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

• stripping from activated carbon using α-cyclodextrin. J. Am. Chem. Soc. 2021, 143, 1984–1992. Copyright 2020 American Chemical Society. This content is not subject to CC BY 4.0. Solid-state structure of the complex 2β-CD·HAuBr4·DBC. (a) Capped-stick and space-filling representation of different views of 2β

A versatile route towards 6-arylpipecolic acids

• Erich Gebel,
• Cornelia Göcke,
• Carolin Gruner and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88

• . It contains a six-membered ring and is, like its five-membered correlate, known for its secondary structure inducing properties, which are particularly useful in the design of peptide conformations. We present a new and improved way to generate enantiomerically pure pipecolic acid derivatives with

• structure of pipecolic acid is rather challenging and often necessitates early-stage derivatization followed by the formation of the six-membered ring [29][30][31][32]. An alternative is to utilise derivatization reactions such as Suzuki–Miyaura [33] or Sonogashira–Hagihara [34] cross-coupling reactions on

• the Sonogashira–Hagihara cross-coupling products [35]. Furthermore, an in-depth NMR analysis was conducted on the resulting constraints leading to conformational structure predictions. ᴅ-2-Aminoadipic acid (1) [36], a side product formed in the pharmaceutical semisynthesis of 7-aminocephalosporanic

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

• pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen–lithium–oxygen bond angle is approximately 98.83

• durability, low harmful, and convenient alternative to heavy-metal reagents [10][11]. Hypervalent iodine compounds exist as trivalent (λ3-iodanes) or pentavalent (λ5-iodanes) species. The λ3-iodanes have an T-shaped structure [12], with the energetically preferred arrangement of the two most electronegative

• projecting outward denoted by an asterisk. Furthermore, the resulting crystal structure reveals that 1 is also a distorted planar macrocyclic system consisting of the amino acids carbonyl oxygens facing inside the ring. All three benzyl groups are located above a single plane (more figures are provided in

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• ; the first one involves the direct carbonization (at 200–400 °C) of the precursor material for 24–100 hours under solvent-free conditions. The obtained carbon nanomaterials exhibit predominantly a graphitic core structure. In contrast, under hydrothermal conditions, the starting substrates were

• dissolved or suspended in water, and the resulting mixture transferred to an autoclave and treated at a temperature ranging 140–200 °C; the treatment yields CDs with an amorphous structure. The synthetic procedure, as well as the structural and morphological characteristics of these materials, have been

• previously reported by the research group of M. Selva and A. Perosa (see also Supporting Information File 1 for further details) [30][31][32][33][34][35]. As shown in Table 1, the materials synthesized via pyrolysis exhibit a graphitic core, characterized by an ordered structure, whereas those synthesized

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• , lycopodine features a characteristic tetracyclic structure with a bridged cyclohexanone. To address the challenges associated with constructing the complex ring systems of this structure, She and co-workers devised an intramolecular aza-Prins cyclization strategy to form both the bridge ring and the N-hetero

• [2,1-a]isoquinolin-3(2H)-one framework is a pivotal core structure among various pyrrolo[2,1-a]isoquinoline alkaloids, exemplified by (+)-crispine, annosqualine, and erysotramidine, among others (Scheme 5) [29]. These bioactive alkaloids exhibit a broad spectrum of biological activities, including

• notable example is (−)-cephalocyclidin A, a cytotoxic pentacyclic cephalotaxus alkaloid [33][34]. Although the molecular structure contains a benzo-bridge ring system, disconnection of this bridge reveals a critical tricyclic N-heterocycle. To efficiently synthesize this tricycle, polycyclization of

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• mechanisms and reasons behind the fluorescence color and the fluorescence quantum yield and derive structure–optical property relationships. We will provide the reader with an overview of the perspectives and challenges of open-shell light-emitting radicals and discuss what to do to solve the remaining

• in Py2MTM is increased 3000-fold. The nuclear spin of the nitrogen in PyBTM and Py2MTM can couple with the radical electron spin, leading to EPR spectra with hyperfine structure [58]. Effectively, the substitution in ortho-position has strong electronic as well as steric effects, allowing to tune the

• extension of the Cz donor structure to benzocarbazole (BCz) and dibenzocarbazole (DbCz) follows the trend of the above described three-state model (see Figure 11). However, further extension to aza[7]helicenes also leads to contradiction with the model (cf. compounds 35 and 36 in Figure 8a and b). The ϕs of

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• , further investigation is needed to prove this observation. However, the mentioned alkaloids have high potential as medications. Based on the above, research on the total synthesis of these alkaloids and their closely related derivatives is crucial for further confirming their structure and for ensuring

• publications [19][23][24] confirmed the structure with IR and MS data, or by reactivity. Herein, we report the full set of assigned 1H and 13C NMR data for both the base and the dihydrochloride salt. In the course of our efforts devoted to elaborating a new and efficient synthesis of brevicarine (2), we

• catalyst, overreduced product 31, i.e., the tetrahydro derivative of racemic brevicolline ((±)-1) was obtained in 91% yield. Structure determination of 31 was supported by single-crystal X-ray diffraction, as well (Figure 2). Changing the catalyst [Pd(OH)2, Ru, Rh], did not alter the course of the reaction

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• examples of amino-sulfonoxylations using tethered nitreniums. Putative reaction mechanism. (A) Scale-up and (B) applications. Optimization results. Structure–reactivity relationship with nitrenium tethers. Examination of sulfonic acid scope. Substrate scope exploration with an emphasis on stereocontrol and

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• of D–A structures makes them the ideal structures to further understand the structure–property relationship of D–A molecules for optimizing their photocatalytic performance by simpler modification of the different D–A subunits. In particular, D–A structures featuring sulfur-based acceptors and

• is a particular interest in the obtainment of organic molecules with well-balanced redox potentials in the excited state that can act as bimodal photocatalysts, facilitating their use in oxidative and reductive quenching cycles. In this sense, it is crucial to understand the molecule's structure

• –properties dependence to modulate its optical and photoredox properties [4]. For instance, molecules with donor–acceptor (D–A) structures, classically used as OLED emitters, have gained relevance by finding alternative applications in the field of photocatalysis [5]. In this type of structure, the electron

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

• Zhiyang Zhang,
• Jialei Hu,
• Hanfeng Ding,
• Li Zhang and
• Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

• their total synthesis. Two synthetic studies were disclosed successively by Sarpong [27] and Jirgensons [28], both focusing on the construction of the unique methanoindene cage structure (A1A2B ring system). Building upon our previous syntheses of phragmalin-type limonoids [29], we herein disclose a

• 11 in the presence of AcOH by exposure to UV-light at 254 nm occurred exclusively to provide an inseparable mixture of 32 and 33 (Table 1, entry 5). Subsequent dehydration of the resultant mixture with SOCl2 and pyridine yielded separable enones 34 (51%) and 10 (9%) over two steps. The structure of

• ). Construction of α-iodoenone 13. Construction of aldehyde 14. Synthesis of the advanced intermediate 10 (in the X ray structure of 10 solvent molecule is omitted for clarity). Optimization of the interrupted Nazarov cyclization.a Supporting Information Deposition number 2406738 contains the supplementary

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• trifluoromethyl and nitro groups. Furthermore, substrates 15m–o derived from aliphatic amines, also performed well, furnishing pyrazolodiazepines 16m–o in up to 89% yield. The structure of 16m, a representative compound of this series, was confirmed through single-crystal X-ray diffraction (scXRD) analysis

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

• protoberberine and protonitidine alkaloids are characterized by an isoquinoline ring skeleton. An analysis of their molecular structures revealed that the two alkaloids share a basic structure, differing only in the junction of the B-ring. In 2021, Liu and Jiang designed new pyridyne precursors, which underwent

• discussion emphasizes structure–reactivity relationships and catalytic design principles that enable predictable access to distinct molecular architectures from shared synthetic intermediates. This review serves as a conceptualized platform for controllable/divergent synthesis, arousing more state-of-the-art

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

• binding sites to enhance anion binding [30]. The recognition capabilities of these ultracycles toward a range of dicarboxylates were successfully demonstrated. Results and Discussion Synthesis and structure The ultracycles B4aH, B5aH, and B6aH were synthesized following the previously reported procedure

• hydrogen bonding and anion–π interactions between the host and guest, we carried out geometry optimizations using M06-2X at the 6-31G(d) level of theory, taking the [B4aH·C72−] complex as a representative example [35][36]. The optimized structure, shown in Figure 3, reveals a 1:1 complex in which the

• interactions, the host undergoes conformational adjustments: the distance between the two submacrocycles increases, and the glycol chains adopt extended conformations compared to the structure shown in Figure 1. These results suggest that the experimentally observed strong binding capability and selectivity of

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

• organoboron compound with CuOt-Bu and subsequent SN2’-selective allylic alkylation of 1. The densely functionalized structure of these dimerization products offers a versatile synthetic handle for further chemoselective functionalization. Considering the presence of two enolizable esters together with the

• of the twofold utility of KOt-Bu, we explored the formation of this new cyclopropane structure directly from gem-dichloride 5. By using this base under standard conditions, product 20 was selectively obtained in similar yield, albeit with diminished diastereoselectivity (Scheme 5b). Conclusion In

Data accessibility in the chemical sciences: an analysis of recent practice in organic chemistry journals

• Sally Bloodworth,
• Cerys Willoughby and
• Simon J. Coles

Beilstein J. Org. Chem. 2025, 21, 864–876, doi:10.3762/bjoc.21.70

• data guidance. We suggest first steps that researchers can take to move towards a positive culture of data sharing in organic chemistry. Routine actions that we encourage as standard practice include deposition of raw and metadata to open repositories, and inclusion of machine-readable structure

• from the ‘all data’ group which combines the other categories, because an excellent data culture is already established for crystallographic data publishing. All journals expect CIF validation using accessible tools (checkCIF [34] or enCIFer [35]), and deposition of CIF files and structure factor

• tables with the Cambridge Crystallographic Data Centre (CCDC), enabling full access to the contained structure information via the CSD repository. For other data types, 11 of the 12 journal titles recommend that primary data are deposited in a repository and encourage authors to consider FAIR data

Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• + 2] cycloaddition established, the scope and pivotal properties of the core structure was assessed (Scheme 1). Single point modifications of the tethered backbone were tolerated, enabling access to small 3D bicyclic scaffolds 4b, 4c, and 4d containing both a boron and ester handle. Consciously aware

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

• -pairing) could be enhanced along with the charge of the anion and its binding affinity with L (from Cl– to CO32–, and PO43–). Notably, for the first time, direct ion-pairing between receptor-complexed phosphate and 18-crown-6 complexed cesium was observed in the single crystal structure, facilitating

• interaction in nonpolar solvent could be stronger than that in polar solvent [45][46][47][48]. The ion-dipole interaction between complexed Cs+ cation and receptor–sulfate complex was first identified by single crystal structure analysis (Figure 2). The overall stoichiometry of L, 18-crown-6, Cs+, and SO42

• − was 4:5:4:2 in the crystalized structure. Like the structure of K2SO4 complexes [31], one Cs+ cation is encapsulated by 18-crown-6 and further stabilized by one ion-dipole interaction with the O=C unit of the hexaurea receptor. The Cs···O distance is measured at 3.2 Å. The other two Cs+ cations are

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• -art technologies ranging from energy-storage materials [6][7] to pharmacology [8][9][10][11], materials chemistry [12][13], control of peptides structure [14][15] or proteins [16], as antibacterial agents [17][18], smart coating [19], or multivalent photoresponsive systems [20][21], to name only a few

• predicted using quantum chemistry to describe the Z→E isomerization in azobenzenes, namely: rotation, inversion, inversion-assisted rotation, and concerted inversion depending on the structure of the azobenzene [40][41][42][43][44]. For PAPs, Calbo et al. showed by DFT calculations that the inversion

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• spectroscopy, the structure of 4-(1-methylamino)ethylidene-1,5-diphenylpyrrolidine-2,3-dione (5a) was also verified through single-crystal X-ray diffraction. Furthermore, the synthesized molecules were evaluated for compliance with established drug-likeness rules (Lipinski, Veber, Ghose, Egan, and Muegge), as

• -pyrroline-2-ones 1a–e and 4-methoxybenzylamine (2) in absolute ethanol yielded 4-[1-(4-methoxybenzyl)amino]ethylidene-1,5-disubstituted pyrrolidine-2,3-diones 3a–e (Scheme 1) [19][20][21]. In addition to nuclear magnetic resonance spectroscopy (1D, 2D NMR), the structure of 3a has also been proven via

• -hybridized carbon atom directly bonded to the nitrogen atom of the secondary amino group of compound 5a. In the structure of each pyrrolidine-2,3-dione derivative 3a–e, there is an α,β-unsaturated ketone moiety in which the π systems of the C=C and C=O bonds could overlap each other to yield an extended

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• Bansal and co-workers [44] revealed the potential formation of aza-QC derivatives at low temperatures. However, isolation of these derivatives proved difficult, as rapid rearrangement to azepine analogues occurred at temperatures exceeding 0 °C. On the basis of the quadricyclane or azepine structure

• described a variety of potential rearrangements for oxa-NBD and oxa-QC derivatives [32][34][36][37]. Therefore, in-depth 2D NMR analysis combined with mass spectrometry was attempted to elucidate the structure of O-UnS2. Notably, an additional singlet proton signal (integrated as 1 proton) corresponding to

• the unidentified species was observed, which cannot be present in the structure of O-QC2. Further irradiation over 18 hours resulted in additional rearrangements or photodecomposition, which were not analyzed further. At slightly lower concentrations (5.0 mg substance in 650 μL CDCl3) quantitative

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• exhibited higher stability compared to 4d and 5d transition metals. Through the study of a series of previous experiments, it was shown that the electron density of the nitrogen atom in the quinoline structure significantly affects the efficiency of nickel-electrocatalysis; however, other N,N- or N,O

• and the overall structure of the complex highly influence the oxidation potential of Pd(II). At first, a complex of phenylpyridine with palladium (including insertion of Pd to C–H bond) and dialkyl phosphonate was formed, followed by anodic oxidation to give the final coupling product. In 2023, Zhou

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

• sphere. The phosphate ligands are in cis-position with respect to each other. The structure of 4 shows similarities to that of a BINOL-derived calcium phosphate complex that also crystallizes with four methanol ligands, creating an octahedral coordination sphere with phosphate ligands in cis-position [52

• ]. As observed earlier [53], cis/trans preferences in octahedral calcium complexes are influenced by small changes in sterics. Further details on the structure of 4 can be found in Supporting Information File 1. Complex 4 appeared to be a well-defined achiral model system for the catalyst combination

• later stages of the catalytic cycle, are less likely to racemize without bond breaking. The barrier to pyramidal inversion has been found to be 15.1 kcal·mol−1. Berry rotation itself proceeds via a tetragonal pyramid as transition-state structure and does therefore not occur here. A second isocyanide

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• periphery of the FimH form the basis of the higher FimH affinity of the E isomers (as was argued in similar case [15]) (cf. Supporting Information File 1, Figure S25 and Figure S26). A possible allosteric regulation of the CRD structure [55][56], on the other hand, which might be effected by one of the

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• fluorophore derivatives bind the Pepper aptamer with affinities in the low nanomolar range [12]. Crystal structure analyses revealed that in the ligand binding pocket, a characteristic hydrogen bond is formed between the hydroxy group of the N-hydroxyethyl substituent of HBC and the N7 of G41 [12][13]. We

• . HPLC traces were recorded with UV absorption by 260 nm. Structure-guided approach for engineering the (non-covalent) fluorescent light-up aptamer Pepper into its covalent counterpart [11]. a) Secondary structure of the Pepper aptamer [12]; b) chemical structure of the fluorophore HBC530 [7]; c) three

• -dimensional structure of the Pepper binding site with a bound HBC derivative (pdb code 7EOM). The hydrogen bond between N7 of guanine in position 41 (G41) and the hydroxy group of HBC is highlighted as gray dashed line [12]; d) concept for covalent attachment of HBC fluorophores to the N7 atom of G41 of the

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

• alkyl sulfate ionic groups. The X-ray crystal structure of the C1·Me6CHDA complex is reported. Host C1 is significantly less soluble in water (4 mM) compared to the analogous acyclic CB[n] host M1 which features sulfonate ionic groups (346 mM). Host C1 does not undergo significant self-association

• are acyclic CB[n]-type receptors which have been extensively studied by our lab and others over the past decade [42][43][44][45][46][47][48][49][50][51][52]. Figure 1 shows the chemical structure of the prototypical acyclic CB[n]-type known as M1 [53][54]. M1 features a central glycoluril tetramer

• acyclic CB[n] are not macrocycles, they are preorganized into a C-shaped geometry by virtue of their polycyclic chemical structure and display binding affinities approaching those of macrocyclic CB[n]. M1 and analogues display outstanding biocompatibility and have been used for a number of in vivo