Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity

• Daria A. Burmistrova,
• Vasiliy A. Fokin,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Maxim V. Arsenyev,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2026, 22, 828–837, doi:10.3762/bjoc.22.65

• distance, indicating the formation of π contacts (Cg···Cg 3.676(9)–3.769(9) Å). In the 1H NMR spectra of all synthesized sulfoxides, the signal corresponding to the proton of the hydroxy group at position 1 of the aromatic ring is significantly shifted downfield relative to that in the corresponding

• thioethers (δ 7.11–7.30 ppm) and appears in the range of δ 11.33–11.85 ppm (CDCl₃; see Supporting Information File 1, Section S2). The signal of the second OH proton is also shifted downfield compared to that in the thioethers (δ 5.53–5.58 ppm) and is observed at δ 6.04–6.17 ppm. In the 13C NMR spectra of

Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against Klebsiella pneumoniae ST512

• Shuo Zhang,
• Ondřej Daněk and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2026, 22, 821–827, doi:10.3762/bjoc.22.64

• repeating unit 20. Synthesis of the analogues 21–24. Supporting Information Supporting Information File 34: Experimental procedures and NMR spectra. Funding We gratefully acknowledge the Max-Planck Society for generous financial support. Conflict of Interest The authors declare no conflicts of interest.

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• molecule displays C2 symmetry, consistent with the simplified NMR spectra, and the solid-state metrics support the proposed pentacyclic structure. Compound 25 (C18H17N4O2 u.d. = 13) has one degree less of unsaturation than the diimine 24 (C18H14N4O2 u.d. = 14) suggesting that a reduction is required for

• structurally complex spirocyclic architectures under mild and operationally straightforward conditions, although the substrate scope appears to be limited. Experimental General remarks: NMR spectra were recorded on a Bruker Nanobay Avance III HD 600 MHz spectrometer. Proton-decoupled. When required, COSY, HMQC

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• additional purification. Reaction mixtures were monitored by TLC using Macherey-Nagel pre-coated TLC-sheets Alugram Xtra SIL G/UV254. For column chromatography Macherey-Nagel Kieselgel 60 was used. NMR spectra of products were recorded with Bruker AV 300, Bruker AV 400, and Bruker DRX 500 spectrometers in

• CDCl3 or (CD3)2CO. NMR samples of the solutions of 4,5- and 1,8-diazafluorenes (6 mg/0.5 mL) for the protonation study were prepared by dissolving 1 and 2 in either pure CD3COOD or CD3OD containing 0.005 mL of CD3COOD. Subsequently, 1H NMR spectra were recorded with a Bruker AV 400 immediately after

• for compounds 1,8-DPDAF, 4,5-DPDAF and Zn–4,5-DPDAF. Acknowledgements The authors acknowledge the Multi-Access Chemical Service Center SB RAS for spectral and analytical measurements. We thank Alena V. Lomanovich for recording time-resolved NMR spectra. Dr. Sergey A. Dobrynin is gratefully

Synthetic study of vic-bromination of diarylacetylenes, easy purification and separation

• Akane Togo,
• Hiyono Suzuki,
• Yuto Akai,
• Makoto Matsumoto,
• Yoshinori Suzuma,
• Hidehiko Kodama and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2026, 22, 795–802, doi:10.3762/bjoc.22.61

• of compounds, and copies of 1H and 13C NMR spectra. Acknowledgements We appreciate Kazuki Miyamoto, Junya Kikuzawa and Ryoichi Tomiyama at Kindai University for useful advice and the cooperation related to this paper. We also thank Akiko Kuwabara and Dr. Masafumi Kobayashi at Kanto Denka Kogyo Co

Halogenated azobenzene acrylates: from efficient solution photoswitching to stable solid-state photochromic materials

• Martina Vachtlová,
• Michaela Fecková,
• Vítězslav Zima,
• Jan Podlesný,
• Milan Klikar,
• Oldřich Pytela,
• Patrik Pařík,
• Jakub Opršal,
• Eliška Juhaňáková,
• Veronika Chrtová and
• Filip Bureš

Beilstein J. Org. Chem. 2026, 22, 782–794, doi:10.3762/bjoc.22.60

• Z → E relaxation at laboratory temperature (20 °C), the and k were measured at 60 °C. The method for its determination is described in our previous article [3]. Figure 7 compares the 1H NMR spectra of the dark-adapted and 355 nm-adapted photostationary states of compound 1e, while Figure 8 show an

• 1d corresponding to the presence of pure Z-isomers. A) HOMO/LUMO localizations in representative E-1a. B) HOMO−1/LUMO localizations in representative Z-1a. 1H NMR spectra (500 MHz, CDCl3, 20 °C) of azobenzene 1e corresponding to the dark-adapted PSS (black) and 355 nm-adapted PSS (violet). A) UV–vis

• electrochemically measured and DFT-calculated data of target azobenzenes 1a–f. Experimentally measured and theoretically calculated optical properties of azobenzenes 1a–f. The E/Z molar ratios, the Z-isomer half-lives and the rate constants of azobenzenes 1a–f determined from the UV–vis and NMR spectra. Supporting

Preparation of 3-(alkylamino)imidazo[1,2-a]pyridine-2-carbaldehydes via Kornblum oxidation and unexpected ring-opening reactions of the corresponding alcohols under oxidative conditions

• Sandile J. Mkhize,
• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2026, 22, 763–770, doi:10.3762/bjoc.22.58

• 8. Yield optimisation using varying amounts of acid catalyst.a Supporting Information Supporting Information File 16: Experimental procedures, copies of NMR spectra and X-ray data of compound 18a. Acknowledgements The authors thank Matthew Bracken for the acquisition of the X-ray data. This work

Synthesis and biological evaluation of new brassinosteroid analogs with C-22 benzoate function

• María Núñez,
• Camila Escobar,
• Mario Párraga,
• Mauricio Soto,
• Luis Espinoza-Catalán,
• Katy Díaz and
• Andrés F. Olea

Beilstein J. Org. Chem. 2026, 22, 753–762, doi:10.3762/bjoc.22.57

• HSQC NMR and 1H,13C HMBC NMR spectra data, respectively (Figures S35 and S36, Supporting Information File 1). Previous studies have shown that Sharpless dihydroxylation of 2,3-steroidal alkenes with OsO4/DHQD-CLB system, leads to formation of "cis" glycols with C-2(R) and C-3(S) stereochemistry in the

• ). Supporting Information Supporting Information File 13: NMR spectra of compounds, biological bioassays and protein–ligand interactions (molecular docking). Supporting Information File 14: Experimental section. Funding Luis Espinoza-Catalán thanks FONDEQUIP (Fondo de Equipamiento Científico y Tecnológico

Rongalite addition to dienones: diastereoselectivity in cyclic sulfone synthesis; stereochemical rationalization and prospects as a general conjugate nucleophile

• Melina Goga,
• Hao Zong,
• James Franco,
• Jazmine Prana,
• Rudolph Michel,
• Antonia Muro,
• Elana Rubin,
• Janet Brenya,
• Henk Eshuis and
• Magnus W. P. Bebbington

Beilstein J. Org. Chem. 2026, 22, 742–752, doi:10.3762/bjoc.22.56

• sulfide oxidation. In that early work, the stereochemical analysis was dependent on conformational analysis and comparison of coupling constants in the 1H NMR spectra. Experiments discussed in our inital report confirmed that the reaction proceeded under kinetic control [21]. Closer examination of the

• . The major product was isolated and assigned as 5 (from axial attack of a small hydride reagent) [24]. From analysis of the NMR spectra of 5, it was clear that the molecule retained symmetry following reduction, reflected in the reduced number of signals in both 1H and 13C spectra compared to alcohol 4

• reaction mixture (≈9:1 ratio by 1H NMR). Evidence for the sterically congested nature of the sulfone 10a was provided by the NMR spectra, which show evidence of restricted rotation (Scheme 3). In the 1H NMR spectrum the signals for the two ortho-methyl groups are inequivalent, and indeed differ in chemical

Anti-invasive and cytotoxic evaluation of a (+)-pinoresinol-based semisynthetic library against glioblastoma

• Chen Zhang,
• Kah Yean Lum,
• Jonathan M. White,
• Paul I. Forster,
• Nicholas Booth,
• Sunita A. Ramesh and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 691–704, doi:10.3762/bjoc.22.54

• melting point apparatus and are uncorrected. Specific rotations were determined on a JASCO P-2000 polarimeter. UV–vis spectra were recorded using a CAMSPEC M501 UV–vis spectrophotometer. ECD spectra were obtained on a JASCO J-1500 spectropolarimeter and processed using the software SDAR [31]. NMR spectra

Synthesis of depressin, cryptomeridiol and 4-epi-cryptomeridiol enabled by a terpenoid chiral pool-producing platform

• Yao Kong,
• Tao Wang,
• Chen Wang,
• Pengcheng Zhang,
• Yuanning Liu,
• Kaibiao Wang,
• Fen Liu,
• Hongli Jia and
• Zhengren Xu

Beilstein J. Org. Chem. 2026, 22, 683–690, doi:10.3762/bjoc.22.53

• ). Supporting Information Supporting Information File 5: Materials, synthetic methods and copies of NMR spectra for all compounds. Supporting Information File 6: X-ray crystal structure of 16. Funding We are grateful to the National Natural Science Foundation of China (No. 82574274) for the financial support.

Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions

• Egor N. Boronin,
• Svetlana E. Kaurkina,
• Milena M. Svetlakova,
• Anton S. Bolshakov,
• Maxim V. Arsenyev,
• Vasilii F. Otvagin,
• Alexey Yu. Fedorov,
• Timothy Noël and
• Alexander V. Nyuchev

Beilstein J. Org. Chem. 2026, 22, 662–671, doi:10.3762/bjoc.22.50

• Information Supporting Information File 2: Experimental part, copies of NMR spectra and computational data. Acknowledgements We thank Dr. Y.B. Malysheva for registration of NMR spectra and S.A. Churkin for technical support. Funding The research was carried out in Laboratory “Chemistry of natural products

Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• Information File 16: Detailed description of the procedure for the gas evolution experiments, NMR spectra of isotopic labeling experiments. Acknowledgements The authors gratefully acknowledge Sasol Technology (UK) Ltd. for GC analyses. Funding The authors gratefully acknowledge the UGent BOF, the Royal

Towards the targeted protein degradation of CK2: design and synthesis of CAM4066-based PROTACs

• Sophie Day-Riley,
• Sona Krajcovicova,
• Aryaman Raj Sokhal,
• Jan L. Venne,
• Paul Brear,
• Marko Hyvönen,
• Benjamin C. Whitehurst,
• Jason S. Carroll and
• David R. Spring

Beilstein J. Org. Chem. 2026, 22, 611–619, doi:10.3762/bjoc.22.47

• = dimethylformamide; HATU = O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate; THPTA = tris(3-hydroxypropyltriazolylmethyl)amine; TFA = trifluoroacetic acid; VHL = von Hippel–Lindau. Supporting Information Supporting Information File 14: Experimental part and copies of NMR spectra

Regioselective approach to 5-arylsulfonylisoxazoles and their antimicrobial activity

• Artem S. Sazonov,
• Dmitry A. Vasilenko,
• Denis V. Porfiriev,
• Yuri K. Grishin,
• Rimma A. Gazzaeva,
• Alisa P. Chernyshova,
• Maxim A. Kryakvin,
• Anna A. Baranova,
• Vera A. Alferova and
• Elena B. Averina

Beilstein J. Org. Chem. 2026, 22, 592–602, doi:10.3762/bjoc.22.45

• 4 hours does the C(4)–H signal of compound 4a at δ 7.05 ppm in the 1H NMR spectra finally disappear. With optimized conditions in hand, we turned our attention to examine the substrate scope. As shown in Scheme 3, isoxazole derivatives bearing different electron-withdrawing groups in position 3 such

• conditions. MIC (μg/mL) against bacterial and fungal lines. Supporting Information Supporting Information File 8: General synthetic and biological procedures, characterization data and copies of 1H, 13C{1H}, 19F, 31P, 1H-13C HSQC, 1H-13C HMBC NMR spectra, HRMS spectra and the results of the elemental

Continuous-flow carbonyl hydrogenation under subatmospheric to atmospheric hydrogen pressure enabled by robust heterogeneous Pt–Fe catalysts

• Hiroyuki Miyamura,
• Ryosuke Kajiyama,
• Shun-ya Onozawa,
• Yoshihiro Kon and
• Shū Kobayashi

Beilstein J. Org. Chem. 2026, 22, 575–582, doi:10.3762/bjoc.22.43

• : Additional experimental details, materials, and methods including photographs of reactor systems, STEM-EDS images and XPS spectra of heterogeneous catalysts, and copies of 1H and 13C NMR spectra for isolated compounds. Acknowledgements H. M. also thanks the Joint Usage/Research Center for Catalysis

Kinetic resolution of racemic planar-chiral vinylcymantrenes by molybdenum-catalyzed asymmetric metathesis dimerization

• Haruna Imazu,
• Hitoshi Izu,
• Yasuhiro Ohki and
• Masamichi Ogasawara

Beilstein J. Org. Chem. 2026, 22, 568–574, doi:10.3762/bjoc.22.42

• substrates rac-1a–c. Molybdenum-catalyzed asymmetric metathesis dimerization/kinetic resolution of racemic vinylcymantrenes 1a–c.a Supporting Information Supporting Information File 19: Experimental procedures, NMR spectra (1H and 13C) for all the new compounds, and chiral HPLC chromatograms. Supporting

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

• to design pharmacological tools in the future. Experimental General information Melting points are uncorrected. Infrared spectra were obtained from solution in 0.1 mm cells or KBr pellets on an FT-IR Mattson 1000 instrument. The 1H and 13C NMR spectra were recorded on 400 (100) MHz Varian or 400 (100

• (τ, °) in the optimized transition states. Supporting Information Supporting Information File 14: Experimental, 1H and 13C NMR spectra for all new compounds, as well as selected 2D NMR spectra and crystallographic data for compound 10 are provided. Optimized geometries of the transition states with

Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• resolution electrospray ionization mass spectrometry (HRESIMS) and NMR spectra. However, the isomeric compound 3 could not be detected in the extract (Figure 1). Since 4 could be an artefact, built by oxidation of 2 during working up of the extract, and to finally confirm the structure, the isomeric

• diacetate (EDDA). However, synthesis of 2 was difficult. Despite numerous attempts, we only were able to get mixtures of both melifoliones with minor amounts of 2. Since all attempts to separate both isomers on a preparative scale failed, we were only able to record NMR spectra from a very small quantity of

• signals detected in the 13C NMR spectrum of 4 (Table 2) could be assigned by careful analysis of the 2D-NMR spectra (HSQC and HMBC). The position of the acetyl group was confirmed by a cross peak between C-2 and the protons of the acetyl-methyl group in the HMBC spectrum and by interactions between the

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

• analysis. Contrary to the 1H NMR spectra, the 19F NMR spectra show significantly fewer characteristic and sufficiently separated signals that allow the unambiguous identification of all photoproducts and, thus, their detection in the course of the photoreaction. Keywords: fluoroarenes; molecular solar

• Information File 1, Figure S16). Contrary to the 1H NMR spectra, the 19F NMR spectra showed significantly fewer signals (one or two per molecule) during the photoreaction because of the symmetry of norbornadiene 1f and its photoproducts and the less complex coupling pattern. Thus, the 19F NMR spectra of the

• circumvented by the application of in situ 19F NMR-spectroscopic measurements. Contrary to the 1H NMR spectra, the 19F NMR spectra are less complex and show characteristic and sufficiently separated signals that allow the unambiguous identification of photoproducts 2f0,3, 2f2,1, and 2f1,2 and, thus, their

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

• ester substrate. When this method was used, the 1H NMR spectra of the products revealed residual peaks corresponding to unreacted ester (Supporting Information File 1, Figure S8). This observation is consistent with the substrate-dependent behavior reported in that study, highlighting that the reaction

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

• reassigning the structure of the cycloaddition reaction product from benzo[c]phenanthridine 1 to benzo[c]acridine 2, we predicted that all three compounds are the benzo[c]acridine isomer 2. The 1H NMR spectra of all three compounds are identical, indicating that they share the same structure (Figure 3A). We

• reported to produce benzo[c]phenanthridine 1, of which the commonly accepted structure of 968 is a member. The structure of the product of this reaction was subsequently reported to be the isomeric benzo[c]acridine 2. A) 1H NMR spectra of compound 968 purchased from Sigma-Aldrich (top), the same compound

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• procedures, characterization data, copies of 1H and 13C NMR spectra, and optimized geometries of DFT calculations. Supporting Information File 26: Crystallographic information file of compound 1ac. Acknowledgements We thank K. Imamura (Evaluation center of material properties, IMCE Kyushu University) for

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

• 1.80 ppm and one triplet at 3.13 ppm were attributed to the remaining methylene protons located near the selenium atom [51]. In the 13C NMR spectra, distinct chemical shift differences were observed between compounds 7 and 8, due to the small structural differences between them. For compound 7, with

• F254). Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Avance 400 MHz FT-NMR and a Bruker Avance III 500 MHz spectrometer. 1H, 13C, and 77Se NMR spectra were acquired in CDCl3, with chemical shifts (δ) reported in ppm. Singlet (s), doublet (d), doublet of doublets (dd), triplet (t

Cone p-aminocalix[4]arenes enriched with ‘clickable’ alkyne or azide functionalities

• Ilia Korniltsev,
• Vasily Bazhenov,
• Alexander Gorbunov,
• Dmitry Cheshkov,
• Stanislav Bezzubov,
• Vladimir Kovalev and
• Ivan Vatsouro

Beilstein J. Org. Chem. 2026, 22, 399–415, doi:10.3762/bjoc.22.28

• tetraureacalix[4]arenes was obtained. Examination of the 1H NMR spectra of the tetraureas in CDCl3 showed that in most cases triazole heterocycles do not intervene the formation of homo- and heterodimeric capsules by these compounds. Thus, considering the synthetic value of CuAAC and amine transformations, p

• calix[4]arene 11 having four TBS-protected propargyl groups at the narrow rim in only moderate yield of 37% [9]. In our hands, according to the NMR spectra of the reaction mixture, under the reported conditions (>30 equiv of fuming HNO3 per calixarene aromatic unit in a 1:1 dichloromethane/acetic acid

• only the reaction time increased (Scheme 2). The 1D NMR spectra for the dinitrocalix[4]arenes 12 and 13 provided no definitive data on the substitution patterns at their wide-rims except for the presence of two nitro groups in the distal aromatic units. To localize the nitro groups in the structures of