Experimental and DFT studies on the regioselective methanolysis of 5-azido-9-oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers

• İlknur Polat,
• Selçuk Eşsiz and
• Emine Salamci

Beilstein J. Org. Chem. 2026, 22, 547–556, doi:10.3762/bjoc.22.40

• epoxide ring and acetylation resulted in the formation of two corresponding chloro-acetate isomers. The structure of one of the chloro-acetate isomers was determined via crystallographic analysis and the other by 1D and 2D NMR spectroscopy. DFT computations confirm the regioselectivity of the methanolysis

• ) in pyridine and 4-(dimethylamino)pyridine (DMAP) in 95% yield. Treatment of azido nitrobenzoate 8 with m-CPBA gave a mixture of isomeric epoxides 9a and 9b with a combined yield of 97%. The formation and ratio of these isomers were determined by NMR spectroscopy, showing a 63:37 ratio (1H NMR) of 9a

• combined organic extracts were washed with saturated aqueous NaCl (20 mL) and then dried (Na2SO4). Evaporation of solvent gave the mixture of azidobenzoate epoxides 9a and 9b (1.02 g, 3.07 mmol, 97%), as light brown solid. The formation and ratio of these isomers was determined by NMR spectroscopy, in a 63

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• exemplarily with a trifluorinated trisnorbornadienylbenzene that 19F NMR spectroscopy may be applied as a useful complementary method for the investigation of sequential photoreactions. The trisnorbornadiene core structure was used as it figures as promising scaffold for molecular solar thermal (MOST) energy

• trisquadricyclane. Even though the reaction can be monitored by photometry or by in situ 1H NMR spectroscopy, unambiguous assignment of the distinct intermediate mono- and bisquadricyclanes was not possible because of signal overlap. In contrast, this shortcoming is circumvented with in situ 19F NMR-spectroscopic

• lines, 1H NMR spectroscopy is a very useful method to follow the photoreaction, ideally upon direct irradiation in the NMR probehead (in situ NMR), because it potentially enables accurate structure elucidation. But even though this method may enable the accurate monitoring of a stepwise photochromic

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• using thin-layer chromatography, with the appearance of the characteristic red spot upon treatment with FeCl3 confirming the presence of the hydroxamic acid functionality. Moreover, the formation of the tetra-hydroxamic acid product was confirmed by 1H NMR spectroscopy in deuterated DMSO, as evidenced

Synthesis of a HDAC inhibitor–nanogold probe for cryo-EM visualization in class I HDAC co-repressor complexes

• Wiktoria A. Pytel,
• John W. R. Schwabe and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2026, 22, 480–485, doi:10.3762/bjoc.22.35

• to its corresponding NHS ester 8 and residual starting material was removed by column chromatography. The Boc-protecting group was removed under anhydrous conditions in good yield and the structure of 9 was confirmed by NMR spectroscopy. Compound 9 was maintained as the TFA salt for the final step

Structural reassignment of compound 968, an allosteric glutaminase inhibitor

• Lindsey A. Albertelli,
• Sainabou Jallow,
• Chun Li and
• Scott M. Ulrich

Beilstein J. Org. Chem. 2026, 22, 455–460, doi:10.3762/bjoc.22.33

• anticancer drug target. Compound 968 is a glutaminase inhibitor that is widely used to probe cancer cells’ dependence on glutaminase activity. Here, we show by NMR spectroscopy and X-ray crystallography that the reported benzo[c]phenanthridine structure of compound 968 is incorrect; its true structure is the

Synthesis and anti-cancer activity of naphthalimide–organylselanyl conjugates

• Rajkumar Ravi and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2026, 22, 416–435, doi:10.3762/bjoc.22.29

• compounds, making it a viable alternative for introducing long alkyl chains into selenium-containing systems towards lysosomal membrane permeability (vide supra) [42][43][44]. After synthesis, compounds 7 and 8 were thoroughly characterised using multinuclear NMR spectroscopy ¹H, ¹³C, and ⁷⁷Se NMR

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• configuration of their stereocenters, was determined using NMR spectroscopy and XRD analysis. endo-Isomers 4a–e exhibited the following characteristic signals in their 1H NMR spectra: multiplets in the range of δ 1.5–4.4 ppm were assigned to the protons of the pyrrolizidine ring system. The methyl singlets of

• were established using 1H,13C HSQC NMR spectroscopy. The chemical shift values, signal shapes, and spin–spin coupling constants are provided in Table S1 in Supporting Information File 1. The aromatic protons of compounds 4c–e appear in the downfield region of the spectrum. For product 4c, the aromatic

• endo, −61.3 ppm exo). The structures of all cycloadducts 4a–p were confirmed by 13C DEPT NMR and two-dimensional NMR spectroscopy (HSQC, COSY), supplemented by HRESIMS. Complete spectral data are provided in Supporting Information File 1. The molecular structures of 4b and 4c were also confirmed by XRD

Synthesis of diaryl phosphates using phytic acid as a phosphorus source

• Kazuya Asao,
• Seika Matsumoto,
• Haruka Mori,
• Riku Yoshimura,
• Takeshi Sasaki,
• Naoya Hirata,
• Yasuyuki Hayakawa and
• Shin-ichi Kawaguchi

Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15

• Supporting Information File 24: Experimental section, characterization data and copies of spectra. Acknowledgements We acknowledge the Analytical Research Center for Experimental Science, Saga University, for the NMR spectroscopy and mass spectrometry measurements. We thank Editage (https://www.editage.com

Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH

• Adrian G. Rossebø,
• Hannah G. Kolberg,
• Anders E. Tønder,
• Louise Kjaerulff,
• Poul Erik Hansen,
• Karla A. Frydenvang,
• Jesper Østergaard and
• Jesper L. Kristensen

Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11

• be partially responsible for its high membrane permeability. To investigate if an IMHB is indeed present in 1, we combined DFT calculations with NMR spectroscopy titrations. For a system containing an IMHB, it would be expected that replacing the proton (O–H) with a deuteron (O–D) would lead to an

• approach [30]. To ensure gauge independence, nuclear shielding was calculated using the GIAO approach [31][32]. NMR spectroscopy NMR spectra were acquired on a 600 MHz Bruker Avance III HD spectrometer equipped with a 5 mm DCH cryoprobe at 300 K unless otherwise specified. Spectra were processed using

Design and synthesis of an axially chiral platinum(II) complex and its CPL properties in PMMA matrix

• Daiki Tauchi,
• Sota Ogura,
• Misa Sakura,
• Kazunori Tsubaki and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2026, 22, 143–150, doi:10.3762/bjoc.22.7

• platinum(II) complexes with pincer ligand moieties [12]. Thus, the reaction of S/R-3 with platinum(II) precursor 4 in the presence of CuI and diisopropylamine afforded the target platinum(II) complex S/R-Pt in moderate yield. The identification of the complex S/R-Pt were carried out with 1H and 13C NMR

• spectroscopy, as well as high-resolution mass spectrometry (HRMS). Due to its low solubility, single crystals suitable for X-ray crystallographic analysis could not be obtained. Spectroscopic analysis and DFT calculations To elucidate the electronic structure of the platinum(II) complex, UV–vis absorption

Sustainable electrochemical synthesis of aliphatic nitro-NNO-azoxy compounds employing ammonium dinitramide and their in vitro evaluation as potential nitric oxide donors and fungicides

• Alexander S. Budnikov,
• Nikita E. Leonov,
• Michael S. Klenov,
• Andrey A. Kulikov,
• Igor B. Krylov,
• Timofey A. Kudryashev,
• Aleksandr M. Churakov,
• Alexander O. Terent’ev and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2025, 21, 2739–2754, doi:10.3762/bjoc.21.211

• washed with CH2Cl2 (3 × 20 mL). The combined organic phase was washed with H2O (20 mL) and brine (20 mL), dried over Na2SO4, and the solvent was removed in vacuo. The yields of 2a were determined with the use of 1H NMR spectroscopy using 1,1,2,2-tetrachloroethane as an internal standard. NMR and IR

• anodic and cathodic compartments were separately evaporated under water-jet vacuum. The yield of 2a was determined according to 1H NMR spectroscopy using 1,1,2,2-tetrachloroethane as an internal standard. Reaction under constant potential electrolysis (experimental details for Scheme 4, reaction 2): In a

• under magnetic stirring. After passing 2.0 F per mol 1a of electricity, electrodes were washed with CH2Cl2 (3 × 20 mL). The combined organic phase was washed with H2O (20 mL) and brine (20 mL), dried over Na2SO4, and solvent removed in vacuo. The yield of 2a was determined according to 1H NMR

Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones

• Svetlana O. Kushch,
• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess,
• Pavel A. Slepukhin,
• Alexandrina S. Volobueva,
• Vladimir V. Zarubaev and
• Victor I. Saloutin

Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209

• octahydropyrido[1,2-a]pyrimidinones 4a–d and hexahydrooxazolo[3,2-a]pyridones 5a–c was determined by IR, 1H, 19F, 13C NMR spectroscopy, two-dimensional NMR experiments, and X-ray diffraction analysis (XRD). The IR spectra of octahydropyrido[1,2-a]pyrimidinones 4a–d are characterized by reduced vibrational

• three nucleophilic centers in 1,3-diaminopropan-2-ol (3), and because there is a need to increase diastereoselectivity of the cyclization process. Table 1 presents the optimization steps for the reaction conditions at various solvents and temperature. The reaction course was monitored by TLC and 19F NMR

• spectroscopy. In all the four solvents used, both types of products were formed: octahydropyrido[1,2-a]pyrimidin-6-one as four diastereomers 4att (δF 79.52 ppm), 4atc (δF 79.61 ppm), 4acc (δF 79.91 ppm), 4act (δF 80.02 ppm); and hexahydrooxazolo[3,2-a]pyridin-5-one as two diastereomers 5atc (δF 79.66 ppm) and

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• 19 was moderate because the anomeric carbon at C7 is associated with an acid-sensitive acetonide group. The structural determination of the major product 19a was accomplished by comprehensive NMR spectroscopy and further unambiguously confirmed by X-ray analysis (see Supporting Information File 1 for

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• thiophene, promoting further study of these structures and reaction mechanism. 1H NMR spectroscopy of the obtained mixture provided the first key information about its nature, namely the presence of two major products 2 and 3, both of which showed three characteristic singlets with signal integration 1:3:3

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• thoroughly characterized by 1H and 13C NMR spectroscopy, HRMS, and single-crystal X-ray diffraction analysis (Figure 1). A range of solvents was subsequently screened; however, none provided an improvement over 1,4-dioxane for this transformation (Table 1, entries 2 and 3). In addition to AgNO3, other silver

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• determined by 1H NMR spectroscopy. (A) Conformers arising during the rotation around the C5–C6 bond in pyranosides. (B) Furanoside ring conformers of monosaccharide 2 in the pseudorotation diagram. The dashed colored circles denote the initial conformations taken for optimization. Solid colored circles

Halogenated butyrolactones from the biomass-derived synthon levoglucosenone

• Johannes Puschnig,
• Martyn Jevric and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175

• fluorination attempts. Maintaining some residual solvent allowed for the characterization of compound 13 by NMR spectroscopy. Stereochemical assignment in 13 was based on a large trans-axial coupling constant JH2exo-H3 = 10.6 Hz in the 1H NMR spectrum and interactions between H3endo and H7endo on the

Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid

• Yana I. Sakhno,
• Oleksander V. Buravov,
• Kostyantyn Yu. Yurkov,
• Anastasia Yu. Andryushchenko,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158

• control of the reaction, while oxygen-bridged heterocycles 4 are formed under thermodynamic control. The purity and structure of compounds 4 and 5 were established by elemental analysis, mass spectrometry, 1H and 13C NMR spectroscopy, and X-ray diffraction study (Figure 1). For example, the 1H NMR spectra

α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• and 13C NMR spectroscopy, and by X-ray diffraction study (see Experimental part). The 1H NMR spectra of compounds 5 are characterized by the following signals: a broad carboxyl group proton singlet at 12.10–12.17 ppm, an NH group proton singlet at 7.74–8.02 ppm, an aromatic protons multiplet at 6.52

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• and 1.2 equiv 2,6-(t-Bu)2Py in EtOAc gave the styryl side chain-containing tetrahydrofuran 8a with 82% NMR yield after 3 h at 60 °C (Table 3, entry 2). The formed double-bond geometry in product 8a was proved by the 2D-NOESY spectrum. The corresponding (Z)-isomer was not detected by NMR spectroscopy

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• = 4,4′-di-tert-butyl-2,2′-dipyridine) as a photocatalyst and the simple tertiary amine diisopropylethylamine (DIPEA, 5 equiv) in MeCN (0.05 M). After 24 h under irradiation with light from blue LEDs (λmax = 440 nm), the crude mixture was concentrated under reduced pressure and analyzed by 1H NMR

• spectroscopy. As shown in Figure 2, complete consumption of 1 was observed under these conditions with concomitant formation of a major new species with a characteristic 1H NMR signal at δ = 4.42 ppm (in CDCl3, Table 1, entry 1). Comparison of the spectrum with that of an authentic sample (see Supporting

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Single crystals suitable for X-ray diffraction measurements of compounds 3a, MC2, and MC3 were successfully obtained to reveal their molecular structures. In the crystal structure of 3a (Figure 2a), the two pyrene units are nearly

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• extracted three times with CH2Cl2. The combined organic layers were dried over Na2SO4, filtered and concentrated under vacuum. Yields were calculated on the reaction crude by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. In the case of the large-scale reaction the crude was

• /cm2), total charge 2.2 F/mol, dry DMF (0.125 M). Yields reported are isolated yields. Reactions were performed on a 0.5 mmol scale. Continuous flow synthesis of piperazine 2a. The yield was determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as internal standard. Reactions were performed

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• leaving group and activated, electron-poor dipolarophiles has been reported [31][32]. Treatment of aldehyde 4 with hydroxylamine in toluene at 60 °C for 1–3 h resulted in loss of the aldehyde as judged by 1H NMR spectroscopy of the crude mixture. When this was carried out in the presence of N

• -methylmaleimide with the mixture being heated under reflux for 3–4 h, we were pleased to obtain the spirooxindole product 5, which was formed as a mixture of stereoisomers (Scheme 3). The ratio of isomers was determined by 1H NMR spectroscopy and the major isomer could be isolated after careful column

• fumarate was also successful and gave a mixture of the stereoisomeric cycloadducts 7 (Scheme 5). The yield was high and three inseparable stereoisomers could be detected by 1H NMR spectroscopy. In each case we assume that the methyl ester groups are trans to one another due to the expected concerted nature

Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction

• Pricilla Matseketsa,
• Margret Kumbirayi Ruwimbo Pagare and
• Tendai Gadzikwa

Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144

• respective isocyanate in acetonitrile at 80 °C; KSU-1 reacted with isopropyl, tert-butyl, n-hexyl, and tetradecyl isocyanate to generate KSU-1iPr and KSU-1t-Bu, KSU-1n-Hex, and KSU-1C14, respectively. Successful post synthetic reaction was observed by proton nuclear magnetic resonance (1H NMR) spectroscopy