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

• , vinylferrocene [30], and vinylphosphaferrocene [31]) in the AMD/KR reactions using Mo/(R)-L1. The views of the molecules from the view point opposite to the central metal cations (Mn(I) or Fe(II)) are illustrated at the bottom of Figure 2. All the three compounds possess the similar structural features: (1

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

• their 2,5-positions through sp3-hybridized meso-carbon atoms [10]. The ability of CPs to selectively bind anions [11], cations, ion pairs and neutral guest species, combined with the versatility to introduce diverse functional groups, has enabled the fabrication of calix[4]pyrrole-based supramolecular

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

• derived from propargylated and 2-azidoethylated precursors possess drastically different complexation abilities towards transition-metal cations [81][82][83][84] including the formation of unique inherently dinuclear iridium(III) complexes with cone calix[4]arenes having pairs of 2-(4-aryltriazol-1-yl

• affect the cycloaddition by, for instance, binding copper cations or counter anions, and thus their presence in the structures of calixarenes at the CuAAC step must be avoided. On the other hand, the unmodified amines may also contribute to undesired Cu(I) stabilization and complicate the CuAAC work up

• apparently not sufficient to provide any significant selectivity for the formation of homo/heterocapsules. Finally, since the triazole groups arranged at the narrow rim of the calix[4]arene macrocycle are capable of complexation with transition-metal cations, showing different complexation preferences

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• activation assisted by alkali metal counter cations Although strong bases can promote nucleophilic transformations of amides, such reactions have traditionally required harsh conditions [69][70]. Recently, however, the role of alkali metal counter cations in facilitating acyl substitution has been recognized

• coupled with cooperative alkali metal counter cations, have expanded the scope of amide C–N bond cleavage under mild conditions. In parallel, the installation of activating groups on the amide nitrogen has enabled chemoselective cleavage, opening the door to late-stage transformations of target amides

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

• intermediate luchudiene (21). One of the olefins in 21 is then reactivated by re-protonation, initiating a second cyclisation sequence that proceeds via cations 21a and 21b. Finally, a remarkable sacrificial carbocyclisation (rupture of the cyclopropane ring) at an aliphatic centre then generates cation 21c

• carbocation 23d. A triple asynchronous shift occurs, consisting of C12-alkyl (13→16), 1,3-hydride (12→13), and C-13 alkyl shift (16→12). This complex, concerted process directly converts the tertiary cation 23c into the tertiary cation 23d completely avoiding secondary cations and resulting in another 5→6

• (via cations 132c and 132d) and finally elimination to give 132e, with the full skeleton assembled. After selective oxidation of the C-16 position giving 132f, spiroacetal formation and esterification with the side-chain ketone affords spirochensilide A (131). The A-ring-seco triterpenoid holophyllane

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• reduction of activated aromatic cations (e.g., pyridinium, quinolinium, or benzopyrylium salts), offering mild and chemoselective access to partially or fully saturated heterocycles. More recent advances in single-electron transfer (SET) chemistry, particularly those mediated by photoredox catalysts or

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

• ; these equivalents can be transformed after the desired connection has taken place. For instance, nitroalkanes [1] and nitroalkenes [5][6] are regarded as equivalents of unavailable acyl anions and vinyloxenium cations, respectively. Reversed reactivity patterns also emerge due to non-uniform structures

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

• , only tertiary aliphatic substrates were examined, generating non-stabilized carbocations. While the transformations proceeded cleanly, yields were generally low and the scope was restricted to non-functionalized arylalkynes. A one-pot procedure for the in situ generation of benzylic cations from

• anion). Generation of tertiary aliphatic cations and intramolecular trapping with alkenes or alkynes is well known in the context of polyene cyclizations [155]. Building on Johnson’s earlier work (Scheme 48A) [156], Fañanás and Rodríguez developed an intramolecular cationic cyclization strategy to

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• CC BY 4.0. (a) Structure of the [2]rotaxane and (b) mechanism for K+ cations transport across lipid bilayers. Figure 6 was adapted from [51], C. Wang et al., “A Light-Operated Molecular Cable Car for Gated Ion Transport”, Angew. Chem., with permission from John Wiley and Sons. Copyright © 2021 Wiley

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

• cucurbit[n]uril (CB[n]) molecular containers [21][22]. Macrocyclic CB[n] display ultratight binding toward hydrophobic cations in water which renders them an attractive new class of sequestrants [23][24][25][26]. For example, Buschmann and Jekel demonstrated the use of CB[6] (Figure 1) for the removal of

• ][37]. Previously, we showed that the water-soluble methylene-bridged glycoluril dimer (G2M2, Figure 1)-based host displayed highest affinity and selectivity for planar aromatic cations (e.g., dyes) [38]. Most recently, we synthesized a series of water-insoluble catechol-walled acyclic cucurbit[n]uril

• found that the water-soluble naphthalene-walled glycoluril dimer G2M2 (Figure 1) – with its roughly co-planar aromatic walls – is selective for planar aromatic cations as guests [38]. In order the complement the tricyclic ring system present in the panel of dyes (Figure 2), we envisioned the use of even

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• reducing ability of copper(I), substrates can be reduced to radicals and oxidize copper(I) to copper(II) in the process. Copper(II) can oxidize other organic radicals to cations by SET or reversibly react with other radicals to form copper(III) species that can undergo fundamental organometallic steps such

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

• can arylate propargylsilanes and induce a 1,2-silyl shift to generate β-Si-stabilized allyl cations. Compared to the previously employed two-step halocyclization–cross-coupling sequence [22], this approach offers a shorter, [Pd]-free synthetic sequence to the modified styryl-containing tetrahydrofuran

Influence of the cation in hypophosphite-mediated catalyst-free reductive amination

• Natalia Lebedeva,
• Fedor Kliuev,
• Olesya Zvereva,
• Klim Biriukov,
• Evgeniya Podyacheva,
• Maria Godovikova,
• Oleg I. Afanasyev and
• Denis Chusov

Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130

• . The remedy for Parkinson’s disease, piribedil, was obtained in high yield. The plausible mechanism of the elaborated process was proposed and supported by DFT calculations. Keywords: amines; DFT; hypophosphites; reductive amination; role of cations; Introduction Sodium hypophosphite, NaH2PO2, is one

• fertilizers in agrochemistry phosphates [20]. Multiple literature reports indicate that changing the alkali metal cations can strongly affect diverse chemical processes including radical reactions [27], electrochemical processes [28], and biomass pyrolysis [29]. However, hypophosphites derived from alkali

• to fundamentally study the influence of the cations in hypophosphites on this process. In this work, the hypophosphites of Li, K, Rb, and Cs were obtained in situ, the influence of alkali metal cations on the efficiency of reductive amination was assessed and the obtained results were compared with

On the aromaticity and photophysics of 1-arylbenzo[a]imidazo[5,1,2-cd]indolizines as bicolor fluorescent molecules for barium tagging in the study of double-beta decay of ¹³⁶Xe

• Eric Iván Velazco-Cabral,
• Fernando Auria-Luna,
• Juan Molina-Canteras,
• Miguel A. Vázquez,
• Iván Rivilla and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126

• Abstract In this paper, the behavior of a bicolor fluorescent indicator for the detection of barium cations formed by double-beta decay of 136Xe is analyzed by means of computational tools. Both DFT and TDDFT permit to understand the origin of the bicolor fluorescent signal emitted by 1-arylbenzo[a]imidazo

• fluorescent moieties constitute promising candidates to detect Ba2+ cations [8][9] (Figure 2). Another essential component is an aza-crown ether of appropriate dimensions to capture the barium cation. In addition, one para-disubstituted phenyl (or aryl) group is installed to generate selective cation–π

• -311+G** (S0) and using TDDFT (S1). Hydrogen atoms have been omitted for clarity. Fully optimized geometries (B3LYP-D3BJ/6ccrow-311++G**&DefTZVPP(Ba) level of theory) of Ba2+·crown ethers 15a–d (A) and phenyl·Ba2+·crown ether complexes 17a–d (B). Barium cations are represented in dark blue. Descriptors

Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides

• Nadezhda M. Metalnikova,
• Nikita S. Antonkin,
• Tuan K. Nguyen,
• Natalia S. Soldatova,
• Alexander V. Nyuchev,
• Mikhail A. Kinzhalov and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110

• differs from the ones with electron-rich aryls with 0.36 eV gap between (4-NO2C6H4)2I+ and (4-OMeC6H4)2I+ iodonium cations. If unsymmetric iodonium cations are considered where one of the aryls is phenyl and the other is a 4-substituted phenyl the bond-dissociation energy is 4.0 kcal/mol lower in case of

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• | value of 1.6 × 10−3. In addition, both 29a and 29b demonstrate redox activity, undergoing reversible formation of radical anions, dianions, and radical cations. The radical cation 29b•+, in particular, exhibits a broad near-infrared (NIR) absorption band extending to 3000 nm, highlighting its potential

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

• trace amounts (<3%). Investigations on the role of both the halogen in KAuX4 (X = Br, Cl) [37], as well as of different alkali cations (Na, K, Rb, Cs) [40] upon the ability to form a co-precipitate in the presence of α-CD were undertaken. The possibility of using different cyclodextrins (α-CD, β-CD or γ

• cations, the geometry is different from that observed in {α-CD·[K(OH2)6]+[AuBr4]−}n, because coordination of Rb+ and Cs+ takes place both at OH groups and at the O atoms of the glucopyranosyl ring in the CD tori (Figure 2, right). This strong coordination, in cooperation with the geometrically favourable

• 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

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

• at Urbana-Champaign, Urbana, IL, 61801, United States 10.3762/bjoc.21.87 Abstract This study explores the solution- and solid-state assembly of phenylalanine-based hypervalent iodine macrocycles (HIMs) with lithium and sodium cations. The metal cation binding of HIMs was evaluated by addition of

• lithium tetrakis(pentafluorophenyl)borate ethyl etherate LiBArF20 and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate NaBArF24. The electron-rich, outwardly projected carbonyl oxygens of the HIM co-crystalize with the cations into bent supramolecular architectures. Both crystal structures show a

• macrocycle is electrophilic in nature. In addition, DFT results show the three outwardly projected carbonyl oxygens (formerly the carbonyl of benzoic acid) are negatively charged and can potentially bind or interact with metal cations. Figure 3 (right) shows the calculated electrostatic potential map with

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• the fluorosulfonyl imide to form sulfonyliminium cations Int-95. These then add to the activated phenylacetylene to construct the S–C bond, followed by intramolecular 1,5-hydrogen migration and aqueous workup to remove benzaldehyde, yielding the target sulfonylimine products. Both original

Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes

• Patricia Gómez-Roibás,
• Andrea Chaves-Pouso and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71

• different diastereoselectivity observed when other bases featuring different metal cations were used (Table 1, entry 2 vs entry 5), and the absence of any significant stereochemical influence from the copper complex (Table 1, entries 9–14). Lithium enolate C would then undergo a diastereoselective conjugate

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

• /bjoc.21.68 Abstract The dual-host strategy offers a straightforward approach to ion separation, yet the nature of cooperative interactions between receptor-complexed cations and anions remains poorly understood. In this study, we utilize 18-crown-6 as a cation receptor and a tripodal hexaurea receptor

• cations within a single molecule, have facilitated advancements in ion-pair recognition. This progress has led to the development of ion separation utilizing ion-pair receptors [16][17][18][19][20], which eliminate the need for auxiliary reagents to balance overall charges compared to the use of

• and making new receptors, thereby saving considerable time. However, the selectivity of ion separation achieved through the dual-host strategy may not match that of ion-pair receptors, possibly due to less defined interactions between the receptor-complexed anions and cations. Early studies employing

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

• zinc cations to align 1.1 through the formation of hydrogen-bonded coordination complexes. Thus, when a single crystal of the [Zn(bpe)2(H2O)4](NO3)2·8/3H2O·2/3bpe complex was exposed to UV irradiation (dark blue phosphor lamps, λ = 350 nm) for 25 h, only 46% conversion to 1.2 was observed via 1H NMR

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• catalysis has fared best using approaches such as destabilizing ground states by constrictive binding, guiding molecular collisions to reduce large entropic costs (e.g., pericyclic reactions), and broad, undirected coulombic stabilization of charged transition states [36], for example of cations by

• versions. Recent advances using hexameric resorcin[4]arene-based capsules [122][123][124] (Figure 4B and C), notably by Tiefenbacher [105][125][126][127][128][129][130][131][132][133], have demonstrated substrate-controlled selectivities that vary from the bulk phase due to the stabilization of cations in

• ) Self-assembling capsules can perform hydrophobic catalysis [116][117]. (B) Resorcin[4]arene building block. (C) Hexameric resorcin[4]arene-based capsules [122] include structural water. The cavity can stabilize cations (substrates or transition states) and perform catalysis using dual activation of a

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

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

• sensitivity of in situ obtained complexes 9 and 10 with CN− to different cations. It appeared that the addition of an equivalent amount of Hg(ClO4)2 to an acetonitrile solution selectively and completely restores the initial absorption and fluorescence spectra (Scheme 3). Thus, the obtained compounds