Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• reaction of o-chloranil with benzoannelated derivatives of 2,3,3-trimethylindolenine, a comprehensive evaluation of the structure of the compounds obtained using quantum chemical methods, X-ray diffraction analysis, two-dimensional correlation NMR spectroscopy, as well as investigation of their ionochromic

• proton is shifted to a stronger field of 14.23 ppm and appears as a narrow singlet (Supporting Information File 2, Figure S17). Analysis of two-dimensional correlation spectra of heteronuclear NMR spectroscopy shows that compound 7a in DMSO-d6 solution exists in the (NH) tautomeric form. Thus, in the 1H

• spectrum of 7a, a correlation of the NH proton with the bridging carbon atoms C(3a'), C(9b'), and the quaternary carbon atom C(1') of the indolenine fragment is observed with δH 136.6 ppm, 134.0 ppm, and 53.6 ppm, respectively (Supporting Information File 2, Figure S20). The most important HMBC

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• fungus Beauveria bassiana [11]. Further confirmation of the depicted structure of 1 was obtained via its HMBC spectrum (Figure 2, Figure S8, Supporting Information File 1) that revealed key correlations from the two aromatic protons H-5'/H-9' to the C-3' and in turn a key correlation for H-3' to the

• one doublet methyl group at δH 0.94 (d, J = 6.6 Hz, H3-15) indicating its presence in the middle between both methyl groups. The latter together with a terminal triplet methyl group at δH 0.80 (t, J = 7.4 Hz, H3-14) further revealed key correlation to one tertiary and one secondary sp3 carbon atoms at

Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

• Misato Suganuma,
• Daichi Kitagawa,
• Shota Hamatani and
• Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

• prediction of thermal back reactivity. Moreover, we attempt to find the optimal functional for achieving a high correlation with experimental values by DFT calculation. Results and Discussion Photochromic properties in n-hexane Compounds N1–N3 were synthesized according to the procedures described in the

• of the aryl group on thermal reactivity, providing a foundation for future molecular modifications. Furthermore, DFT calculations identified M06 and MPW1PW91 as the most suitable functionals for accurately predicting the thermal back reactivity of aza-diarylethenes, achieving a high correlation with

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• , respectively) and chloroform (α = 0.20 and β = 0.10) [51], ΔδDMSO–CD3NO2 and ΔδDMSO–CDCl3 should follow a similar trend. Our 1H NMR experiments showed a strong linear correlation between ΔδDMSO–CD3NO2 and ΔδDMSO–CDCl3 for neutral HB donors (R2 = 0.985, Figure S15 in Supporting Information File 1), confirming

• percent populations of Me3PO and the corresponding HB donor conformer as two non-interacting molecules (see Supporting Information File 1 for details). We found a strong linear correlation between ΔGexp and ΔGcalc obtained at the PCM(MeCN)-M06-2X/6-31+G(d,p) level of theory (Figure 5 and Figure 6A). These

• values. The predicted Gibbs free energy of binding (ΔGcalc) was calculated at the PCM(MeCN)-M06-2X/6-31+G(d,p) level of theory. The counteranion for all cationic species is BF4−. A) Linear correlation between ΔGexp and ΔGcalc. ΔGexp and ΔGcalc values are shown in Figure 5. B) Linear correlation between

Hot shape transformation: the role of PSar dehydration in stomatocyte morphogenesis

• Remi Peters,
• Levy A. Charleston,
• Karinan van Eck,
• Teun van Berlo and
• Daniela A. Wilson

Beilstein J. Org. Chem. 2025, 21, 47–54, doi:10.3762/bjoc.21.5

• shape transformation experiments are indicative of a clear correlation between the dehydration of the membrane and its susceptibility to change shape through osmotic shock (Figure 3). Besides this, one final evidence for dehydration of the PSar corona was provided by NMR in Supporting Information File 1

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• -angle region, assigned respectively to as hch, for the disordered chains, and hπ, for the long-range core–core stacking resulting from strong polar–π interactions. The correlation length of the stacking was calculated by the Debye–Scherrer formula, which correspond to ca. 15–25 stacked molecules (Table

Ceratinadin G, a new psammaplysin derivative possessing a cyano group from a sponge of the genus Pseudoceratina

• Shin-ichiro Kurimoto,
• Kouta Inoue,
• Taito Ohno and
• Takaaki Kubota

Beilstein J. Org. Chem. 2024, 20, 3215–3220, doi:10.3762/bjoc.20.267

• 2.43) and methylene carbon C-22 (δC 46.3), and between H2-22 (δH 3.73) and N-methylene carbon C-20 (δC 58.7), indicated that C-22 was connected to 20-N. Additionally, an HMBC correlation was observed between H2-22 and the non-hydrogen-bearing carbon C-23. Considering the chemical shift of C-23 (δC

• ]. Despite the absence of an HMBC correlation directly indicating a connection between C-8 and C-9, the HMBC correlation between the N-methylene protons H2-10 (δH 3.66) and the carbonyl carbon C-9 (δC 161.5), along with the molecular formula of compound 1 by process of elimination, suggested that C-8 and 9-N

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• 3.33, 1.91, 2.21), and a three-bond HMBC correlation from δH 3.33, and a two-bond correlation from δH 2.20 to the carbonyl resonating at δC 173.9 [15]. The observation of a 3JCH correlation from δH 3.20 to the nitrogen-bearing carbon at δC 46.4 and to δC 173.9 supported the assignment of the

• confirmed by HMBC correlations (Figure 3). This fragment was connected to the previously assigned moiety through a HMBC correlation from δH 3.25 to the amide carbonyl (δC 164.9), thus enabling the full chemical structure of ianthelliformisamine G (7) to be assigned. Compounds 6 and 7 are both commercially

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• isomers, two due to the E and Z isomers of the imine group (–N=CH–) and two due to the syn/anti-conformers of the amide bond (–NH-CO–). Experimentally, the E isomer is often more stable and so, predominant. The strong correlation between the NH and CH of the imine observed in 2D 1H-1H NOE experiments for

• the two conformers of hydrazones 3e and 3f (see Supporting Information File 1) is in accordance with the E stereoisomers. Furthermore, another correlation is observed for one conformer involving the NH of the imine on one side and the α-proton and the CH2 of the Cbz of the phenylalanine on the other

• . This correlation is present for one conformer (anti) and not for the other (syn), and this observation is similar for hydrazones 3e and 3f (see Supporting Information File 1). Based on these experimental data we can hypothesize the geometry of the two conformers of hydrazones 3e and 3f is E,syn and E

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• due to the lack of suitable reference acids in the weakly acidic pKa region in acetonitrile only two reference acids were used. The results are presented in Table 2. We estimate the standard uncertainties of the assigned pKa values of BFC and FIC as 0.15 pKa units. pKa predictions using correlation

• analysis The pKa values of fluorene, indene, cyclopentadiene, 9-phenylfluorene, and diphenylmethane in acetonitrile were estimated by averaging the values obtained from their experimental pKa values in DMSO [5] and three correlation equations: equations 2.1 and 2.2 in Ref. [13] and correlation equation

• obtained from different equations is not good. Therefore, the standard uncertainties of these obtained pKa estimates are high: 2 pKa units for fluorene, indene and 9-phenylfluorene, 3 pKa units for cyclopentadiene (as this acid is very different from the acids used for developing the correlation equations

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• is no obvious correlation between the quantum yields of the photoreactions and substitution pattern of the norbornadiene in this series, except for a rough trend that naphthyl-linked derivatives, in particular the ones substituted in the 2-position, have lower quantum yields than the phenyl-linked

• ones. This lack of correlation may indicate that several different factors and processes contribute to different extent to the course of the photoreaction, for example, steric hindrance and resulting torsion angles between the arene unit and norbornadiene, deactivation of the excited state by

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• configuration of the double bond was confirmed using 1H,1H-NOESY spectroscopy. As shown in Figure 2, a correlation between protons of the allyl moiety and the aryl substituent evidenced their spatial proximity in molecule 1c. The absence of a correlation between allyl and vinyl protons additionally supported

4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions

• Maurice Médebielle,
• Peer Kirsch,
• Jérémy Merad,
• Carolina von Essen,
• Clemens Kühn and
• Andreas Ruhl

Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246

• enantiomers (R,R)-3/(S,S)-3, (R,R)-4/(S,S)-4 were obtained by slow evaporation from n-heptane solution and structures were determined by X-ray diffraction, which allowed the correlation of the chiroptical properties with the configuration (Figure 2 and Figure 3). The HTP of all enantiomers were measured with

Structure and thermal stability of phosphorus-iodonium ylids

• Andrew Greener,
• Stephen P. Argent,
• Coby J. Clarke and
• Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

• phosphoranyl(aryl)iodonium compounds 1f–i, no direct correlation between the substituents’ Hammett parameter σp and the decomposition onset temperature Tonset was observed (Supporting Information File 1, Figure S13). However, the DSC thermograms of iodonium ylids with electron-poor aryl substituents (1h,i

• -iodonium ylids at 10 °C min−1 in N2 (full dataset in Supporting Information File 1). (b) First derivatives of TGA thermograms normalised to the intensity of the first peak. (c) Correlation of Tonset with the dihedral angle φ (between the R–I–X bond and the plane of the arene substituent). (d–g) DSC

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• unambiguous assignment of the signals for the methine and methylene groups of compounds 4 and 5 was carried out based on the correlations found in the NOESY 1H,1H and HMBC 1H,13C spectra. As an example, the key correlation interactions for compounds 4d and 5d are depicted in Figure 3. Thus, in the NOESY

• C-3 of the imidazole core, would not be possible for the alternative imidazopyrimidine system. These results allowed us to reject the structure 11. The lack of correlation in the HMBC spectra between the protons of the amide fragment and the C-5 carbon atom, as well as the presence of cross-peaks of

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• recorded on Bruker AVANCE 300 III, 250II, or 500 spectrometers. The analysed chemical shifts δ are referenced to the residual solvent signals of the deuterated solvents CDCl3 (δ = 7.26 ppm/77.16 ppm). Multiplicities due to spin–spin correlation are reported as follows: s = singlet, d = doublet, dd = double

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• process. Considering a reaction with six stationary points (REACTANTS, E1, TS2, E2, TS3, and PRODUCTS), which can be catalysed by n potential catalysts, the program calculates the correlation between the energy span and all possible pairs of stationary points for the n catalysts. For instance, it

• utilised. The same variables (energy of pre-TS01 assembly and Min2) were considered, which yielded a correlation with a R2 value of 0.71. As depicted in Figure 7A, it is clear that the best family for this mechanism is family 2, followed by families 3 and 4. Family 1, similar to the previous group

• indicated. Coupling reaction between PO and CO2. Depending on the catalyst considered, the reaction follows mechanism 1, 2, or 3. VOLCANO plot group 1. The free energies of pre-TS01 assembly and Min2 are considered for the correlation. (A) On the left, the compounds of families 1, 3, 4, and 5 were used for

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• the supramolecular fibres, CSLM was used to identify the mode of molecular assembly of each component. By comparing the CSLM images arising from the different fluorescent probes, there was shown to be a weak correlation between the resulting images, indicating that the fibres self-sort and separately

• accessibility of such techniques can be limited [77]. It has been previously established that there is a direct correlation between the bulk properties of self-assembled materials and their nanostructures [79][80] and microstructures [81][82]. Recently, Adams et al. utilised SANS to quantify the fibrillar

• nanostructure [79]. To investigate the effect of the gelator concentration on the density of the hydrogel network, SANS was used to determine the correlation length (Figure 17). As the concentration of the gelator increased, a decrease in the correlation length was measured which evidences a decrease in the

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• concentrations. Determining the intrinsic reaction kinetics Given the strong correlation between the observed HNO3-based reaction rate constant and the H2SO4 mass fraction, intrinsic reaction constants independent of H2SO4 concentrations were determined to study the intrinsic kinetics of the reaction. Previous

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• ]. While the accuracy of the model is paramount, interpretability is also highly desirable. In this regard, MLR bears the advantage that it yields a directly interpretable function which can be used for mechanistic inference. However, it is important to note that the caveat of correlation and causality

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• -free extract as a reference. Correlation of fluorescence intensities and protein concentrations Plasmids for CFPS were expressed in E. coli BL21 (DE3) and purified as described by Rolf et al. [18]. The quantifications of purified proteins and set dilution series were performed with the Bradford assay

• . Fluorescence was measured with FLUOstar® Omega multi-mode microplate reader (BMG LABTECH, Ortenberg, Germany) under the same conditions as for the in vitro-produced proteins to determine the correlation between fluorescence intensity and protein concentration for each protein. Fractional yield The fractional

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• /chemoinformatics calculations were also performed to correlate the observed reactivity with the charges on the carbonyl group of 1,3-diketones. Unfortunately, no reliable correlation was found between the charges and the reactivity of the 1,3-diketones with the present set of heterocyclic substituents or with the

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• carbon (δC 70.1), and one of the methylene carbons (C13: δC 44.8). The formyl proton H7 showed HMBC correlations to the olefinic carbons C3, C4, and C5 and the olefinic methine proton H5 was correlated with C2, C3, C4, and C7. These correlation data allowed the assignment of a carbon sequence C2–C3–C4–C5

• and the attachment of the formyl group at C4. Furthermore, HMBC correlations from two methylene protons H28 to the olefinic carbons C2, C3, and C4 connected the chain part at C3. A 1H,15N-HMBC correlation was seen from H5 to a nitrogen at δN 161.4, which suggested the presence of a nitrogen atom

• adjacent to C5. A correlation to the acyl carbonyl carbon (C6) was not available at this stage. In order to obtain further information for connectivity, compound 1 was reacted with methyl iodide and K2CO3 to give a bismethylated derivative 1a. A methyl proton at δH 3.94 was of an N-methyl group (δC 38.5

2-Heteroarylethylamines in medicinal chemistry: a review of 2-phenethylamine satellite chemical space

• Carlos Nieto,
• Alejandro Manchado,
• Ángel García-González,
• David Díez and
• Narciso M. Garrido

Beilstein J. Org. Chem. 2024, 20, 1880–1893, doi:10.3762/bjoc.20.163

• α4β2 nicotinic cholinergic receptor ligands with nanomolar activities in rat brain homogenates (Scheme 2). The idea behind these AEP structures was to check activity correlation against a nicotine series. The comparison of Ki values of both series showed a moderate correlation, which opens the

• )-[3H]-baclofen displacement. QSAR studies have been developed in order to examine the pivotal role of the aromatic moiety of baclofen-like compounds [25]. In this sense, the QSAR equation revealed HOMO/LUMO orbital energies are critical for a high correlation with binding strength. An in vivo