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

• and tuning mix as internal standard or on a JEOL JMS-S3000 spectrometer for matrix-assisted desorption/ionization (MALDI) with trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) as a matrix. UV–vis absorption spectra were recorded on a JASCO V-730 spectrophotometer, and

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

• , along with decamer 3 (30%). High-resolution atmospheric-pressure-chemical-ionization time-of-flight mass-spectrometry (HR-APCI-TOF-MS) showed a molecular ion peak for 4 at m/z = 1479.4320 (calcd for C100H66N6S4, m/z = 1479.4305). The 1H NMR spectrum of 4 in acetone-d6 exhibited two NH signals at 9.07

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

• other transformations that can offer useful functionalities. These include ionization via protonation of one of the nitrogens forming the azo bond [12][13], azo–hydrazone tautomerization [14][15], and binding of analytes to side groups [16]. Such transformations depend on the azobenzene structure but

N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B

• Joy E. Rajakulendran,
• Emmanuel Tope Oluwabusola,
• Michela Cerone,
• Terry K. Smith,
• Olusoji O. Adebisi,
• Adefolalu Adedotun,
• Gagan Preet,
• Sylvia Soldatou,
• Hai Deng,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103

• the mass, m/z 236, [M + H]+ was generated from LC–MS data of the crude extract of the large-scale bacterial culture. The chromatogram clearly revealed an ionization with a corresponding m/z of 236.2102 in the mass spectrum, thereby confirming the presence of 4 in the crude extract. Compound 5 was

High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters

• Kelsey Plasse,
• Valerie Wright,
• Guoshu Xie,
• R. Bernadett Vlocskó,
• Alexander Lazarev and
• Béla Török

Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102

• , known entities and they were identified based on their high-resolution mass spectra. The mass spectrometric identification and purity determination of the products have been carried out by using an Agilent 7250 GC-QTOF mass spectrometer operated in electron impact ionization (EI, 70 eV) mode using a 30m

• the desired pressure and the pressure was maintained for the predetermined time. After removing the reaction tube, from the pressure chamber, the product was dissolved in ethyl acetate and the yield was determined by an Agilent 7250 GC-QTOF mass spectrometer operated in electron impact ionization (EI

• isolated by aqueous wash, neutralization with NaHCO3 and then extracted with ethyl acetate. The yield was determined by an Agilent 7250 GC-QTOF mass spectrometer operated in electron impact ionization (EI, 70 eV) mode using a 30m long DB-5 type column (J&W Scientific). General procedure for the catalyst

Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates

• Alexander S. Budnikov,
• Igor B. Krylov,
• Fedor K. Monin,
• Valentina M. Merkulova,
• Alexey I. Ilovaisky,
• Liu Yan,
• Bing Yu and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96

• ). Coupling constants are reported in Hertz (Hz). FTIR spectra were recorded on a Bruker Alpha instrument. High-resolution mass spectra (HRMS) were measured on a Bruker maXis instrument using electrospray ionization (ESI). The measurements were performed in a positive ion mode (interface capillary voltage

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

• and the ϕ (see Figure 8) [63]. In the meta-analysis the donor strength is approximated by the ionization energy (IE), which has been determined using DFT calculations. Plotting of the maximum emission wavelength and the ϕ versus the calculated IEs produces a systematic increase for λem and a bell

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

• necessary to elucidate the toxicological profiles of compounds 5c and 5e prior to consideration for drug development. Analysis of reactivity descriptors The primary reactivity descriptors, such as frontier molecular orbital energies (EHOMO and ELUMO), energy gap (ΔEL-H), ionization energy (IE), electron

• further purification. For column chromatography, 70–230 mesh silica 60 (E. M. Merck) was used as the stationary phase. Electrospray ionization–high-resolution mass spectra (ESI–HRMS) were acquired on a SCIEX X500 QTOF instrument in the positive ion mode. A Büchi melting point B-545 apparatus was used to

• optimized at the M062X/6-31+G(d) level of theory using Gaussian 16 software [48]. The reactivity, stability, and electronic properties of molecules determined by key parameters such as frontier molecular orbital energies (EHOMO and ELUMO), energy gap (ΔEL-H), ionization energy (IE), electron affinity (EA

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• observe two resonances for the C=O groups, three resonances for the aromatic C-atoms, two methyl resonances, three resonances for the bridging CH2 groups, and five of the six resonances for the sidearm (b and c) and equatorial glycoluril C-atoms. The negative-ion electrospray ionization mass spectrum

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• . The prepared samples were injected into the spray chamber using a syringe pump with flow rates of 10 to 40 μL/min. The desolvation gas was adjusted to 15 psi. Other parameters were optimized for maximal abundance of [M + H]+, [M + Na]+, or [M + K]+. High-resolution electron ionization mass spectra

Semisynthetic derivatives of massarilactone D with cytotoxic and nematicidal activities

• Rémy B. Teponno,
• Sara R. Noumeur and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 607–615, doi:10.3762/bjoc.21.48

• hertz (Hz). HPLC-DAD-MS analysis was performed using an amaZon speed ETD ion trap mass spectrometer (Bruker Daltonics) in positive and negative ionization modes. The mass spectrometer was coupled to a DIONEX UltiMate 3000 diode array detector [column 2.1 × 50 mm, 1.7 μm, C18 Acquity UPLC BEH (Waters

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• –240 mesh). Chiral HPLC analysis was performed using different chiral columns. IR spectra were recorded on an FTIR instrument. High-resolution mass spectra were performed by positive electrospray ionization using a quadrupole-time-of-flight detector (ESI+-Q-TOF) instrument. All compounds were purchased

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

• were obtained using a J-815 spectropolarimeter (JASCO Pfungstadt, Germany). The optical rotation, ECD, and UV–vis spectra of the newly described secondary metabolites were assessed in MeOH (Uvasol, Merck, Darmstadt, Germany). Analytical HPLC chromatograms and electrospray ionization mass spectra (ESIMS

• range from 190 to 600 nm. High-resolution electrospray ionization mass spectra (HRESIMS) were obtained using an Agilent 1200 Infinity Series HPLC-UV system (Agilent Technologies, Santa Clara, CA, USA) equipped with a C18 Acquity UPLC BEH analytical column (50 × 2.1 mm, 1.7 µm; Waters, Milford, MA, USA

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• supramolecular dimerization was triggered by observations in mass spectrometry experiments when exploring host–guest interactions. Positive-ion electrospray ionization mass spectrometry (ESI(+)MS) of a sample solution of cyclo[6]aramide H1 and a pyridinium derivative G1 in CHCl3/CH3CN (1:1, v/v) showed a

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• ). UPLC-MS analyses were performed on a Waters Acquity H-class UPLC with a Sample Manager FTN and a TUV dual wavelength detector coupled to a QDa single quadrupole analyzer using electrospray ionization (ESI). UPLC separation was achieved with a C18 reversed-phase column (Acquity UPLC BEH C18, 2.1 mm × 50

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• analyses were performed by using the ionization method ESI+ with a 6230 TOF LC/MS, Agilent Technologies. Unless otherwise noted, analytical grade solvents and commercially available reactants were used without further purification. Common reagents were purchased from commercial sources and were used

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• Agilent 5977A mass spectrometer. Agilent HP5-MS columns (Agilent Technologies, 30 m × 0.25 mm, 0.25 µm film thickness) were used as stationary phases, and helium was used as the carrier gas. EI-ionization was performed at 70 eV. The temperature program was as follows for both GC–MS and GC–IR: 50 °C (5 min

• distilled before use. All other chemicals were used without purification unless otherwise stated. Air- and H2O-sensitive reactions were performed under N2. ASAP-APCI-MS was performed on an Expression MS (Advion) mass spectrometer equipped with an APCI ionization source operated in positive mode. The

• , was inserted into the secretion sample and then directly into the ASAP ionization chamber. Scent glands Scent gland secretions of P. mangshanensis were collected from three adult males (1.3–1.7 m, X = 1.5 m) and three adult females (1.3–1.7 m, X = 1.5 m) living in the Bronx Zoo, New York, USA. All

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• solvent signals (DMSO-d6: 2.50 ppm (1H NMR) and 39.52 ppm (13C NMR)). High-resolution mass spectra (HRMS) were obtained on a Bruker micrOTOF II instrument using electrospray ionization (ESI). The melting points were determined on a Kofler hot stage apparatus. A magnetic stirrer IKA C-MAG HS 7 was used for

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• desorption ionization time-of-flight mass spectrometry (MALDI–TOF MS). The synthesized ion pairs showed similar electronic properties in solution state. In CH3CN, 2+-BF4− exhibited UV–vis absorptions at 273, 350, and 524 nm and fluorescence emission at 607 nm upon excitation at 524 nm. The absorption band at

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• proteome and enrichment-based methods. There are several chemical proteomics linkers reported that improve ionization of the probe–peptide conjugates or release a reporter ion during fragmentation or both (Figure 7). The reporter ion is important as it may serve two purposes. First, it facilitates the

• modified peptides can be used for side identification given the relatively high abundance and ionization efficiency due to remaining lysine. The use of the AzTB linker is practical for swift optimization of enrichment workflows, because after the probe–protein conjugates enrichment on the streptavidin

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

• Sabyasachi Chakraborty,
• Eduardo Mayo Yanes and
• Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

• distributions of five molecular properties: highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, HOMO–LUMO gap (Gap), adiabatic ionization potential (AIP), and adiabatic electron affinity (AEA). As shown in the violin plots in Figure 3B, for all properties, the

Divergent role of PIDA and PIFA in the AlX₃ (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

• Kevin A. Juárez-Ornelas,
• Manuel Solís-Hernández,
• Pedro Navarro-Santos,
• J. Oscar C. Jiménez-Halla and
• César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

• reference. At this stage, the PIDA–AlBr3 adduct undergoes ionization, giving rise to the corresponding ion pair I-1–Br (ΔG = −31.3 kcal/mol) in a highly exergonic and energetically favorable process. Next, an intramolecular SN2 reaction of the formed aluminum anion transfers a bromine atom to the

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• Thermo Fisher Scientific LTQ Orbitrap XL spectrometer with an Ion Max API source and analyses were made in the positive ionization mode if not otherwise stated. Infrared (IR) spectra were recorded on a Bruker Alpha II FTIR spectrometer with diamond ATR-module using the OPUS software package and are

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• diameter 0.8– 1.2 nm) were used. For centrifugal operation, Avanti J-E of Beckman Coulter and Hitachi Himac CS 150 GC II were used. Mass spectra were recorded on Bruker Autoflex III using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method with anthracene as the matrix for all

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• as the ionization product resulting from a consecutive two-photon absorption at the selected high laser intensity [69][70], yielding the corresponding long-lived radical cation with second-order decay that is typical for oxidized/reduced species, and a solvated electron as by-product. The latter is

• as the radical cation, Aza-H•+, which is in perfect agreement with our proposed photoinduced electron transfer step, while no triplet-excited Aza-H is observed (Figure 2A, blue spectrum). Since the direct ionization of Aza-H also contributes to this spectrum, we recorded a spectrum of only Aza-H in

• competes with ionization already during the laser pulse. Kinetic measurements of the radical cation species show multiexponential decay, probably due to recombination of the radical cation and radical anion (Figure 2A, inset). Despite the reported absorption maximum for 4CP•− at 398 nm [72], we were unable