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

• {1H} NMR spectroscopy (Figures S1–S20), HRMS (Figures S21–S26) in Supporting Information File 1, and elemental analysis. X-ray data The X-ray suitable crystals of 1a, 4a–7a were grown by slow recrystallization of the compounds from acetonitrile or chloroform (for 7a) solutions at room temperature. The

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

• give 25 as yellow crystals (1.06 g, 6.62 mmol, 67%). Mp = 169.5–170.4 °C; HRMS m/z: [M + H]+ calcd. for [C18H17N4O2 + H]+, 321.1352; found, 321.1358; IR (ATR) ν (cm−1): 3276, 1710, 1619, 1472, 744; 1H NMR (600 MHz, CD3OD) δ (ppm) 7.32 (ddd, J = 7.7, 1.1, 0.6 Hz, 2H, H4’, H4’’), 7.08 (td, J = 7.7, 1.2

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

• about 3 days. The crystals of Zn-4,5-DPDAF (Zn–4,5-DPDAF) were grown by layering a near-saturated ZnCl2 solution in CH3OH over the CHCl3 solution of 4,5-DPDAF. The crystal growth time was about 2 weeks. Single-crystal X-ray diffraction experiments were performed at 296(2) K using a Bruker KAPPA APEX II

• structural data of crystals were deposited as CIF files at the Cambridge Crystallographic Database (CCDC No. 2517007 (4,5-DPDAF), 2517008 (1,8-DPDAF), 2517006 (Zn-4,5-DPDAF)) and can be downloaded freely from the following site: https://www.ccdc.cam.ac.uk. Mercury [33], Olex2, and PLATON [32] were used for

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

• there was an additional proton observed in the aromatic region and one missing from the aliphatic region. Crystals were grown for the unexpected oxidation product formed from 17a and X-ray crystallography revealed that oxidative ring-opening had occurred to give product 18a (Figure 4). Carrying out

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

• planar structure assignment for 5. Moreover, the relative configuration of the semisynthetic derivative 5 was assigned following ROESY data analysis. Following the slow evaporation of a methanolic solution of (+)-eudesmin (3), suitable crystals were obtained for X-ray crystallographic studies (Figure 4

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

• configuration of (–)-2b Levorotatory AMD/KR product (–)-2b, which was obtained as in entry 8, Table 1 using Mo/(R)-L1 precatalyst, was recrystallized by slow diffusion of pentane into the concentrated diethyl ether solution. Crystals of (–)-2b were grown as light-yellow blocks. The X-ray crystallography

Molecular tweezer–peptide conjugates disrupt the protein–protein interaction between survivin and histone H3 essential in mitosis

• Catherine Gsell,
• Philipp Rebmann,
• Karina Opara,
• Christine Beuck,
• Peter Bayer,
• David Bier,
• Ingrid R. Vetter and
• Thomas Schrader

Beilstein J. Org. Chem. 2026, 22, 557–567, doi:10.3762/bjoc.22.41

• interaction by roughly one order of magnitude (from 1 µM to 120 nM Kd). For further structural proof we attempted co-crystallization of survivin with our new tweezer H3 conjugate. Unfortunately, crystallization of full length survivin 1–142 was difficult to reproduce and often resulted in low-quality crystals

• turned to peptide tweezers with longer linkers to address lysines which are buried neither in the crystals nor in the CPC complex. In a second approach, one of the tweezer phosphate groups was truncated to minimize steric hindrance during the tweezer approach towards survivin’s α-helix within the CPC

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

• slightly yellow crystals; mp 60–62 °C. 1H NMR (400 MHz, CDCl3) δ 8.29–8.19 (m, 4H, aromatic), 5.72–5.59 (m, 2H, H-4 and H-5), 5.36–5.27 (m, 1H, H-1), 3.96 (td, J = 9.2, 3.7 Hz, 1H, H-8), 2.60–1.71 (series of m, 8H, CH2); 13C NMR (100 MHz, CDCl3) δ 163.9, 150.8, 135.7, 131.1, 129.5, 128.3, 123.8, 77.7, 64.1

• at room temperature to obtain colourless crystals, mp: 101–102 °C. Compound 11 was recrystallized from the same solvent mixture at 0 °C and obtained as slightly yellow crystals, mp: 117–119 °C. (1S*,2S*,5S*,6S*)-6-Acetoxy-2-azido-5-chlorocyclooctyl 4-nitrobenzoate (10): 1H NMR (400 MHz, CDCl3) δ 8.34

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

• crystals. The high-resolution mass spectrum gave a protonated mol peak at 279.1226 indicating the formula C15H19O5. Compared to melifoliones this means a loss of 3 C-atoms. Based on the NMR spectra (1H, 2D-COSY, 13C, HSQC, HMBC) the structure of the oxidation product was determined as the spirofuranone 11

• mounting of the crystals, all specimens exhibited weak and diffuse diffraction patterns, which significantly limited data quality. This behavior is attributed to poor crystallinity and partial disorder within the crystal, likely exacerbated by the gradual release of solvent molecules during sample handling

• , filtered and evaporated to dryness. The remaining residue was recrystallized from diethyl ether/hexane to give 2.3 g (77%) colorless crystals, containing about 90% melifolione A (1) (CAS: 59779-71-4) and 10% melifolione B (2) (CAS: 37464-54-3), based on the 1H NMR spectrum. NMR data see Table 1 and Table 2

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

• assayed each compound for inhibitory activity against the GAC isoform of glutaminase and found that the three compounds inhibited it with equal potency, further suggesting that the compounds are identical (Figure 3B). To unambiguously determine the structure of this compound, we grew crystals of our

• , 130.92, 129.02, 128.68, 128.12, 127.49, 124.25, 122.93, 120.88, 118.45, 117.59, 116.53, 107.43, 50.77, 44.22, 35.30, 32.80, 29.56, 27.06. X-ray crystallography Crystals of compound 2 were grown by slow evaporation from a saturated acetone solution. A yellow, multi-faceted block of suitable size (0.362

• × 0.124 × 0.064 mm3) and quality was selected from a representative sample of crystals of the same habit using an optical microscope, mounted onto a Mitegen MicroLoopsTM (MiTeGen, LLC., Ithaca, NY) and placed in a cold nitrogen stream of nitrogen. Low temperature (100 K) X-ray data were obtained on a

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

• coupling of compound 1ad with MeMgBr and PhMgBr in the presence of a catalytic amount of NiCl2(PPh3)2 proceeded smoothly to provide the C6-methyl-substituted 1ab in 79% yield and the C6-phenyl-substituted 1ac in 99% yield (Scheme 3) [15][16]. Suitable single crystals were obtained from racemic 1ac, and its

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

• exposure. After adding 1 mg/mL, 100 μL per well of MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide solution, the cells were incubated for 4 hours in a dark area. To dissolve the formazan crystals, 100 μL of DMSO was applied to each well after the media was carefully removed. After 40

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

• calixarene 12, which is additional evidence for its structure. The structure of trinitrated calix[4]arene 16 having a single TBS-protected propargyl group at the narrow rim was unambiguously established from X-ray diffraction data. Suitable crystals were collected upon slow evaporation of a dichloromethane

• /methanol solution of compound 16. Similarly, single crystals of the exhaustively nitrated calix[4]arene 15 having two TBS-protected propargyl groups at the narrow rim were collected, and the molecular structure of this compound was also established (Figure 3) [94]. The results showed clearly, that in

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF

• Ruiyan Wang and
• Yunan Wu

Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16

• , the triplet exciton management and channel selectivity in different phases of PI-Cz 1 were systematically studied, validating the feasibility of “configuration-packing synergy” for controllable RTP–TADF switching within the same molecule. Results and Discussion Single crystals of 1 were successfully

• obtained through the method of slow solvent evaporation, which allows for the formation of high-quality crystals suitable for detailed structural analysis. The crystal structure of 1 was thoroughly characterized using single-crystal X-ray diffraction (CCDC 2492630). This technique provides precise three

• , an in-depth analysis was conducted on both the molecular structure and the packing arrangement in single crystals of 1. As depicted in Figure 6a, the crystal structure of 1 reveals the presence of significant π–π interactions between adjacent molecules. These interactions are crucial for stabilizing

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

• solid form Crystals of 1·HCl were grown from an ethanolic solution, and the crystal structure was determined by single-crystal X-ray diffraction (SCXRD, Figure 2). As seen in Figure 2a, 1·HCl adopts a twisted U shape and is involved in three hydrogen bonds. Therein, the ammonium N atom interacts with

• (4 °C) overnight, the solids were collected by vacuum filtration and dried under high vacuum. In this way, approximately 60% of the starting material was recovered as a white solid. SCXRD Crystals of 1·HCl were grown by slow evaporation of a solution in EtOH at rt. A single crystal suitable for X-ray

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

• 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

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• obtained as a racemic diastereomeric pair 1SR,2RS. Centrosymmetric crystals 9a and 9b are diastereomers and crystallize as a true racemate. The configuration of the chiral atoms C1 and C2 in the molecules is the same as in molecules 2, and the difference is the configuration of atom C3. In crystal 9a, the

• enatiomeric pair S,R,S/R,S,R is realized, and in crystal 9b – S,R,R/R,S,S. The main geometric parameters (bond lengths and valence angles) and the conformation of independent molecules in crystals of 2, 3, 9a and 9b coincide within the experimental errors, so Figures 2–5 show the geometry of one of the

• independent molecules. Note that crystals 2, 3, 9a and 9b have a relatively high density (dcalc/g cm−3 1.739, 1.748, 1.595 and 1.567) for crystals that do not contain heavy atoms. In the absence of hydrogen bonds in the crystals of 2, 3, 9a and 9b, multiple specific interactions of the types such as lone

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

• the OH group. The crystal packing of single crystals 4att, 4atc, 4acc, 4act, 4dct is ordered by intermolecular hydrogen bonds linking O–H groups and heteroatoms O/N of neighboring molecules (see Table S8 in Supporting Information File 1); N–H groups of the hexahydropyrimidine ring and a carbonyl

Synthesis of new tetra- and pentacyclic, methylenedioxy- and ethylenedioxy-substituted derivatives of the dibenzo[c,f][1,2]thiazepine ring system

• Gábor Berecz,
• András Dancsó,
• Mária Tóthné Lauritz,
• Loránd Kiss,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2645–2656, doi:10.3762/bjoc.21.205

• (thickness of the stationary phase: 30 mm, eluent: DCM). After evaporation of the solvent, the residue was triturated with Et2O (50 mL) to give pure 7 (25.30 g, 84%) as colorless crystals. Mp 223‒225 °C (CH3CN/EtOH 1:1 (v/v)); IR (KBr): 1638, 1604, 1574, 1501, 1354, 1300, 1175, 1063, 854 cm−1; 1H NMR (600

• chromatography (short aluminum oxide column, eluent: heptane/DCM 1:1, DCM) and isomer 8 (0.62 g, 2%) was isolated as pale yellow crystals. Mp 254‒256 °C (CH3CN); IR (KBr): 1665, 1485, 1344, 1111, 1061, 859 cm−1; 1H NMR (500 MHz, CDCl3): 7.96 (d, 4J = 2.0 Hz, 1H), 7.94 (d, 3J = 8.6 Hz, 1H), 7.63 (dd, 4J = 2.1 Hz

• -like hard substance obtained was suspended in DIPE to afford 21a as colorless crystals. Mp 76‒78 °C; IR (KBr): 3314, 2939, 1728, 1510, 1328, 1064, 853, 599 cm−1; 1H NMR (600 MHz, CDCl3): 7.94 (d, 4J = 1.9 Hz, 1H), 7.43 (dd, 4J = 2.1 Hz, 3J = 8.4 Hz, 1H), 7.39 (d, 3J = 8.4 Hz, 1H), 6.92 (s, 1H), 6.83 (s

Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• of the desired products. More decisively, a single crystal X-ray analysis was performed. Compounds 3n and 4n were provided with suitable crystals for X-ray structural analysis resulting in new crystal structures, Figure 4 and Figure S250 in Supporting Information File 1, respectively. The single

Ni-promoted reductive cyclization cascade enables a total synthesis of (+)-aglacin B

• Si-Chen Yao,
• Jing-Si Cao,
• Jian Xiao,
• Ya-Wen Wang and
• Yu Peng

Beilstein J. Org. Chem. 2025, 21, 2548–2552, doi:10.3762/bjoc.21.197

• single crystals, and a corresponding X-ray diffraction analysis (inset in Scheme 3, selected H atoms have been omitted for clarity, and Table S3, Supporting Information File 1) unambiguously confirmed its precise structure with three continuous chiral centers. Conclusion In summary, the total synthesis

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• methyl substituents (H2). Fortunately, the X-ray crystal structures of G2W1 and G2W3 reported below shed further light on their poor performance as solid state sequestrants. X-ray crystal structure of G2W1 and G2W3 Eventually, we were able to grow single crystals of G2W3 (CCDC 2466611) and solve their

• crystal structures by X-ray diffraction methods. Figure 5a shows a cross-eyed stereoview of one molecule of G2W3 in the crystal. Crystals of G2W3 are monoclinic with the P21/c space group (a/Å = 10.0768(9); b/Å = 13.4198(11); c/Å = 32.411(3); α/° = 90, β/° = 98.135(3), γ/° = 90). As has been observed

• substituents – provides a compelling explanation for the superior performance of H2 over G2W3 and G2W4. We were also fortunate to obtain single crystals of G2W1 (CCDC 2466610) and solve the structure by X-ray diffraction measurements. Crystals of G2W1 are triclinic with the P−1 space group (a/Å = 15.414(4); b

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• influenced by their tendency to form thermodynamically stable crystals since disruption of such stable structures is more challenging [37][38][39][40][41][42]. Molecules with symmetric elements and plane rings typically tend to form such stable crystals. The notable solubility difference of hydrazones 7a and

• products. 8-(2-Cyclohexylidenehydrazino)-2,4-dimethyl-2H-1,2,3-benzothiadiazine 1,1-dioxide (7e). Prepared according to the general procedure, using 5a and 6e as the starting materials. Yield: 111.0 mg (83%), yellow crystals. Mp 99–100 °C (EtOH); 1H NMR (600 MHz, DMSO-d6) δ 9.19 (br s, 1H), 7.80 (d, J

• to LC–MS). Pure (E)-7h was obtained by purification using flash chromatography (hexane–EtOAc). Yield: 45 mg (40%), colorless crystals. Mp 138–139 °C (EtOH); 1H NMR (600 MHz, DMSO-d6) δ 9.54 (br s, 1H), 7.80 (d, J = 8.6 Hz, 1H), 7.62 (m, 2H), 7.57 (m, 2H), 7.54 (m, 3H), 6.71 (d, J = 7.7 Hz, 1H), 3.47

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• configurations of both natural and synthetic compounds continues to pose a considerable challenge in the life and materials sciences [1]. While X-ray crystallography remains a reliable method for this purpose, the requirement for high-quality single crystals often limits its applicability. In recent years