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

• simple SiO2 column chromatography. In addition, they were purified using a recyclable high-performance liquid chromatography (HPLC) to remove unidentified impurities to obtain (Sp)-6 and (Sp)-7 in 16% and 3% isolated yields, respectively. The ultraviolet–visible (UV–vis) absorption spectra and normalized

• standard. Analytical thin-layer chromatography (TLC) was performed with silica gel 60 Merck F254 plates. Column chromatography was performed with silica gel 60N (spherical neutral). Recyclable preparative high-performance liquid chromatography (HPLC) was carried out on a Japan Analytical Industry Model

• LC918R (JAIGEL 1H and 2H gel-permeation columns) using CH2Cl2 as an eluent. Recyclable chiral chromatography (HPLC) was carried out on a YMC LC Forte/R (Chiralpak® IA column). High-resolution mass spectra (HRMS) was obtained on a Bruker Daltonics microTOF II spectrometer (APCI) by using sodium formate

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• liquid chromatography (RP-HPLC) using an acidic mobile phase [H2O (0.1% CF3CO2H)/MeCN 72:28]. As shown in Figure 4, the HPLC analysis of amidine 2 showed two peaks corresponding to the E and Z isomers which could be explained by the existence of E/Z isomers of amidine 2 trifluoroacetate salt. After

• separation of the two peaks, HPLC analysis of each separated component showed single peaks, suggesting that the E and Z isomers of amidine 2 trifluoroacetate salt could be separated by standard RP-HPLC. The configuration of the amidine moiety of each component was characterized by NOE experiments (for

• details, see Supporting Information File 1). The NMR and HPLC experiments clearly indicate that protonation of the amidine moiety increases the rotational barrier of the C–N bond, a result which is consistent with our DFT study. Since it was found that the E/Z isomers of amidine could be isolated as a TFA

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

• and rac-5 was conducted using high-performance liquid chromatography (HPLC) equipped with DAICEL CHIRALPAK IE as the chiral stationary phase (eluent: CH2Cl2/hexane 3:2 for 3 and 1:9 for 5). The absolute configurations of the enantiomers were determined by transformation of enantiomerically pure CBBC

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

• Fluorochem and used as received. The solvents used for the experimental synthesis (HPLC grade) were purchased from Sigma-Aldrich. All other materials were commercial products of analytical grade and used as supplied. Analytical TLC (thin-layer chromatography) was performed on Merck silica gel 60 F254

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

• purification by a reversed-phase high pressure liquid chromatography (HPLC) system which led to the isolation of four compounds, trivially named pseudomonins D–G (1–4) and three known compounds 5–7 (Figure 1). Compound 1 was isolated as a yellow oil. The molecular formula C11H13NO5 (Δ: −0.7 ppm, 6 degrees of

• by HPLC with a wavelength monitored at 340 nm of the derivatized amino acid residuals in the hydrolysate and threonine standards (see Supporting Information File 1, Figure S24). Compound 3 was isolated as a yellow oil. Its molecular formula of C11H11NO4 (Δ: −0.3 ppm, calcd. for C11H10NO4, 220.0615

• to an HPLC (Agilent 1290 Infinity equipped with a diode array detector) on a Phenomenex analytical C18 column (2.5 µm, 100 Å, 4.6 × 150 mm). Samples were eluted with a starting mobile phase of 5% acetonitrile (MeCN):95% H2O (0.1% formic acid), followed by a gradient of up to 100% MeCN for 15 min at a

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

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

• copolymers.a Supporting Information Supporting information includes general information, synthetic procedures and compound data, NMR and MS spectra, HPLC charts, and results of PXRD, DSC, TGA, gas adsorption, and theoretical calculations. Supporting Information File 2: Experimental. Acknowledgements The

Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• alcohols, 34 and ent-34, after recrystallization from hot hexane (100% ee by chiral phase HPLC, yield not reported). These alcohols were then treated with triphenylphosphine and iodine in the presence of imidazole to yield the iodides 35 and ent-35 (Scheme 2). The iodide intermediates were subsequently

• with vinyl acetate as the acylating agent, Amano lipase AK (AKL) was identified as the most effective biocatalyst for achieving selective acetylation, converting diol 28 to the monoacetate 37 in 91% yield with >99.4% de (by HPLC). The diacetate byproduct 39 was formed in a small amount (9%). A similar

• % yield over three steps. This compound was isolated in its pure form as a white solid after recrystallization from ethanol, confirmed by HPLC and NMR. In parallel, the primary alcohol group of ent-38 was protected as a TBDMS ether, and the acetate group was converted to a tosyl ester by hydrolyzing the

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• good yield with this straightforward methodology (and without the need for toluene reflux), and to determine the distribution of products obtained for this synthetic approach, by exhaustive analysis of reaction mixtures by HPLC, MS and NMR. Ultimately, 14 aminated derivatives of 5-chloro-3-(4

• -chlorophenyl)-[1,2,4]triazolo[4,3-a]pyrazine were synthesised, purified (≥95% purity, determined by 1H and 13C NMR and HPLC–MS analysis) and assayed for in vitro antimalarial activity. Results and Discussion Synthesis of aminated triazolopyrazine analogues The amination of 5-chloro-3-(4-chlorophenyl)-[1,2,4

• column chromatography (and additionally by HPLC for the toluene reaction), the reactions also gave comparable yields of compound 2 (70% for toluene/silica and 82% for only phenethylamine at room temperature). Only the tele-substituted product was observed in either reaction mixture, consistent with

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

• excesses were determined using chiral HPLC analysis using an Agilent 1260 LC instrument (Santa Clara, CA, USA) with Daicel Chiralcel AD-H column (Hyderabad, India) with a mixture of isopropyl alcohol and hexane as eluents. All liquid aldehydes were washed with saturated aqueous sodium bicarbonate solution

• afford the pure product 3. The enantiomeric excess was determined using chiral HPLC analysis with a mixture of iPrOH and hexane as eluent. Oxazolidine-containing bioactive compounds. Asymmetric catalytic synthetic methods of oxazolidine derivatives. Scope of aziridines and aldehydes. Proposed reaction

Pd-Catalyzed asymmetric allylic amination with isatin using a P,olefin-type chiral ligand with C–N bond axial chirality

• Natsume Akimoto,
• Kaho Takaya,
• Yoshio Kasashima,
• Kohei Watanabe,
• Yasushi Yoshida and
• Takashi Mino

Beilstein J. Org. Chem. 2025, 21, 1018–1023, doi:10.3762/bjoc.21.83

• reaction with nucleophilic lithium amide from n-propylamine, the reduction of phosphine oxide 9 by trichlorosilane/triethylamine, and the N-acylation of 10 with cinnamoyl chloride in three steps (Scheme 1). We also analyzed amide compound 7 by HPLC analysis using a chiral stationary phase column with a CD

• detector and found that the C(aryl)–N(amide) bond axial chirality exists in amide compound 7. We attempted the optical resolution of racemic compound (±)-7 and obtained (+)-7 and (−)-7 using a semi-preparative chiral HPLC on 50 milligram scales. We also investigated the racemization process associated with

• steps from phosphine oxide 8. Chiral HPLC analysis confirmed its axial chirality at the C(aryl)–N(amide) bond. The optical resolution of (±)-7 yielded (+)-7 and (−)-7. The racemization barrier of (−)-7 in n-dodecane was determined to be 25.0 kcal/mol at 25 °C, with a half-life of approximately 1.3 days

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

• mixture of right- and left-handed propellers can be resolved by chiral high pressure liquid chromatography (HPLC) into the P- and M-enantiomers, respectively [40][41]. However, due to the low racemization barrier of only about 22 kcal mol−1, the enantiomers racemize within minutes at room temperature. TTM

Data accessibility in the chemical sciences: an analysis of recent practice in organic chemistry journals

• Sally Bloodworth,
• Cerys Willoughby and
• Simon J. Coles

Beilstein J. Org. Chem. 2025, 21, 864–876, doi:10.3762/bjoc.21.70

• community risks becoming left behind without urgent cultural change. Journal data policies for the study timeframe, 01 February – 31 March 2023. ‘All data’ refers to: spectroscopic data (NMR, IR, UV–vis, Raman, circular dichroism and mass spectrometry), chromatography (GC, HPLC, SEC), physical data (m.p

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• containing potassium and magnesium ions at a physiological pH of 7.0 for 5 hours. Analysis of the reaction mixture by anion-exchange HPLC revealed that the bromopropyl handle (C3 homolog 8) gave the highest yield of covalently tethered HBC-RNA complex (50%). Significantly less RNA alkylation yield was

• RNA aptamer, using the same conditions as described above for the first series of RNA alkylation experiments (Figure 2). Analysis by HPLC revealed that the chloropropyl HBC derivative 12 was not reactive. Surprisingly, the iodopropyl HBC derivative 13 gave significantly lower yields than its bromo

• . HPLC traces were recorded with UV absorption by 260 nm. Structure-guided approach for engineering the (non-covalent) fluorescent light-up aptamer Pepper into its covalent counterpart [11]. a) Secondary structure of the Pepper aptamer [12]; b) chemical structure of the fluorophore HBC530 [7]; c) three

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

• )”, where A/B refers to the solvents used as mobile phase and a:b to their volume ratio. Analytical high-performance liquid chromatography (HPLC) was used to determine the purity of the obtained Fmoc-protected amino acids. The respective HPLC runs were carried out on a Primaide DAD system (VWR/Hitachi

• , Germany). The system works with a low-pressure gradient containing a HPLC pump (1110) with a 6-channel solvent degaser, an organizer, an autosampler (1210) with a 100 μL sample loop, a column oven (1310) and a diode array detector (1430). A Kinetex C18 (2) column (5 μm, 250 Å × 4.6 mm, Phenomenex

• ). After 2 h of stirring at 0 °C, H2O (30 mL) was added. After 1 h of stirring, the precipitated product was filtered, washed with H2O (15 mL), and dried in vacuo at 60 °C to give 6 (7.81 g, 9.39 mmol, 95%, 91% purity determined by analytical HPLC) as an orange solid. The crude was used without further

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

• each as white powder after HPLC purification of the mixture formed from reaction of massarilactone D with cinnamoyl chloride in triethylamine in the presence of catalytic amounts of 4-dimethylaminopyridine. The ESIMS of compound 3 exhibited the sodium adducts at m/z 507.20 [M + Na]+ and 991.39 [2M + Na

• Anton Paar MCP-150 Polarimeter with sodium D line at 589 nm and 100 mm path length. HRESIMS mass spectra were measured with a maXis ESI TOF mass spectrometer (Bruker Daltonics) [scan range m/z 100–2500, rate 2 Hz, capillary voltage 4500 V, dry temperature 200 °C], coupled to an Agilent 1200 series HPLC

• 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

Sequential two-step, one-pot microwave-assisted Urech synthesis of 5-monosubstituted hydantoins from L-amino acids in water

• Wei-Jin Chang,
• Sook Yee Liew,
• Thomas Kurz and
• Siow-Ping Tan

Beilstein J. Org. Chem. 2025, 21, 596–600, doi:10.3762/bjoc.21.46

• ,f) often precipitated out of the reaction mixture and were sufficiently pure (>95% by HPLC) after the simple washing steps, and the more polar hydantoin products could be extracted out of the reaction mixture with ethyl acetate and did not require further chromatographic purification. The “one-pot

Asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon centers by halogen-bonding catalysis with chiral halonium salt

• Yasushi Yoshida,
• Maho Aono,
• Takashi Mino and
• Masami Sakamoto

Beilstein J. Org. Chem. 2025, 21, 547–555, doi:10.3762/bjoc.21.43

• : Experimental procedures, characterization data, NMR spectra, and HPLC chromatograms. Funding This research was funded by an IAAR Research Support Program (Chiba Halogen Science: Halogen-Linkage of Molecular Functions); Chiba University Open Recruitment for International Exchange Program, Chiba University

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• a relatively fast and efficient conversion into the desired products. Further optimization of this promising photochemical method is currently under way in our laboratory. Isolation and characterization Pure samples of 9,10-ANTH(BnF)2 and 9-ANTH(BnF) were isolated by HPLC (Figure S3, Supporting

• photoirradiated 9,10-ANTH(BnF)2 solution contained only resonances for the starting material (20%) and for a single presumed photoproduct (80%) which retained the symmetry of 9,10-ANTH(BnF)2 (see Supporting Information File 1, Figures S7 and S9 (19F NMR)). An HPLC analysis of the photoirradiated ANTH solution

• revealed that at least three compounds were present, in accordance with an earlier report [32]. In the photoirradiated 9,10-ANTH(BnF)2 sample, the HPLC chromatogram shown in Figure S10 (Supporting Information File 1) showed 9,10-ANTH(BnF)2 (tR = 4.5 minutes) and a major product (tR = 6 minutes), in

Synthesis of the aggregation pheromone of Tribolium castaneum

• Biyu An,
• Xueyang Wang,
• Ao Jiao,
• Qinghua Bian and
• Jiangchun Zhong

Beilstein J. Org. Chem. 2025, 21, 510–514, doi:10.3762/bjoc.21.38

• , Mori and Phillips achieved the complete separation of the derivatives from the four stereoisomers by reversed-phase HPLC at −54 °C, and revealed that the natural pheromone consists of four stereoisomers of 4,8-dimethyldecanal (Figure 1) [16][17]. Previous syntheses mainly focused on chiral sources of

Synthesis of electrophile-tethered preQ₁ analogs for covalent attachment to preQ₁ RNA

• Laurin Flemmich and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 483–489, doi:10.3762/bjoc.21.35

• (16) see Supporting Information File 1. Syntheses of haloalkyl- and mesyloxyalkyl-modified preQ1 as and DPQ1 ligands. Supporting Information Supporting Information File 12: Experimental part, HPLC analysis of preQ1 and NMR spectra. Acknowledgements We thank Clemens Eichler (University of Innsbruck

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

• its enantioselectivity, aliquots of the reaction mixture were taken at defined time intervals and analyzed by HPLC using a chiral column after passing them through a short silica gel pad. Some interesting conclusions can be made from the data in Table 1. Firstly, the retro-Michael reaction occurs, to

• –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

• resolution of pure diastereomer anti-1. Supporting Information Supporting Information File 10: Characterization data, copies of spectra and HPLC chromatograms. Funding J.G.-P. thanks to the Universidad de Valladolid for a predoctoral fellowship. The Spanish MINECO (Project CTQ2014-59870 P) and the Junta de

Identification and removal of a cryptic impurity in pomalidomide-PEG based PROTAC

• Bingnan Wang,
• Yong Lu and
• Chuo Chen

Beilstein J. Org. Chem. 2025, 21, 407–411, doi:10.3762/bjoc.21.28

• impurity generated in this process. Nucleophilic acyl substitution competes with aromatic substitution to displace glutarimide and gives a byproduct that can co-elute with the desired product on HPLC throughout the remainder of the synthesis. Scavenging with taurine is a convenient way to minimize this

• iVeliparib-AP6. As a common practice for small-molecule library synthesis, the identity and the purity of the reaction products of this simple, 3-step process were analyzed by LC–MS. Whereas the HPLC traces of the reaction mixtures showed one major product peak, the final product carried a barely noticeable

• shoulder peak (Figure 2, marked with asterisk). A close examination of the UV profile indicated the presence of an impurity. Its removal requires repetitive prep-HPLC purifications that are inefficient and time-consuming. The isolated impurity lacks the characteristic fluorescent yellow color of

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

• acetone/MeOH (9:1, 7:3, 1:1, 0:1) along with one last fraction of MeOH 100% using 0.1% formic acid. Nine fractions of 1 L each were eluted that were collected and evaporated separately under reduced pressure to dryness. For fractions 3, 4, 6 and 8 were further purified using a PLC 2250 preparative HPLC

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• +) couple. Electrolyte solutions, at a concentration 0.1 M, were prepared from anhydrous, degassed HPLC grade CH2Cl2 and anhydrous Bu4NPF6. Voltammograms were recorded at a sweep rate of 100 mV s−1. Sample concentrations were ca. 1–2 mM. Electronic spectroscopy UV–vis–NIR spectroelectrochemical studies were