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

• stabilizing due to the presence of two anomeric-like interactions, nF → σ*CF [16]. According to a natural bond orbital (NBO) analysis, this electron delocalization accounts for a stabilization energy of 14.3 kcal mol−1 per interaction in compound 1.1. Similar stabilization values are observed in other

• electron delocalization effects. Among the difluorocyclopropanes, the stability order is 1.1 > 1.2-t. > 1.2-c., highlighting the destabilizing influence of 1,2-syn-diaxial repulsion in the 1.2-c. isomer. A similar interaction is observed in cis-1,3-difluorocyclobutane, where the diaxial conformer is

• 2.70 Å, this interaction is consistent with electrostatic hydrogen bonding. Consequently, similar to the behavior observed in the crystalline form of all-cis-1,2,3,4,5,6-hexafluorocyclohexane [10], 1.2.3-c.c. is expected to self-assemble in the condensed phase. Given the "Janus"-face-like structure of

Preparation of a furfural-derived enantioenriched vinyloxazoline building block and exploring its reactivity

• Madara Darzina,
• Anna Lielpetere and
• Aigars Jirgensons

Beilstein J. Org. Chem. 2025, 21, 1737–1741, doi:10.3762/bjoc.21.136

• attack to the double bond in intermediate A is kinetically preferred from the face forming the R-configured carbon of the C–N bond as a result of a minimized steric interaction of the oxygen in zwitterion with iPr substituent of oxazoline. Conclusion Unsaturated ester obtained by Torii-type ester

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• compound production, fundamentally involving the interaction between organic substrates and nitrating reagents. The intrinsic kinetics of nitration processes are governed by the synergistic interplay between the substrate’s molecular architecture and nitrating reagent reactivity. Distinct substrate

Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides

• Tsun-Yi Chiang,
• Mei-Huei Lin,
• Chun-Wei Chang,
• Jinq-Chyi Lee and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131

• modifications of bacterial polysaccharides, and the interaction of 4,6-O-pyruvylated pyranoses with lectins depends on the stereochemistry of the pyruvate ketal. Moreover, this chemical modification is crucial, as the distinct R or S diastereochemistry at the ketal center directly influences its biological

• , pyruvate ketals are attached to the O4 and O6 positions of galactose, incorporating a negatively charged carboxyl group. The diastereoselectivity and negative charge of pyruvate ketals have a key role in their biological interaction, such as influencing immunological specificity and patterns of

Influence of the cation in hypophosphite-mediated catalyst-free reductive amination

• Natalia Lebedeva,
• Fedor Kliuev,
• Olesya Zvereva,
• Klim Biriukov,
• Evgeniya Podyacheva,
• Maria Godovikova,
• Oleg I. Afanasyev and
• Denis Chusov

Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130

• has shown clear influence of the cation in the hypophosphite salt on the effectiveness of the reductive amination. The acidity of the reaction media was a key factor affecting the equilibrium in the interaction between carbonyl compounds and amines. Intermediately acidic media is the optimal for the

• media. Finally, the combination of H3PO2 and KH2PO2 1:1 with the ratio of H2PO2− to amine 1:2 is optimal balance between solubility of reductant, acidity of the medium and stability of the reducing system providing the highest efficiency of the interaction. Under optimized reaction conditions, the

• absence of an external hydrogen source. The alternative pathway to form a hemiaminal could not include the interaction of an acid with amine or aldehyde, nevertheless, the non-catalytic path had ΔEa = 32.1 kcal/mol (TS2→3'') which meant that hemiaminal definitely emerged faster via the amine protonation

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• condensation between 27 and the aldehyde afforded INT-A, which was activated by the CPA catalyst through hydrogen bonding interaction. The nucleophilic addition of isocyanide to Int-A produced INT-B bearing a stereogenic center. Subsequently, INT-B underwent intramolecular cyclization to generate axially

• explanations for such a diastereodivergence. Specifically, L9 functions as a monodentate ligand, and the stronger ligand–substrate hydrogen-bonding interaction and smaller distortion of the ligand resulted in endo-cycloadducts (L9-TS). In contrast, Trost ligand L10 serves as a bidentate ligand, and the smaller

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

• describe better the excitation process in the free state, whereas interaction of the sensor with Ba2+ requires the M06L functional. TDDFT analysis of the emission spectra shows larger errors, which have been corrected by means of a structural model. The bicolor behavior is rationalized based on the

• interactions. Finally, a spacer (denoted as X and Y in Figure 2) and a linker (denoted as Z) to anchor the sensor to a suitable surface via a covalent interaction are required. Ideally, different configurations and conformations of the fluorophore in the free and chelated states would result in a bicolor

• energies computed at 298.17 K. We also extended this study to the interaction between complexes 15a–d and benzene (14) and computed the corresponding complexation energies as In addition, Figure 4 includes the chief geometric parameters of the different complexes, as well as the corresponding free energy

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

• used in the synthesis of a good number of target molecules, including complex natural products [32][33][34][35]. Typically, the LA binds the dienophile through a donor–acceptor interaction (usually involving a carbonyl group) which results in a significant stabilization of the dienophile’s LUMO. As a

• reactivity [47][48] to quantitatively understand the origin of the acceleration in these pericyclic reactions. This model decomposes the electronic energy (ΔE) into two terms, namely the strain (ΔEstrain) that results from the distortion of the individual reactants and the interaction (ΔEint) between the

• TSs, it becomes clear that the lower barrier computed for the catalyzed cycloaddition is due to a lower strain (which derives from the higher asynchronicity of the process) and, mainly, to a much stronger interaction between the deformed reactants along the entire reaction coordinate. According to the

Chemical synthesis of glycan motifs from the antitumor agent PI-88 through an orthogonal one-pot glycosylation strategy

• Shaokang Yang,
• Xingchun Sun,
• Hanyingzi Fan and
• Guozhi Xiao

Beilstein J. Org. Chem. 2025, 21, 1587–1594, doi:10.3762/bjoc.21.122

• antitumor agent PI-88 (muparfostat), which retards tumor growth via inhibiting angiogenesis in two ways: 1) interaction with pro-angiogenic growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) and 2) by prevention of the release of angiogenic growth factors

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

• the degree of electronic interaction between the donor PTZ and acceptor Pe moieties, as indicated by the decreased overlap between HOMO and LUMO. UV–vis absorption spectra of the Pe–PTZ derivatives were recorded in benzene at room temperature (Figure 3a). All compounds exhibited characteristic

• than that of the LE band of the Pe moiety in other compounds. This suggests that the phenyl spacer effectively suppressed the CT interaction. It is noted that the substitution of the TPA group increases the relative amplitude of the CT emission band. On the other hand, it was found that the intensity

• dynamics of these molecules, transient absorption spectroscopy measurements spanning the femtosecond to microsecond timescales were conducted. When electron transfer occurs between the donor and acceptor, the spin–spin interaction becomes weaker, facilitating the formation of triplet excited states upon

Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer

• Yusuke Matsuo,
• Aoi Nakagawa,
• Shu Seki and
• Takayuki Tanaka

Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119

• two NH sites remained uncoordinated due to steric hindrance. Non-covalent interaction (NCI) plot analysis revealed distinct intramolecular π–π dispersion interactions between the two aza[5]helicene moieties (green surface in Figure 4b) [29][30][31]. Optical properties The electronic absorption and

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

• frontier molecular orbital (FMO) theory. Nitrile oxides are considered to be "type II" dipoles capable of reacting both through the interaction of HOMOdipole–LUMOdipolarophile and LUMOdipole–HOMOdipolarophile [35]. According to the results presented in [36], reactions with benzonitrile oxide can satisfy

• this case, the strong electron-withdrawing properties of the carboxyethyl group in CEFNO can significantly inhibit the reaction with 2f, lowering the energy of the HOMOdipole involved in the interaction. Instead, the reaction can proceed towards dipole dimerization [37], which is generally much easier

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

• adduct 10 was identified using GC–MS (Figure S1, Supporting Information File 1). When the reaction was performed under air-equilibrated conditions, the intended product 9a was obtained in a 31% yield, indicating that air influenced the interaction between the Ni-catalyst and the α,β-unsaturated carbonyl

• , pseudo-octahedral Ni(II) complex [44] involving the carbonyl groups of PS1 and 7a, which is further activated on aggregation of the pyridinium salt and the chromone aromatic ring through π−π stacking. Then, PC1 was submitted to Stern–Volmer quenching experiments. Whereas no interaction occurred between

• the excited form of PC1 and 3-bromochromone (7a), a direct interaction occurred between PC1* and morpholine (8a, Figure S3, Supporting Information File 1). Based on these results, the most plausible scenario might be that the reaction starts with the excitation of PC1 at 427 nm to generate the highly

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

• drastically reduced in MeCN (Figure S7 in Supporting Information File 1). This can be attributed to the less favorable protonation in MeCN as shown in Table 1. The interaction between compounds 1–3 and MSA was studied computationally by geometry-optimizing their ion pairs, denoted as 1H+MSA−, 2H+MSA−, and 3H

• −MSA), which acts as a single thermodynamic unit. However, interactions with solvent molecules, underrepresented in implicit solvation models, may weaken this interaction in practice [31][32]. Since a solvent’s dielectric constant increases when temperature decreases, the higher ∆H° values at lower

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

• voltage, which is ≈1.1 V. This suggests that while switching, the molecules may not be in their neutral state. Since the graphite–molecule interaction is weak and van der Waals-type, we use the gas-phase calculations and no major change in the electronic structure is expected for molecules upon adsorption

• charging, the potential energy landscape of isomerization changes, which supports the isomerization. As graphite–molecule interaction is weak and makes a capacitive interface between them, the molecules are likely stabilized in their ionic forms when a bias is applied at the tunneling junction. Charging of

Microwave-enhanced additive-free C–H amination of benzoxazoles catalysed by supported copper

• Andrei Paraschiv,
• Valentina Maruzzo,
• Filippo Pettazzi,
• Stefano Magliocco,
• Paolo Inaudi,
• Daria Brambilla,
• Gloria Berlier,
• Giancarlo Cravotto and
• Katia Martina

Beilstein J. Org. Chem. 2025, 21, 1462–1476, doi:10.3762/bjoc.21.108

• changes in the position and shape of the νNH2 and δNH2 bands are observed, which are an indirect indication of the interaction of the amino group with the metal (curve b) [51]. On the other hand, major changes are observed in the spectrum of 5 wt % Si –MonoAm-Cu(II) (curve d). These are particularly

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

• . It should be noted, however, that the relative stabilization of KE and KK depends, in addition, on the strength of the intramolecular hydrogen bonding. The interaction C=O···H–N is much stronger, which leads to better stabilization of KE. Some border cases of substitution in the phenyl ring of 1 are

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

• (89%). Interestingly, the fusion of two azulene units at peri-position induces the significant orbital interaction, resulting in a very narrow HOMO–LUMO gap in 172. Consequently, 172 exhibits NIR absorption properties (λmax = 1180 nm, tail to 1720 nm) and reversible redox behaviours (electrochemical

A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones

• Ashutosh Nath,
• John Mark Awad and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92

• the dienophile presents a negative charge (−0.280 to −0.325, 6a), (−0.280 to −0.327, 6h) and (−0.280 to −0.327, 6r), respectively. This structure induces electrostatic repulsion instead of the requisite attraction for a successful interaction between the electron-rich diene and the electron-deficient

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

• , thus confirming a strong interaction affinity lying within the 104 molar range. Gold extraction with β-CD and derivatives The possibility of using β-CD instead of α-CD in gold recovery and extraction is highly sought after by both researchers and industry because of the readiness of availability of β

• structures of the complexes of α-CD with KAuCN2 salts, with tubular representation for α-CD and space-filling for KAu(CN)2. The images at the center depict the interaction between one Au(CN)2− anion and one or two α-CD(s), according to the stoichiometry. The images at the sides depict the packing for the 1:1

Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

• Linqiang Wang and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

• of the catalyst for the next catalytic cycle. The electron-deficient aromatic aldehydes exhibit excellent stereoselectivity due to the π-stacking interaction between their aryl group and the electron-rich malonate group. Similar π-stacking interaction-controlled stereoselectivities were observed in

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

• yield. The reaction proceeds via a CeO2-coordinated carboxylate mode (Scheme 31A) [67]. In addition, the catalyst also offered high reusability for up to 4 runs thus further promoting the eco-friendliness. Carbonyl activation via Lewis acid–O=C interaction has also been achieved using other transition

• hand, carboxyl activation via Lewis acid–O=C interaction has also been developed. Ramachandran and Hamann (2021) directly prepared the amide 12 from cinnamic acid (7) catalyzed by BH3. The reaction proceeds via formation of the triacyloxyborane–amine complex intermediate 132 (Scheme 40A) [76]. The same

• vinylphenylboronic acid to synthesize the solid-supported phenylboronic acid catalyst (cat 1) which was used to convert cinnamic acid (7) to its corresponding amide 12 in moderate yield. The reaction involves dicarboxylate complex 135 formed through Lewis acid B–O=C interaction (Scheme 41A) [23]. The catalyst could

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

•  1 for CD-a-N-BB). Light-mediated reduction of triarylsulfonium salts. At this point, a Stern–Volmer analysis in the presence of tri-p-tolylsulfonium triflate (1b) as the model substrate was employed to quantify the quenching rate coefficient (Kq), in order to determine the interaction between the

• four different CDs from citric acid and from blackberries with triarylsulfonium salts. A diffusional rate value was found for all examined nanomaterials (Table 3), pointing to an efficient interaction between the photoexcited CDs and 1b. Cyclic voltammetry experiments have been carried out on both CDs

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

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• CT stabilization of the first excited state of the molecule [34]. This observation is further supported by the orthogonal D–A conformation calculated using DFT, which indicates a decoupled interaction between the HOMO and the LUMO (Figure 2). Moreover, compound 5e is the only member of the family in

• facilitated by reduced photocatalyst (PC) and the interaction of 15 with the radical cation of DIPEA. The best result, again, was attributed to molecule 5a with 60% isolated yield (Table 5, entry 1). In contrast, molecule 5b showed the worst performance with 41% NMR yield (Table 5, entry 2). For compounds 5c