely tuning their chiroptical and emissive properties

• across the visible spectrum, with both emission intensity and chiroptical properties varying in response to solvent polarity. Concurrently, Würthner’s group developed two naphthalimide-annulated [n]helicenes, compounds 56a and 56b (n = 5, 6), via a concise two-step synthetic route that afforded excellent

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

• reasons are different. While in acetonitrile this is the effect of the increased polarity of the solvent, leading to stabilization of the more polar keto tautomers, in the non-polar chloroform it is caused by its proton-donative nature (formation of a stabilizing intermolecular hydrogen bonding with the C

• =O group of the keto tautomers [51][56]). The effects of acetone, methanol and DMSO, as seen, are based only on the increased (comparing to toluene) dielectric constant of the solvent, stabilizing in different extent the more polar KE and KK. The further increase of the polarity of the environment by

Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles

• Vladimir G. Ilkin,
• Pavel S. Silaichev,
• Valeriy O. Filimonov,
• Tetyana V. Beryozkina,
• Margarita D. Likhacheva,
• Pavel A. Slepukhin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104

• , the atom N(2) deviates from the RMS plane S(1)C(3)C(4)C(5) by 0.461 Å. The atom of the N(1) morpholine fragment has a planar configuration with significant asymmetry in the lengths of C–N bonds. Due to the electron-acceptor effects of substituents, the C(3)‒H bond exhibits significant polarity and is

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

• (Figure 2) [10][11][12]. As for the analogy to carbonyls, oxetanes display comparable polarity, spatial arrangement of the oxygen lone pairs and hydrogen-bond-accepting ability. In addition, they possess one major advantage and that is greater metabolic stability: while carbonyl groups are susceptible to

• methyls with an oxygen atom effectively eliminates its lipophilic character and reduces susceptibility to metabolic attack, while practically maintaining the molar volume. Because controlling polarity and metabolic stability is a major issue in medicinal chemistry, 3-substituted oxetanes have eventually

Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer

• Hao-Sen Wang,
• Lin Li,
• Xin Chen,
• Jian-Li Wu,
• Kai Sun,
• Xiao-Lan Chen,
• Ling-Bo Qu and
• Bing Yu

Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100

• positive and negative charges of two species can be stabilized by the electronic effects, these species are considered to be polarity matched during the HAT process. Conversely, when there is a polarity mismatch, the HAT process is likely to be impeded (Figure 2a). C–H bonds predominantly prefer to be

• nucleophilic, which smoothly facilitates the HAT process with amidyl radical. This effect is also called a polarity match [31][32][33][34][35][36][37][38][39]. 3) Considering the electronic effect, modifying the substituent of the N atom could tune the property of HAT capability (Figure 2b) [40][41][42][43

• structurally diversified target molecules 65–68 under optimized reaction conditions. In these cases, the high polarity of the radical intermediates of CF3CH2OH and 4-methylbenzonitrile, combined with the poor solubility of adamantane, may explain the possible reasons behind the reaction process [91]. Amidyl

Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers

• Kenichi Kato,
• Tatsuki Hiroi,
• Seina Okada,
• Shunsuke Ohtani and
• Tomoki Ogoshi

Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95

• chromatography on silica gel because of their low polarity and poor solubility in n-hexane. On the other hand, nitration of [3.3.3] gave solely the six-fold nitrated product due to low solubility of the starting material [46]. The current reaction is the first practical method for the selective

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

• investigations reported for the pure TTM and PTM systems. Also, the widespread assumption that the Q1 in triarylmethyl radicals is typically higher in energy than the D1 state, might not always hold true, as the polarity of the environment, for example solvents or matrices, might shift the respective energy

• -Mes1 has only a ϕ of 1% in toluene) and will not by itself induce a strong charge transfer as potent donors like Cz do. In DTM-Cz, the rotationally restricted Cz produces such a CT state even in its ground state, in solvents of high polarity [47]. However, upon excitation of TTM-Mes3 one of the mesityl

• Thiele radical, and TTH, and TFC are not as sterically congested as PTH. In TTH, the photoluminescence shifts with increasing solvent polarity while the ϕ increases from 69% in cyclohexane (λem = 691 nm) to 83% in chloroform (CHCl3) and 84% in toluene (λem = 716 nm) (see Figure 14a). This shift in the

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

• profound influence through multifaceted solute–solvent interactions [5]. Solvent polarity, hydrogen-bonding propensity, and dielectric characteristics collectively orchestrate stereodivergent pathways through dynamic coordination effects and differential stabilization of transition states. Notably, these

• the critical role of reaction medium polarity in modulating reactive intermediates, offering a strategic lever to toggle between C–H functionalization and reductive manifolds in photochemical transformations. In 2024, the Cheng group developed a palladium/chiral norbornene (NBE)-catalyzed cyclization

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• classical azobenzenes. Heterocyclic rings offer, for example, enhanced polarity, electron pairs for metal coordination [27], better water-solubility, and variable pKa [28][29]. Special attention has been given to 5-membered N-heterocyclic azobenzenes, which not only maintain the azobenzenes properties but

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

• criteria. In addition, the bioavailability radar (Figure 3) confirms that all compounds are predicted to exhibit favorable oral bioavailability, with two critical parameters, flexibility (FLEX) and polarity (POLAR) [27], aligning within the optimal range, as indicated by the pink area. Following the