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

• -ray analysis (Figure 2) [25]. X-ray analysis of azido compound 10 confirmed the trans configuration of the azide group with chloride and the cis configuration with the acetate. Our suggested mechanism for the ring-opening of the epoxides 9 with HCl(g) in MeOH proceeded as described in Scheme 3. As

• NOESY experiments or the other 2D NMR conducted. Compound 11 is not a single crystal, so the determination by X-ray analysis of its structure was not possible. We strongly assume that the structure of 11 is based on the methanolysis mechanism of the epoxide 9a (Scheme 3). In order to elucidate the

• selected interatomic distances and cartesian coordinates for computed structures. Acknowledgements The authors would like to thank Professor Ertan Sahin for performing the X-ray analysis. Funding This study was funded by the Research Fund of the Atatürk University (project number: 2014/54). The authors

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

• contraction of the acetyl phenol to a furanone ring, forming the derivatives 11 and 12, whose structures were confirmed by X-ray analysis. A hypothetical mechanism for the oxidative ring contraction is proposed. 11 and 12 are the first representatives of new heterocyclic ring systems that have not previously

• could be clarified by NMR spectra and complex X-ray-analysis of a mixture of structural isomers in the elementary cell. The importance of our results lies in the fact that it could open the door for future attempts to achieve enzymatically catalysed oxidation of the isomeric melifoliones to obtain the

• %), which solidified after some time (mp 153–154°C). HRESIMS m/z: [M + H]+ calcd. for C15H19O5, 279.1227; found, 279.1226; NMR-data see Table 3. TLC on silica gel 60 F254 plates with hexane/dichloromethane/ethyl acetate (10:8:2): fR = 0.15, compared to 1 and 2 with fR = 0.48. For X-ray analysis, compound 11

Synthesis of tricyclic fused pyrrolidine nitroxides from 2-alkynylpyrrolidine-1-oxyls

• Mark M. Gulman,
• Yuliya F. Polienko,
• Sofia Yu. Trakhininа,
• Yuri V. Gatilov,
• Tatyana V. Rybalova,
• Sergey A. Dobrynin and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2026, 22, 344–351, doi:10.3762/bjoc.22.22

• protons of the dimethylamino group and the methylene protons of the propargyl moiety. The structure of nitroxide 2d was confirmed by single crystal X-ray analysis. (Figure 1, CCDC 2512649). The nitroxides 2a–f were used to synthesize tricyclic nitroxides 4a–f. The mesylation was carried out in the

• protocols, copies of the 1H NMR, IR and EPR spectra and X-ray analysis data. Supporting Information File 4: Crystallographic information of selected compounds. Acknowledgements The authors thank the personnel of the Multi-Access Chemical Research Centre SB RAS for having recorded IR, UV, NMR and HRMS

Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene

• Dmitry N. Platonov,
• Alexander Yu. Belyy,
• Rinat F. Salikov,
• Kirill S. Erokhin and
• Yury V. Tomilov

Beilstein J. Org. Chem. 2026, 22, 64–70, doi:10.3762/bjoc.22.2

• excellent yield, the structure being confirmed using single crystal X-ray analysis (CCDC 2495984). Bromination afforded a mixture of symmetric cycloheptatriene 4b and norcaradiene 6b, while intermediate cycloheptatriene 5b was not even observed. Iodination gave exclusively norcaradiene 6c. Previously

• norcaradiene product in the case of benzylation, unlike in the close analogues, is due to a steric repulsion. The structure of norcaradiene 6f was confirmed through single crystal X-ray analysis (CCDC 2495985). Allylation of anion 2 was followed by intramolecular [4 + 2]-cycloaddition in norcaradiene 6g to

• form caged tetracyclodecene 7g similar to that previously obtained from anion 1 [17] and also confirmed through single crystal X-ray analysis (CCDC 2496140). Using aryldiazonium salts as electrophiles afforded an even more complicated cascade process. Initial reactions with phenyl- or 4-substituted

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

• structure of 2c was confirmed by single-crystal X-ray analysis. The benzyl moiety was also tolerated, and the corresponding product 2e was obtained in 57% yield. 2,2-Dimethyl-5-nitro-5-nitroso-1,3-dioxane (1f) was successfully employed under the reaction conditions, leading to the formation of product 2f in

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

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

• the Baeyer–Villiger reaction. Supporting Information Supporting Information File 14: Experimental procedures and compound characterization data. Acknowledgements We thank Dr. Min Shao (Shanghai University) for assistance of X-ray analysis. Funding Financial support from the National Natural Science

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

• rate of evaporation from a nanolitre solution of analyte encased within oil [33], suitable single crystals were obtained. The X-ray analysis allowed the determination of the relative stereochemistry, as shown in Figure 2. Compound 5a crystallised as a racemic mixture in the space group P21/c. The major

[3 + 2] Cycloaddition of thioformylium methylide with various arylidene-azolones in the synthesis of 7-thia-3-azaspiro[4.4]nonan-4-ones

• Daniil I. Rudik,
• Irina V. Tiushina,
• Anatoly I. Sokolov,
• Alexander Yu. Smirnov,
• Alexander R. Romanenko,
• Alexander A. Korlyukov,
• Andrey A. Mikhaylov and
• Mikhail S. Baranov

Beilstein J. Org. Chem. 2025, 21, 1791–1798, doi:10.3762/bjoc.21.141

• relative configuration (cis or trans) of the substituents. Therefore, the structures of the obtained compounds were determined by single crystal X-ray analysis (Figure 1). Thus, all the obtained derivatives of oxo-rhodanine 6, rhodanine 8 and imidazolone 9 had a cis configuration, while the derivatives of

• would be of help in further drug design of spirocyclic scaffolds. Single crystal X-ray analysis for the compounds 6e (A), 7d (B), 8e (C) and 9e (D). Atoms are shown as thermal ellipsoids at 50% probability. All hydrogen atoms, except the one at the stereogenic center, are omitted for clarity. Synthetic

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• ). The structure of Me-M16 was additionally verified by single-crystal X-ray analysis (the enantiomeric compound (R)-Me-M16 resulting from a separate synthesis was crystallized, see Figure 4). Due to the macrocyclic structure, the two ethylene glycol units directly attached to each dimethylphenyl linker

Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides

• Tsun-Yi Chiang,
• Mei-Huei Lin,
• Chun-Wei Chang,
• Jinq-Chyi Lee and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131

• biomolecules in organisms. However, the R/S stereochemistry of pyruvate ketal is difficult to control through chemical methods. In this study, the acid-labile pyruvate ketal linked to the 4- and 6-positions of galactose was cautiously constructed, and the X-ray analysis of the R-configured product was

• pattern aligns with existing literature and is corroborated by our X-ray analysis. High-resolution electrospray ionization mass spectrometry confirmed the molecular mass, showing spectral peaks aligning with the calculated mass ([M + Na]+ calcd for C72H78N4O23Na, 1389.4949; found, 1389.4943). Conclusion

Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer

• Yusuke Matsuo,
• Aoi Nakagawa,
• Shu Seki and
• Takayuki Tanaka

Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119

• characterized by X-ray analysis and NMR spectroscopy at elevated temperatures. Optical studies showed that compound 4 had broad absorption (up to 450 nm) and emission at 546 nm, while macrocycle 5 showed an emission peak at 528 nm, presumably as a consequence of structural relaxation and CT character. This

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• derived from 5-mercapto-1H-tetrazoles was also examined. Keywords: 2,5-dihydro-1,3,4-thiadiazoles; enolizable 5-mercapto-1H-tetrazoles; insertion reactions; thiiranes; thiocarbonyl ylides; X-ray analysis; Introduction Cycloaddition reactions, including 1,3-dipolar cycloadditions, are considered as one

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• was generally accepted that this cyclic ether is planar but this myth was eventually debunked by Luger and Buschmann in 1984 who carried out the first X-ray analysis of oxetane [2] and calculated a small puckering angle of 8.7° at 140 K, which is much smaller than the approximate 30° puckering angle

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

• % yield. Based on X-ray analysis data the synthesized compound 4a is 2H-furo[3,2-b]pyran-2,7(3H)-dione bearing an enamine fragment at the furanone ring (Scheme 2b). It’s interesting to note that prepared product 4a exists in form of the Z-isomer. This configuration is apparently stabilized by an

• established by X-ray analysis. The proposed mechanism of the considered processes is outlined at Scheme 8. Initially, the free nitrogen nucleophile is reversibly generated from the corresponding hydrochloride or acetate. Next, acid-catalyzed addition of the amine component to the carbon atom of the aroyl

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

• CH3CN.a Supporting Information Supporting Information File 11: Experimental procedures and characterization data for all novel compounds 7a, 7b, 8a and 8b. Supporting Information File 12: 1H, 13C NMR, IR and HRMS spectra of all novel compounds. Supporting Information File 13: X-ray analysis data of 7b

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• benziodoxolone, 2d) were obtained with quantitative yields, as white solids on the gram-scale, easy to manipulate and long-term stable below 0 °C. Crystals of compound 2d were successfully obtained and its molecular structure was confirmed through single-crystal X-ray diffraction. The X-ray analysis revealed a

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• ) was prepared to grow single crystals suitable for X-ray analysis (Scheme S2 in Supporting Information File 1) in order to confirm the annulation reaction pattern, and 2,3,6,7-tetrakishexyloxy-10-phenyltriphenylene (BTP6, Scheme S3), the non-fluorinated isomer of F6 and PH6 (Figure 1), for probing the

• analysis (Figures S1–S32, Supporting Information File 1), and all the results agree with the proposed molecular structures. Single-crystal structure of F Suitable single crystals of compound F for X-ray analysis were obtained by slow evaporation of an ethyl acetate/ethanol solution (Figure 2, and

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• Supporting Information File 30: Experimental procedures, product characterization, X-ray analysis and copies of NMR spectra. Acknowledgements The authors gratefully acknowledge Central Glass Co. for the gift of trifluoro- and difluoroacetaldehyde hemiacetal.

Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

• Jón Atiba Buldt,
• Wang-Yeuk Kong,
• Yannick Kraemer,
• Masiel M. Belsuzarri,
• Ansh Hiten Patel,
• James C. Fettinger,
• Dean J. Tantillo and
• Cody Ross Pitts

Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259

• for the first time created an opportunity for structural analysis. We previously reported and contextualized single-crystal X-ray diffraction (SC-XRD) data on 2 [36]; thus, we proceeded to grow crystals of 3 suitable for X-ray analysis through slow evaporation of ethyl acetate. To our surprise, an

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• single-crystal X-ray analysis were obtained by slow evaporation of a dichloromethane/isopropanol solution of 3b. The crystal structure of 3b, displayed in Figure 4, shows a very similar twisted conformation of the core of the molecule to that of the related methoxy-substituted structure obtained from

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• analysis, mass spectrum, and IR are consistent with the structure (for details see Supporting Information File 1). Finally, a single crystal X-ray analysis of compound 6a was performed, confirming the structure (Figure 4). The proposed mechanism for an isocyanide-based multicomponent domino reaction for

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• , borylation of a dodecasubstituted porphyrin’s meso-phenyl position was explored and a subsequent C–C coupling showed the polarity of the reaction can be reversed resulting in higher yields. X-ray analysis of the target compounds revealed the formation of supramolecular assemblies, capable of accommodating

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• radical-involved mechanism. In addition, a positive nonlinear relationship between the product and ligand indicated that the dinuclear copper is the active catalyst, which was also proved by single crystal X-ray analysis. However, kinetic experiments showed the reaction is first-order on copper, implying

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

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

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• purification. The synthetic utility of the prepared tetronic acids was demonstrated by further transformations at the hydroxyethylidene fragment. The structures of one obtained tetronic acid and one product of derivatization were confirmed by X-ray analysis. Keywords: allomaltol; base-promoted recyclization

• refluxing EtOH allowed us to obtain substituted enehydrazine 7 (Scheme 5a). The similar condensation with amine 8 led to enamine derivative 9 (Scheme 5b). Based on the data of X-ray analysis compound 7 has the same configuration of double and hydrogen bonds as in the case of starting tetronic acids 4

• purification procedure are the advantages of the considered method. The synthetic utility of obtained tetronic acids was demonstrated by preparation of enamine and enehydrazine derivatives. The structures of one target tetronic acid and synthesized enehydrazine were established by X-ray analysis. Experimental