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

• % 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

• undescribed amine analogues 2–15 were fully characterised following 1D/2D NMR, UV, and HRMS data analyses. X-ray crystallographic analysis of crystals obtained from the aminated products 2, 7, 10, and 15 are also reported here. The new library of amine-substituted triazolopyrazines was screened against the

• 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

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

• several methods, with 1H NMR titrations revealing a 1:1 stoichiometry in D2O (thus, 1:1 being preferential in solution). The binding constant (Ka) between Au(CN)2− and α-CD in D2O was determined to be 8.1 × 104 M. Titration calorimetry produced a binding constant value of 1.5 × 104 M for the 1:1 complex

A versatile route towards 6-arylpipecolic acids

• Erich Gebel,
• Cornelia Göcke,
• Carolin Gruner and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88

• aryl modifications in C6 position by utilising the chiral pool of a non-proteinogenic amino acid in combination with transition metal-catalysed cross-coupling reactions. Moreover, we present an in-depth NMR analysis of the key intermediate steps, which illustrates the conformational constraints in

• accordance with coupling constants and resulting dihedral angles. Keywords: conformational restraints; dihedral angle NMR; half-chair conformation; modified amino acids; pipecolic acid; stereoselective hydrogenation; Suzuki–Miyaura cross-coupling; Introduction Non-proteinogenic amino acids play an

• the Sonogashira–Hagihara cross-coupling products [35]. Furthermore, an in-depth NMR analysis was conducted on the resulting constraints leading to conformational structure predictions. ᴅ-2-Aminoadipic acid (1) [36], a side product formed in the pharmaceutical semisynthesis of 7-aminocephalosporanic

Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• investigate the association of HIMs with metal cations. NMR titration of HIM 1 with LiBArF20 led to distinct shifting of signals with the successive addition of salt. Figure 4 shows a titration of 1 with increasing equivalents of LiBArF20. The most dramatic changes included the aromatic proton multiplet at

• Information File 1, Figures S6 and S7). These results suggest that there are new associative processes occurring in the presence of both LiBArF20 and NaBArF24. The NMR spectral changes observed are mainly due to the binding of metals (lithium and sodium) to HIM 1. Additionally, some of these changes could be

• in this HIM system, the 1H NMR titration data was used to determine the association constants for metal coordination. Two stock solutions were prepared with one containing a concentration of 2.83 mM of the macrocycle (HIM) in a mixture of deuterated chloroform and acetone 1:2. The second stock

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

• (2R,5S)-2,5-diphenyl-3-tosyloxazolidine-4,4-dicarboxylate on the basis of comparison with reported NMR and specific rotation data [16]. The enantiomeric excess increased to 96% when the amounts of Sc(OTf)3 and L1 were increased to 10 mol %, but the yield remained moderate (38%) (Table 1, entry 5

• . Petroleum ether (PE, 60–90 °C fraction) and ethyl acetate (EA) were used as eluent. Reactions were monitored by thin-layer chromatography (TLC) on GF254 silica gel plates (0.2 mm) from Anhui Liangchen Silicon Material Co., Ltd. The plates were visualized by UV light. 1H NMR (400 MHz) and 13C NMR (101 MHz

• ) spectra were recorded on a Bruker 400 NMR spectrometer (Billerica, MA, USA), usually with TMS as an internal standard for 1H NMR and the centered peak of CDCl3 as an internal standard (77.16) for 13C NMR in CDCl3 solution. The chemical shifts (δ) were reported in parts per million (ppm) relative to

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

• (CO)12, to catalyze the alkyne hydrocarbonylation using CO and ZrF4 as the co-catalyst. The reaction afforded the corresponding amides 133, 277, and 278 in good yields via acyl carbonyl iron intermediate 280, which was observed by NMR (Scheme 69) [118]. By applying less toxic and safer CO2 instead of

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

• voltammetry of triarylsulfonium salts and NMR spectra. Funding Fondazione Cariplo (Photo and Mechano-Chemistry for the Upgrading of Agro- and Sea-food Waste to advanced polymers and nanocarbon materials, CUBWAM, project 2021–0751).

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

• allylic amination of acetate 12 with isatin (11a).a Supporting Information Data of thermal racemization of 7, DFT calculations for investigating racemization mechanism of 7, general methods and materials, experimental procedures and characterization data, 1H, 13C and 31P NMR spectra for 9 and 10, 1H, 13C

• and 31P NMR spectra and HPLC charts for (±)-7, (+)-7 and (–)-7, 1H and 13C NMR spectra and HPLC charts for (S)-13a–k (except (S)-13e) and (S)-16. Supporting Information File 18: Experimental section and compounds characterization. Funding This work was supported by a Grant-in-Aid for Scientific

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• position 4 of β-carboline by cross-coupling reactions. Thanks to its scalability, this novel approach ensures a broad accessibility to the target compound for potential pharmacological measurements. Using detailed NMR studies, the NMR signals have been assigned for both the base and its dihydrochloride

• brevicarine (2, isolated as its dihydrochloride salt). Based on the above results, Eschweiler–Clarke methylation of primary amine 25 was applied for the synthesis of N-methylbrevicarine (27) [39], a close structural analogue of alkaloid 2. The NMR data of our synthesized brevicarine (2) base and

• dihydrochloride salt are summarized in Table 1. Although a rudimentary 1H NMR spectrum of isolated brevicarine (2) base and some of the NMR signals were reported in 1969 [39], the signals were not fully assigned. However, the mentioned signals are identical to those of our synthetic product. All other

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• single regioisomer and diastereomer of B was formed (within the limits of 1H NMR detection), attesting to very selective reactivity. Here and in related projects, we found that many I(III) sources could generate a nitrenium ion, including iodosobenzene (PhIO) and iodomesitylene diacetate. However, unless

• synthesized in one pot with good yields and excellent diastereoselectivities (Table 4, entries 5 and 9). Surprisingly, carbamate substrates derived from di-substituted allylic alcohols (Figure 1) invariably failed to give the desired amino-sulfonoxylated products. With these substrates, 1H NMR analysis of the

• unpurified reaction residues showed a complex mixture of products. There were some signals suggestive of terminal alkenes, implying that olefin transposition was a competing pathway. With alkyne substrate 59, decomposition occurred, and the 1H NMR of the unpurified reaction mixture was illegible. With

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

• Supporting Information File 1, Table S3). As we expected, due to the blue-shifted absorption presented in molecules 4a and 6a, it was impossible to excite them under visible light (400 nm). Gratifyingly, PC 5a delivered product 8 with a promising 63% NMR yield. Next, we compare the photocatalytic behavior of

• compound 5a with the other family members utilizing the same dehalogenation manifold. Here, even slightly changes in the redox properties have an influence on the yield of the reaction. The D–A with the azepine analog (5b), gave the dehalogenated product 8 in 58% NMR yield (Table 2, entry 2). Quite

• previously reported by Zysman-Colman and co-workers [19]. Compound 5d showed the best performance with a 27% calculated NMR yield (20%, isolated yield) (Table 3, entry 3), while the azepine derivatives 5a and 5b led the transformation at 13 and 8%, respectively (Table 3, entries 1 and 2). However, these

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

• Zhiyang Zhang,
• Jialei Hu,
• Hanfeng Ding,
• Li Zhang and
• Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

• tricyclo[4.2.110,30.11,4]decane ring system. Additionally, krishnolides A and C contain 9–11 stereogenic centers and exhibit diverse oxidation patterns. Their relative and absolute configurations were determined through NMR, HRESIMS and ECD experiments, as well as single crystal X-ray diffraction analysis

• crystallographic data for this paper. These data can be obtained free of charge via the joint Cambridge Crystallographic Data Centre (CCDC) and Fachinformationszentrum Karlsruhe Access Structures service. Supporting Information File 8: Experimental procedures, NMR spectra and other characterization data for all

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• pyrazolo[1,5-a][1,4]diazepine core. aDetermined by 1H NMR spectroscopy analysis of crude reaction mixtures. bIsolated yield. Optimization reactions of the intramolecular post-Ugi heteroannulation.a Supporting Information Deposition Numbers 2410526 (for 16m) and 2441192 (for 17-cis) contain the

• characterization data and the copies of NMR spectra. Acknowledgements We gratefully acknowledge the National Natural Science Foundation of China (No. 21971174 and 21906114), Nazarbayev University Faculty-Development Competitive Research Grants Program (11022021FD2903), Nazarbayev University Collaborative Research

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

• afforded phenanthridinones. Intriguingly, switching to the electron-rich bidentate ligand bis(diphenylphosphino)methane (dppm) redirected the pathway to yield acridones. Time-dependent NMR studies revealed that the selectivity hinges on the aryne release kinetics from its precursor. Employing CsF

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• were synthesized via a one-pot strategy starting from macrocyclic precursors. Host–dicarboxylate binding was investigated using 1H NMR titrations, revealing that B4aH exhibits strong binding affinities toward a series of dicarboxylates, with association constants reaching up to 6896 M−1. The

• ultracycles in hand, we investigated the binding between the [2 + 2] ultracycle B4aH, which contains two electron-deficient cavities, and a series of dicarboxylate anions (C22−–C82− as tetrabutylammonium salts) by 1H NMR titration experiments (Figure 2). Taking C62− as an example, when it was added dropwise

• B4aH for C72− likely arise from cooperative noncovalent interactions and a size-matching effect. Conclusion In conclusion, we synthesized a series of hydroxy-substituted ultracycles of varying sizes on the lower-rim using a one-pot cyclization strategy. 1H NMR titration experiments indicate that the

Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes

• Patricia Gómez-Roibás,
• Andrea Chaves-Pouso and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71

• cases, with SIPr providing the best result (Table 1, entry 11). Under these optimized conditions, product 2 was isolated in 60% yield as a single diastereomer. The relative configuration of 2 was determined by two-dimensional NMR analysis (see Supporting Information File 1 for details). This

• )cyclopropanes by base-promoted intramolecular cyclization. Supporting Information Supporting Information File 2: Experimental procedures, characterization data and copies of NMR spectra. Funding Financial support from the AEI (PID2020-118237RB-I00), European Research Council (863914), Xunta de Galicia (ED431C

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

• NMR data by some journals supports author compliance. We find that, although authors meet mandated requirements, there is very limited compliance with data sharing policies that are only recommended by journals. Overall, there is little evidence to suggest that authors’ publishing practice meets FAIR

• identifiers for all reported compounds. Keywords: data availability; FAIR principles; journal guidelines; NMR data; organic chemistry; Introduction Fundamental to science is the ability of researchers to build upon the findings of others. Scientific data are no longer perceived as simply an output of

• ’ deposition in open repositories, and are these data accessible and curated? Is there evidence to suggest that authors apply FAIR data guidance? Does the existence of specific recommendations for FAIR data practice in publishing NMR data by some journals encourage compliance? Finally, we discuss what the

Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation

• Zhihua Liu,
• Ya-Zhi Chen,
• Ji Wang,
• Qingling Nie,
• Wei Zhao and
• Biao Wu

Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68

• by 1H NMR titrations in DMSO. The resulting complexes after solid–liquid extraction were also characterized by 1H NMR spectroscopy (Figure 3), showing consistent anion binding profiles. By comparing with free hexaurea receptor L, the chemical shifts of the urea units N–H in the obtained complexes are

• bonds. The average distance of N···O is measured at 2.85 ± 0.08 Å, which is comparable to those that are seen in the single crystal structure of Cs2SO4 (average distance is 2.9 ± 0.07 Å). Based on an NMR titration of hexaurea receptor L by adding CO32−, slow exchange of NMR signals is observed (Figure

• of Cs3PO4 over other cesium salts. The cooperative interactions between receptor-complexed caesium and anions were also supported by enhanced Cs+ binding affinity in the presence of anion-binding receptors. 1H NMR titrations were conducted by adding cesium (as tetraphenylborate salts) into the

Chitosan-supported CuI-catalyzed cascade reaction of 2-halobenzoic acids and amidines for the synthesis of quinazolinones

• Xuhong Zhao,
• Weishuang Li,
• Mengli Yang,
• Bojie Li,
• Yaoyao Zhang,
• Lizhen Huang and
• Lei Zhu

Beilstein J. Org. Chem. 2025, 21, 839–844, doi:10.3762/bjoc.21.67

• ). Optimization of reaction conditionsa. Supporting Information Supporting Information File 48: Full experimental details, characterization data and copies of NMR spectra of all products. Funding This work was financially supported by Project of Science and Technology Research of Hubei Provincial Department of

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

• straightforward development for specific applications. In this work, we synthesized novel N-acylpyrazole-based photoswitches and conducted a comparative study with 33 phenylazopyrazoles, comparing their photoswitching properties and the impact of electronic effects. Using UV–vis and NMR spectroscopy, we

• photostationary distribution (PSD) of the initial dark state could not be fully regenerated by photochemical means for all 33 PAPs (vide infra, ex-situ NMR measurements and thermal half-lifes). The recyclability of NH-PAPs was previously studied by Rustler et al. by altered irradiation with 365 and 420 or 455 nm

• the extent of photoisomerization, the isomer distributions of NAc-PAPs at the PSS365 and PSS445 were investigated using UV–vis and NMR spectroscopy. For the ex-situ 1H NMR irradiation experiments, we irradiated our samples in a cuvette until the PSS was reached and measured immediately afterwards the

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

• -pyrroline-2-ones 1a–e and 4-methoxybenzylamine (2) in absolute ethanol yielded 4-[1-(4-methoxybenzyl)amino]ethylidene-1,5-disubstituted pyrrolidine-2,3-diones 3a–e (Scheme 1) [19][20][21]. In addition to nuclear magnetic resonance spectroscopy (1D, 2D NMR), the structure of 3a has also been proven via

• ). Therefore, excess methylamine (40% in water, 47 equiv), served as both the solvent and nucleophilic reactant in the above reaction. In the 1H NMR spectrum of 3a, there are two doublets of doublets at 4.40 ppm and 4.49 ppm corresponding to two methylene protons (CH2) which are diastereotopic and therefore

• , show geminal coupling to each other [19]. However, in the 1H NMR spectrum of product 5a the above peaks were absent and the appearance of a new doublet at 2.76 ppm representing three protons from the methyl group (CH3) is observed. In addition, the 2D 1H–1H COSY NMR spectrum of 5a exhibited spin–spin

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• tools, UV–vis and NMR spectroscopy were utilized. We determined significant spectral features of the formed NBD species, including λmax and λonset values, all of which exhibit redshifts compared to their isocyclic counterparts. Additionally, the selected QC isomers were subjected to thermal and

• characterized using UV–vis and NMR spectroscopy, as well as high-resolution mass spectrometry. An overview of the synthetic and spectroscopic data for all derivatives is provided in Table 1, while the specific spectroscopic properties of the individual QC analogues can be found in Supporting Information File 1

• . Photoswitching The photoswitching of the NBDs to corresponding QCs was monitored by UV–vis and 1H NMR spectroscopy. With increasing electronegativity of the bridge-atom, a slight bathochromic shift in the absorption spectra of the parent NBD precursors O-NBD1 and N-NBD1 was found (Figure 2a and 2c). For the

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• the computational investigation, could not be isolated either – probably due to its high sensitivity to hydrolysis. However, a 2D 1H-15N NMR correlation spectrum showed no interactions of hydrogen nuclei in silicon-bound methyl groups and any of the nitrogens in the product. This led us to conclude

• that silicon is bound via the carbonyl oxygen in 12, as also shown by DFT computations. This is further corroborated by observation of a 13C NMR signal at 146 ppm for an sp2 carbon in the backbone of the product, which fits better for a C=N than a C=O bond. Recovery of the catalyst resting state 7 is

• , 13C, and 31P NMR as well as mass-spectrometric data of all synthesized compounds and selected crystal structures. Acknowledgements Portions of this work are included in the doctoral thesis of Christian Andreas Fischer, “Insights in Group 2 Metal Catalysis: New Ways and New Obstacles”, Friedrich

Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• Supporting Information Supporting Information File 30: Experimental procedures, characterization data for all new compounds, and NMR spectra of products. Funding We are grateful for the financial support from the China Postdoctoral Science Foundation (2021M692713) and the Natural Science Foundation of