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

• in the preparation (theoretical loading). This suggests that optimum catalyst distribution and activity is achieved with 5 wt % supported CuCl. The two catalysts were also characterised by FTIR and DR UV–vis spectroscopy, to obtain information about the grafted aminopropyl ligand and inserted copper

• 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

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

• absence of carbonyl groups in bis-olefin 5 has been corroborated by Fourier transform infrared (FTIR) spectroscopy (Figure S16 in Supporting Information File 1). Compound 4 could be generated through the reaction of compound 3 with phosphorus ylide. However, a reliable reaction mechanism remains unclear

• 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

• intramolecular hydrogen bonding, keep planarity. However, this situation means that changes in their molar fractions cannot be detected by use of UV–vis spectroscopy, i.e. the tautomerism could be considered only in the frame of change between E and (KE+KK). In the spectra, shown in Figure 2, two distinct

• and KK (both below 5%) could be observed in amounts around the detection limit of optical spectroscopy, which finally should not lead to substantial spectral changes comparing to toluene. The absorption spectra, shown in Figure S10 (Supporting Information File 1), suggest a different story. The

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

• , it was reported that PAH 126 exhibits anti-Kasha fluorescence [80] from the S3 state in the range of 410–470 nm upon excitation at 370 nm. This was well verified by femtosecond time-resolved absorption spectroscopy (fs-TAS), with corresponding high-energy excited state absorption bands observed at

• 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

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

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

• via hydrothermal treatments have an amorphous structure. The optical properties of the prepared CDs were thus investigated by UV–vis absorption spectroscopy. The obtained spectra (Figure 1) showed three main absorption bands located at 225–235 nm (assigned to, according to the literature, the π–π

Synthesis of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones by domino C–N coupling/hydroamination reactions

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

Beilstein J. Org. Chem. 2025, 21, 1010–1017, doi:10.3762/bjoc.21.82

• ]pyrimidine-2,4(3H)-diones 4 were investigated by steady-state absorption and photoluminescence spectroscopy (Figure 2, Table 2). The wavelength and intensity of absorption and emission depended on the substitution pattern. The methyl-substituted compound 4a showed one broad absorption band at ≈290 nm. A

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

• (because of spin selection rules forbidding the direct transition from the quartet to the doublet state). While for TTM and PTM substituted with weak donors such energetically low-lying quartet (Q1) states have been observed in TD-DFT calculations [20][62] and EPR spectroscopy [63], there are no such

• the non-radiative pathways, while the rates for emission remain almost unchanged between the donor-functionalized TBTM and TTM series [73]. This effect has also been investigated by excited state vibrational spectroscopy, where (among other compounds) TTM-TPA and TTM-3PCz have been investigated [74

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

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

• about many standard formats [73]. Open formats in NMR, mass spectrometry, UV–vis-, IR, and Raman spectroscopy have been recently reviewed [74]. Often a very simple first step is to export coordinate spectroscopic data to CSV, and there are numerous online tools for conversion of proprietary to open file

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

• absorption spectroscopy With a set of photoswitches at hand, we studied the obtained PAPs through UV–vis absorption spectroscopy. The photochemical properties are summarized in Table 1. All compounds show absorption maxima in the range of 324–368 nm in CH3CN, which corresponds to the strongly allowed π→π

• 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

• spectroscopy, the structure of 4-(1-methylamino)ethylidene-1,5-diphenylpyrrolidine-2,3-dione (5a) was also verified through single-crystal X-ray diffraction. Furthermore, the synthesized molecules were evaluated for compliance with established drug-likeness rules (Lipinski, Veber, Ghose, Egan, and Muegge), as

• -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

• -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

• published tailor-made fitting program [24], the rate constants k1–k4 were extracted from the kinetic traces and are summarized in Table 2. The thermal relaxation of the glycoazobenzene antennas 3, 4, and 5, on the other hand, was monitored by UV–vis spectroscopy at 37 °C and the rate constants k5, k6, and

• 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

• spectroscopy and quantitative investigation by isothermal titration calorimetry (ITC). Finally, we discuss the trends in binding affinity observed for C1·guest and M1·guest complexation. Design, synthesis and characterization of C1 In order to disentangle the effects of the ionic group (sulfonate versus

• ). 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

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

Total synthesis of (±)-simonsol C using dearomatization as key reaction under acidic conditions

• Xiao-Yang Bi,
• Xiao-Shuai Yang,
• Shan-Shan Chen,
• Jia-Jun Sui,
• Zhao-Nan Cai,
• Yong-Ming Chuan and
• Hong-Bo Qin

Beilstein J. Org. Chem. 2025, 21, 601–606, doi:10.3762/bjoc.21.47

• and C7 in simonsol C was confirmed by 1H-1H ROESY spectroscopy. Conclusion The total synthesis of (±)-simonsol C was accomplished using a dearomatization reaction under acidic conditions as key step to construct the aryl-containing quaternary center. The 6/5/6 benzofuran unit was formed through

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• for the formation of intermediates. Gao et al. studied the generation of metal acetylide A by IR spectroscopy [65]. When subsequent additions of 1 equiv FeCl3 were made in a solution of alkyne and TMG, the C–H stretch peak at 3277 cm−1 started to decrease as the temperature increased from 30 to 100 °C

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

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• binds free tryptophan selectively in aqueous media. Furthermore, it is capable of binding to tryptophan within model tripeptides. The naphthalene functionality in the glucose-derived receptor enables the study of guest binding using fluorescence spectroscopy. Keywords: amino acids; macrocyclic

• acids in H2O by 1 was investigated by ITC measurements and titration experiments monitored by fluorescence spectroscopy. The results are summarized in Table 1. Receptor 1 binds tryptophan with the highest affinity among the investigated amino acids (entry 1, Table 1). The Ka of the complex between 1 and

• peptides for binding we prepared the derivatives of peptides 2–4 bearing an acetyl-capped N-terminus (compounds 5–7). As a control we also studied tripeptide 8 containing exclusively alanine residues. The binding of tripeptides was again studied by ITC and fluorescence spectroscopy and the results are

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

• ANTH derivatives with fluorinated substituents (the highest is Φf = 0.97 for 9,10-ANTH(C8F17)2) [25]. Several comparative photostability studies for unsubstituted ANTH and ANTH derivatives using UV–vis spectroscopy have been reported, in which the authors studied, if photostability enhancements were

• (C8F17)2 [36]. These results make it clear that monitoring photoirradiated solutions by UV–vis spectroscopy must be accompanied by complementary analyses to enable accurate interpretation of the changes in the UV–vis spectra and identification of the photoproducts. The next comparative photostability