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

• -formylpiperidine and aminophenol (2a-o-hydrol) (see Figure 1a). To better understand the influence of the reaction conditions on product distribution, we plotted conversion versus selectivity in Figure 1b. Crudes were analysed by 1H NMR spectroscopy, as shown in Figure S1 (Supporting Information File 1), to

• piperidine. Reaction conditions: benzoxazole (0.1 mmol), piperidine (0.15 mmol), copper catalyst, solvent (1.0 mL). Conversion was measured by NMR spectroscopy (see Figure S1 in Supporting Information File 1 for an example). Reaction rate comparison between conventional (oil bath) and MW heating. Reaction

• conditions: benzoxazole (0.1 mol), piperidine (0.15 mmol), copper catalyst 20 mol %, solvent (1.0 mL). Conversion was measured by 1H NMR spectroscopy. TGA profiles of SIPERNAT silica and Si-MonoAm and Si-DiAm. Hot filtration test for the Si-MonoAm-Cu(I)-catalysed C2-amination of benzoxazole with piperidine

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

• byproduct and exhibited similar polarity as compound 5. The obtained compounds 3, 4, and 5 were identified using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) (see Supporting Information File 1) as well as single crystal X-ray diffraction analysis (vide infra). Furthermore, the

• internally functionalized DBC derivatives [22]. The dihedral angle between the mean planes of the two terminal benzene units is 83°, which is comparable to those of other derivatives. Next, products 3 and 5 were analyzed by variable temperature (VT) 1H NMR spectroscopy. The 1H NMR spectrum of bis-olefin 5 in

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

• OH functionality in compound 2 gives possibility to influence the tautomerism in this compound dynamically by protonation/deprotonation. The tautomeric and switching properties of compounds 1 and 2 have been revealed by using quantum-chemical calculations, UV–vis and NMR spectroscopy and UV

Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles

• Vladimir G. Ilkin,
• Pavel S. Silaichev,
• Valeriy O. Filimonov,
• Tetyana V. Beryozkina,
• Margarita D. Likhacheva,
• Pavel A. Slepukhin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104

• larger or even commercial scale. The structures of compounds 3 were confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry. The 1H NMR spectra are characterized by signals from protons of the aromatic rings in the range of 8.08–7.32 ppm, singlets for the proton at the C-3 position

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

• and LC–MS analyses (Figures S3–14), Marfey experiment (Figure S15) and the bioassay screen result (Figure S16). Acknowledgements We thank Russell Gray of the Marine Biodiscovery Centre, Aberdeen for assisting in NMR spectroscopy. Additionally, we are grateful to Blessing Akinboyo and Dr. Soji Fakoya

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

• optical absorption. The UV–vis absorption spectra, fluorescence properties and 1H NMR spectroscopy, indicate that 150 and 151 can be protonated to form the corresponding tropylium cation and consecutive dication under acidic conditions, with reversible protonation−deprotonation capabilities. Additionally

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

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

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

• 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

• distribution of 98% Z by UV–vis and 96% Z by 1H NMR. EWGs, such as NAc-PAP-CF3, on the other hand, showed a lower PSD for the Z isomer of 83% by both UV–vis and 1H NMR spectroscopy. For NMe- and NAc-PAPs, we observed increased Z content to almost quantitative photoisomerization after 365 nm illumination for

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

• -disubstituted pyrrolidine-2,3-diones were successfully synthesized via reversible transimination reaction. The structure of all compounds was evaluated using nuclear magnetic resonance (NMR) spectroscopy and, especially, with the molecular structure of compound 5a further confirmed through single-crystal X-ray

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

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• thermodynamically stable EE isomer was followed over time starting from the PSS@365 nm. The kinetic traces of the relaxation process were recorded by 1H NMR spectroscopy at 37 °C (Supporting Information File 1, Figure S2) and the population of the EE, ZE, EZ, and ZZ isomers were plotted against time. Using a

• glycocluster 1 [24] and the homobivalent azobenzene glycocluster 6αMan3αMan 2 and the glycoazobenzene-functionalized individual antennas 6αMan 3, 6βGlc 4, and 3αMan 5. The PSS was reached after irradiation with light of the denoted wavelength for 5 min and determined by NMR spectroscopy. Rate constants (k

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

• according to the results of 1H NMR dilution experiments. The molecular recognition behavior of the hosts C1 and M1 toward a panel of seven ammonium ions was explored by 1H NMR spectroscopy and isothermal titration calorimetry (ITC). We find that C1 generally binds slightly more tightly than M1 toward a

• ). Qualitative study of C1·guest recognition properties by 1H NMR spectroscopy Next, we decided to perform a qualitative investigation of the host–guest properties of C1 by 1H NMR spectroscopy. Figure 3 shows the chemical structures of a panel of guests that were studied and the complexation-induced changes in

• -association in phosphate-buffered saline (PBS) which might impinge on guest binding and complicate the determination of C1·guest binding constants. For this purpose, we performed dilution experiments monitored by 1H NMR spectroscopy. We prepared a series of NMR samples of C1 in D2O (from 4 mM to 125 μM) and

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• Scheme 1 and Scheme 2. The newly synthesized compounds were characterized by NMR spectroscopy as well as elemental analysis or high-resolution mass spectrometry. The experimental details and compound data are provided in Supporting Information File 1. Aldehyde 4, in which one of the formyl groups in

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

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

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

• , 13C NMR spectroscopy and high-resolution MS. 1H NMR spectra of obtained products contain characteristic signals of the protons of the methyl group in the region δ 1.72–2.16 ppm and proton of pyranone fragment in the region δ 5.98–6.62 ppm. Besides that, the key structures of synthesized products were

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

• for the construction of contiguous tetrasubstituted carbon centers via the Mannich reaction and this work. Plausible reaction mechanism. Catalyst screening for the asymmetric Mannich reaction. All yields were determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as an internal standard. N

• -Protecting group optimization for the asymmetric Mannich reaction. All yields were determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as an internal standard. aReaction conducted for 24 h. Catalyst screening using 7b as a substrate. All yields were determined by 1H NMR spectroscopy using 1,3,5

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

• photochemical reaction. Its structure was elucidated by NMR spectroscopy and single crystal X-ray diffractometry. The latter revealed no π–π interaction between neighboring ANTH cores. A combination of high photoluminescence quantum yield (PLQY) of 0.85 for 9,10-ANTH(BnF)2, its significantly improved

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

• of (R)-2-methyloxirane ((R)-2) with allylmagnesium bromide (3) catalyzed by CuI produced a mixture of (R)-hex-5-en-2-ol ((R)-4) and (S)-2-methylpent-4-en-1-ol ((S)-4’) (ratio 8:1, determined by 1H NMR spectroscopy) [25][26]. The primary alcohol (S)-4’ could be easily removed by a selective TEMPO

• the aggregation pheromone (4R,8S)-1, (4S,8R)-1, and (4S,8S)-1 were prepared through Li2CuCl4-catalyzed coupling and oxidation with RuCl3/NaIO4 from chiral building blocks (R)-10, (S)-10, (R)-11 and (S)-11, which were characterized by NMR spectroscopy and HRMS. Conclusion In summary, we have achieved a

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• agent 2.2 in a sub-stoichiometric fashion (20 mol %). However, even upon prolonged exposure, the yield of 2.3 did not exceed 20% (by 1H NMR spectroscopy). To achieve turnover, the photoreacted solid was subjected to a second grinding and exposed again to UV irradiation for an additional 16 h, which

• resulted in 40% yield. Alternating grinding and irradiation, the authors managed to obtain quantitative conversion of 2.1 to 2.3. Overall, in this work, mechanochemistry worked akin to agitation provided by stirring or heating in solution. In fact, 1H NMR spectroscopy, XRD and DFT analyses showed that

• when a 1:1 mixture of p-di[2-(4-pyridyl)ethenyl]benzene (5.1) and 4-benzylresorcinol (5.2) was ground with a mortar and pestle (1 h) and then irradiated with a low-pressure Hg lamp (60 h), [2.2]paracyclophane (5.3) was formed in poor yield (35% by 1H NMR spectroscopy). Dry vortex grinding did not

Electrochemical synthesis of cyclic biaryl λ³-bromanes from 2,2’-dibromobiphenyls

• Andrejs Savkins and
• Igors Sokolovs

Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32

• improving the substrate scope and understanding the reaction mechanism are in progress in our laboratory. Synthesis of cyclic diarylbromonium compounds. Substrate scope. Reactions were performed on a 0.15 mmol scale. Yields were determined by 1H NMR spectroscopy of the reaction mixture using 1,2,3,4

New tandem Ugi/intramolecular Diels–Alder reaction based on vinylfuran and 1,3-butadienylfuran derivatives

• Yuriy I. Horak,
• Roman Z. Lytvyn,
• Andrii R. Vakhula,
• Yuriy V. Homza,
• Nazariy T. Pokhodylo and
• Mykola D. Obushak

Beilstein J. Org. Chem. 2025, 21, 444–450, doi:10.3762/bjoc.21.31

• products were identified via NMR as 4,4a,5,6,7,7a-hexahydro-3aH-furo[2,3-f]isoindoles. The structures of compounds 5 were confirmed by NMR spectroscopy data (for details and discussion see Supporting Information File 1). The NMR data for the obtained furoindole skeleton signals and spin-coupling constants

• these compounds were confirmed by NMR spectroscopy (see Supporting Information File 1). Conclusion In summary, we showed the practical usage of 3-(furan-2-yl)acrylaldehyde in the four-component Ugi reaction with the prospect of further intramolecular [4 + 2] cycloaddition of the Ugi reaction product. We

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• investigated the role of the C-2 protecting group in Schmidt’s trichloroacetimidate glycosylation with donor 60 which showed excellent yield along with the formation of the 1,2-trans glycoside only. They proposed the mechanism with the help of NMR spectroscopy and the studies revealed that the N

• species was confirmed by low temperature NMR spectroscopy. Similarly, Ito et al. also introduced the concept of using 2-O-(o-tosylamido)benzyl (TAB)-modified donor 103 for the stereocontrolled synthesis of both 1,2-cis and 1,2-trans glycosides under modified reaction conditions [154][155]. They

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

• -ray diffraction analysis. Using two-dimensional correlation NMR spectroscopy methods, it was shown that the nature of the solvent significantly affects the equilibrium of the tautomeric forms of the 1,3-tropolones. The obtained compounds represent molecular switches of optical and fluorescent

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• and 13C NMR spectroscopy. All compounds were tested against five human microbial strains including three different strains of Staphylococcus aureus (ATCC 25923, ATCC BAA-41, and ATCC BAA-44), Escherichia coli (ATCC 8739), and Candida albicans (ATCC 90027) to evaluate their antibiotic potential. The

Synthesis of new condensed naphthoquinone, pyran and pyrimidine furancarboxylates

• Kirill A. Gomonov,
• Vasilii V. Pelipko,
• Igor A. Litvinov,
• Ilya A. Pilipenko,
• Anna M. Stepanova,
• Nikolai A. Lapatin,
• Ruslan I. Baichurin and
• Sergei V. Makarenko

Beilstein J. Org. Chem. 2025, 21, 340–347, doi:10.3762/bjoc.21.24

• -dihydronaphtho[1,2-b]furan-3-carboxylate 4a,b with a total yield of up to 73% (ratio 3a/4a = 2:1; 3b/4b = 2:1, according to 1H NMR spectroscopy) (Scheme 4). Using preparative chromatography, the mixture was separated into individual substances. In turn, alkyl 7,7-dimethyl-4,9-dioxo-6,7,8,9-tetrahydro-4H-furo[3,2