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

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• molecular platforms in various applications, such as circularly polarized luminescence (CPL) materials, chiral liquid crystals and asymmetric catalysis. Currently, the asymmetric catalytic synthesis of helicenes predominantly revolves around transition metal-catalyzed asymmetric annulation reactions

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

• , it is no surprise that PSM is a prevalent method for synthesizing MOF-based catalysts [30]. On this topic, our current work was inspired by Canivet et al. who previously reported the lipophilization of a MOF by grafting long alkyl chains to the external surfaces of its crystals. The active sites are

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• , Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama 337-8570, Japan 10.3762/bjoc.21.138 Abstract In single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one and the thione analogue, a unique association based on a halogen–π interaction was detected. In racemic and optically pure

• ; single crystals; thiones; Introduction In the past several years, C–N atropisomers (C–N axially chiral compounds) owing to the rotational restriction around a C–N single bond have received great attention as new target molecules for catalytic asymmetric reactions. Highly enantioselective syntheses of

• the single crystals of racemates significantly differs from that of optically pure forms (chirality-dependent halogen bonding, Figure 1) [20][21]. That is, in crystals of racemic mebroqualone rac-I, heterochiral zig-zag polymer chains, in which (P)-I and (M)-I were alternately connected, were formed

Thermodynamics and polarity-driven properties of fluorinated cyclopropanes

• Matheus P. Freitas

Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137

• insights can guide the prediction of molecular properties, paving the way for the design of innovative applications. Fluorinated cyclopropanes, with their unique electronic and structural characteristics, hold significant potential in the development of new drugs, advanced materials like liquid crystals

• delocalization interactions. Among the compounds shown in Figure 1, 1.2.3-c.c. is the most polar, with a calculated dipole moment of 4.17 D. Polarity is a key molecular property, as it influences solubility, lipophilicity, and various material characteristics. For example, liquid crystals used in LCD devices

• development of liquid crystals, ion carriers, and other technologies dependent on precise molecular properties. Computational Details The fluorinated cyclopropanes shown in Figure 1 were optimized using density functional theory (DFT) at the B3LYP-GD3BJ/6-311++G(d,p) level [20][21][22], which includes

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

• and 8.98 ppm and five doublet signals due to the heterole β-protons in the range of 6.7–5.8 ppm, along with o-phenylene protons around 7 ppm. Single crystals suitable for X-ray diffraction analysis were obtained from a mixture of acetone/n-hexane and the solid-state structure was successfully

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

• analysis (Figure 1a and Figure 1b, respectively). Single crystals of 9i and 10i were obtained by slow evaporation from a hexane/CH2Cl2 solution and subsequently used for crystallographic X-ray measurements. In the case of 9i, the molecule is strongly disordered in the outer carbon ring regions. However

• (9a and 10m) or from MeOH (10c). Analytically pure samples of products isolated after chromatography were prepared after recrystallization from hexane/CH2Cl2 mixture. 1-Methyl-4-[2-(methylthio)adamantan-2-yl]-1,4-dihydro-1H-tetrazole-5-thione (9a): Yield 97 mg (66%), colorless crystals; mp 107‒109 °C

• . calcd for C13H20N4S2 (296.45): C, 52.67; H, 6.80; N, 18.90; S, 21.63; found: C, 52.63; H, 6.92; N, 18.81; S, 21.74. 2,2,4,4-Tetramethyl-3-[(1-methyl-1H-tetrazol-5-yl)thio]-3-(methylthio)cyclobutan-1-one (10c): Yield 120 mg (84%); colorless crystals; mp 136‒138 °C (MeOH); 1H NMR (CDCl3) δ 1.50 (s, 6H

High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters

• Kelsey Plasse,
• Valerie Wright,
• Guoshu Xie,
• R. Bernadett Vlocskó,
• Alexander Lazarev and
• Béla Török

Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102

• compounds are expected to form crystals of higher density, compared to their liquid state. However, phase transitions of the vast majority of organic compounds at high pressure are not yet adequately studied. Data on their behaviour when pressurized are not readily available, except for some long chain

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

• non-benzenoid nanographene 34 [45]. Single crystals of 34 surprisingly exhibit SHG-CD (second harmonic generation–circular dichroism) properties due to the unusual self-sorting of R and S enantiomers in the crystalline state. Scholl-type oxidation: The Scholl oxidation is a highly useful tool for

Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• LiAlH4 in ether to form alcohol 40 (89%) (Scheme 3). The primary alcohol 40 was then converted to its iodide derivative 42 (89%), from which single crystals were obtained, and its structure was determined unequivocally by XRD crystallography. Iodide 42 was then reacted with sodium phenylsulfinate in DMF

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• undescribed amine analogues 2–15 were fully characterised following 1D/2D NMR, UV, and HRMS data analyses. X-ray crystallographic analysis of crystals obtained from the aminated products 2, 7, 10, and 15 are also reported here. The new library of amine-substituted triazolopyrazines was screened against the

• with relevant position numbering. Crystals obtained for 2 were analysed by X-ray crystallographic studies and confirmed the NMR-based structure assignment. The crystal structure of 2 is shown as a thermal ellipsoid plot below (Figure 3). With a simplified approach for the synthesis of aminated

Gold extraction at the molecular level using α- and β-cyclodextrins

• Susana Santos Braga

Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89

• expected tridimensional CD-MOF in the presence of KAuBr4 in aqueous solution. Instead, they self-assembled into unidimensional threads that aggregated into superstructures and formed, in less than one minute, needle-shaped crystals visible to the naked eye. In these crystals, the molecules of α-CD stacked

• diffraction of single crystals (Figure 3), showing, for both 1:1 and 2:1 stoichiometries, cyanoaurate anions inside the host cavity and potassium cations interacting with hydroxy groups of adjacent cyclodextrins. The strong host–guest affinity and complex stability in the solution phase has been studied by

• added to reach a final concentration of 0.25% (v/v). To better understand the role of DBC, crystals of the ternary complex β-CD·KAuBr4·DBC were obtained by slow vapor diffusion of DBC into an aqueous solution of KAuBr4 and β-CD over three days. Single-crystal diffraction showed the [AuBr4]− anion

Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• further understand the complexation with metal cations, separate co-crystals of HIM 1 with LiBArF20 and NaBArF24 were obtained by vapor diffusion of diethyl ether into acetone. The details of the co-crystallization experiment are provided in the crystallographic information section of Supporting

• Information File 1. Single crystals with quality suitable for XRD analysis were obtained in both cases (Figure 5). Unlike the previous assumption of metal coordination at the macrocycle core [17], the crystal structures reveal complexation of both cations at the periphery of the macrocycle. Both 1/LiBArF20

• similar trend was seen in the HIM–Na+ crystals where complex 4 and complex 5 are similar in energy with a difference of less than 1.5 kJ/mol. While both Li+ and Na+ crystals were prepared in similar conditions, the difference in the resulting crystal structure (e.g., location of benzyl rings) could arise

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• target ultracyclic hosts. The synthesized ultracycles were fully characterized by spectrometric and elemental analysis (Scheme 1 and Schemes S1‒S3 in Supporting Information File 1). Single crystals of B4aH were obtained by slow vapor diffusion of ethyl ether into an acetonitrile/chloroform 1:1 (v/v

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

• understand cooperative interactions between complexed ions, we tried to grow the crystal structure of studied salts. Fortunately, single crystals of Cs2CO3 and Cs3PO4 complexes were obtained by slow vapor diffusion from acetonitrile and diethyl ether. Notably, clearly stronger ion-dipole interactions of

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• conditions. The product was isolated as colorless crystals in good yield of 81% (Scheme 1). Complex 4 crystallizes as a C2-symmetric chiral mononuclear complex in which Ca is bound to two monodentate phosphate ligands (Figure 1). Four MeOH ligands complete the slightly distorted octahedral coordination

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

• hydrophobic region of the guest which changes the orientation of Ha with respect to the magnetically shielding region [54][63][64]. X-ray crystal structure of C1 We were fortunate to obtain single crystals of the C1·Me6CHDA complex and solved the crystal structure by X-ray diffraction (CCDC 2411723). Figure 5

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

• stereoelectronic effects such as hyperconjugation and electrostatic attraction/repulsion. These fluorine-derived conformational effects have been exploited to control the shapes, and thereby enhance the properties, of a wide variety of functional molecules including pharmaceutical agents, liquid crystals

• stereochemical change can have upon physical properties. Another functional context in which multivicinal fluoroalkanes have been explored is in liquid crystals [8][40]. Liquid crystalline materials require the molecules to be rod-shaped, and to have a dipole moment that is oriented perpendicular to the long

• molecular properties. The fluorine–oxygen gauche effect has been exploited to influence the properties of liquid crystals [86][87]. For example, the vicinal fluoroether 50 (Figure 7) can adopt a low-energy conformation in which the terminal C–F bond aligns gauche to the vicinal C–O bond. This orientation of

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

• processes contributing to the low fluorescence quantum yield of the F8-phenacenes (cf. Table 1). Because fluorescence behavior in the solid state reflects molecular alignment and intermolecular interactions in the crystals, solid-state fluorescence of the F8-phenacenes was investigated. We observed

Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters

• Olesja Koleda,
• Janis Sadauskis,
• Darja Antonenko,
• Edvards Janis Treijs,
• Raivis Davis Steberis and
• Edgars Suna

Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50

• NMR methods, and all attempts to obtain crystals suitable for X-ray crystallographic analysis were unsuccessful. N-Protected 2-aminoproline derivatives 6 are relatively stable under basic conditions as evidenced by successful hydrolysis of the ester moiety in 6a,d,e using aqueous LiOH to provide acids

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

• colorless crystals from the reaction between Et3N and CH2Cl2 at 100 °C in DMF. Subsequently, the corresponding α-aminophosphonate 35a was obtained by heating 36a with an equal amount of diethyl phosphite (Scheme 28b). Furthermore, when the reaction was carried out with CD2Cl2, the corresponding deuterated

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

• crystals, addition of a drop of 1,2-dibromoethane). Only the addition of 1,2-dibromoethane enabled the generation of the Grignard reagent which was observed by bubbles and an instant increase of the reaction mixture’s temperature. CF2C6F5I (97.5 µL, 625 µmol) dissolved in dry THF (20 mL) was added with a

• concentrations used for ANTH, 9,10-ANTH(BnF)2, and quinine sulfate were 1.89, 1.14, and 1.94 (10−5 M), respectively. Relative quantum yields were calculated using the following equation referenced to quinine sulfate (Φf = 0.55 in 0.1 M H2SO4): X-ray crystallography The diffraction-quality single crystals of 9

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• packing mode. Extra precautions were taken to shield the compounds from light during synthesis, purification, and storage. After crystallizing each bimane, a vial containing multiple crystals was selected for irradiation studies. Cl2B (B), which showed 5% presence of the [2 + 2] dimer after

• ). Crystallographic bond length restraints and constraints were used in each model and bond lengths and angle accuracy are affected by the disorder model (see Supporting Information File 1 for further details). In the case of Cl2B (all crystals, Figure 5), the torsion angle between the two double bonds in the bimane

• fluorescence spectrum and η is the refractive index of the solvent. Single crystal X-ray diffraction studies Crystals of Me4B, Cl2B (A), (B), (C), and Me2B were mounted on a MiTeGen micromount with NVH immersion oil. Data were collected from a shock-cooled single crystal at 100(2) K on a Bruker Apex Kappa Duo

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• studied to get insights into the impact of light energy onto crystals [60][61]. In the following, we describe selected examples with an emphasis on the role of manual grinding in improving irradiation. Mechanochemistry is a linchpin in topochemical solid-state reactions, where the correct molecular

• spectroscopy (Scheme 1). During the reaction progress, the C=C bonds of bpe ligands undergo pedal-like motion prior to photodimerization [63]. For the single-crystal irradiation, the slow reactivity can be attributed to the hindered pedal motion in the single crystals, likely due to the presence of

• coordinative bonds on one side and hydrogen bonds on the other. Surprisingly, when the crystals were manually ground for 5 min before irradiation, the conversion to dimer 1.2 remarkably increased to 88% in only 4 h of UV irradiation time. Overall, the role of manual grinding was not only to increase the

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

• cell parameters and reflection intensities for compound 7b (a three-dimensional set) were measured on an Xcalibur EOS autodiffractometer (Mo Kα irradiation, graphite monochromator, 150 K). Orange monoclinic crystals, chemical formula C21H14NO2Cl3, М = 418.68, a = 11.4480(3), b = 7.4883(2), с = 21.7720

• added and incubated for another 2 h under CO2 incubator conditions. At the end of cultivation, the medium with MTT was completely removed from the wells, and the formed formazan crystals were dissolved in DMSO and the optical density of the resulting solution was measured at 540 nm. The level of