α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• with the addition of 0.1% formic acid. The use of other eluents such as acetonitrile and different ratios of hexane/ethyl acetate, dichloromethane/methanol as well as the application of methods for the isolation of triphenylphosphine oxide by complexation with calcium and magnesium salts [54][55] or

Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis

• Lihua Wei,
• Rui Yang,
• Zhifeng Shi and
• Zhiqiang Ma

Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151

• favored complexation, while the phenyl substitution at C4 promoted a stable coordination-bond formation. Alternatively, (S)-130 could be furnished using Cu complex 129 in the desymmetrization step with comparable efficiency (98% yield and 91% ee), and was likewise transformed into 131 in four steps

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• –guest complexation realizes a reversible ON-OFF-ON type pseudo-monomeric ligand-gated ion transport switch [91]. The development of these pillararene-based materials has enriched the dynamic regulation methods of supramolecular structures and provided innovative approaches for prodrug design. 2 Stimulus

• ]arene (WP7) by adding 14 anionic carboxylic acid groups to both sides [102]. They explored the pH-dependent complexation of WP7 with paraquat derivative G1 in water. The host WP7 and guest G1 form a 1:1 pseudorotaxane, with an association constant of (2.96 ± 0.31) × 105 M−1. Furthermore, they leveraged

• complexation between SC4A and myristoylcholine is stabilized by the electrostatic interaction between the negatively charged sulfonate groups and the positively charged quaternary ammonium groups. The interaction between the host and guest reduces the critical aggregation concentration (CAC) to form binary

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

• these complexes, the cation coordinates with the fluorine atoms, while the anion interacts with the positively charged hydrogen atoms. The complexation is thermodynamically favorable when compared to the isolated species (ions and 1.2.3-c.c.), as indicated by the ΔH0 of formation: −32.5 kcal mol−1 for

• , such as stacking, electrostatic hydrogen bonding, and complexation with ions. The interplay of steric effects, dipolar repulsion, and electron delocalization emerged as critical factors in governing the stability of isomeric fluorinated cyclopropanes. These findings not only deepen the understanding of

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• the formation of a borate complex [61]. Diarylborinic acids have also been exploited for stereoselective 1,1'-glycosylations through the formation of a 1-O-monoborinate ester, resulting from the complexation of a 1,2-dihydroxyglycosyl acceptor with a diarylborinic acid derivative. Concurrent

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

• energies computed at 298.17 K. We also extended this study to the interaction between complexes 15a–d and benzene (14) and computed the corresponding complexation energies as In addition, Figure 4 includes the chief geometric parameters of the different complexes, as well as the corresponding free energy

General method for the synthesis of enaminones via photocatalysis

• Paula Pérez-Ramos,
• Raquel G. Soengas and
• Humberto Rodríguez-Solla

Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116

• mechanism for this reaction is proposed in Scheme 5. A ternary complex is initially formed upon complexation of 3-bromochromone (7a) with NiBr2-dmbpy. By virtue of being coordinated to a Ni-center, the β-carbon is activated toward nucleophilic attack of the amine, furnishing 2-amino-3-bromochromenone I

• photocatalytic protocol for the direct formation of enaminones from 3-bromochromones is reported. The process involves a Ni(II)-catalyzed hydroamination, followed by photocatalytic reductive debromination. Mechanistic studies suggest that the key step of this transformation is the complexation of the starting 3

Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer

• Hao-Sen Wang,
• Lin Li,
• Xin Chen,
• Jian-Li Wu,
• Kai Sun,
• Xiao-Lan Chen,
• Ling-Bo Qu and
• Bing Yu

Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100

• pathway initiates with ground-state complexation 90 between HRP-12 and HFIP via hydrogen bonding. Following visible-light excitation of 90, intersystem crossing (ISC) from the S1(LE) to T2 state generates the catalytically competent triplet excited state 91. This N-centered radical species subsequently

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

• epoxides 23b and 23a with the non-protected variant 23c, and reacting it with sulfone 27 after pre-complexation with Ti(OiPr)4, again led only to decomposition. Given the unsatisfying results, Uguen and co-workers replaced the epoxides 23a–c to monoethers 46a and 46b, derived from trans-2,3-epoxy-1,4

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

• and I. Without any metal coordination, DFT suggests conformer I is more stable than conformer II by ≈60 kJ/mol. However, upon complexation with Li+, both complexes 2 and 3 are remarkably similar in energy with the difference of less than 1 kJ/mol. This very small energy difference should be too small

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

• obtained using either 1:1 or 1:2 binding models. This is likely due to their intermediate size of chain lengths, which are neither long enough for 1:1 binding nor capable of squeezing a dimer for 1:2 complexation. Notably, the unsubstituted ultracycle B4 [31] without the pendant OH groups on the lower rim

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

• by adding carbonate (in the form of 18-crown-6 complexed Cs2CO3) showing slow-exchange of NMR signals (DMSO-d6, [1] = [salts] = 1 mM, 400 MHz, 298 K). (c) Fitted binding curve of carbonate complexation with receptor L as derived from NMR titration. (a) Single crystal structure of complexed Cs3PO4

Chitosan-supported CuI-catalyzed cascade reaction of 2-halobenzoic acids and amidines for the synthesis of quinazolinones

• Xuhong Zhao,
• Weishuang Li,
• Mengli Yang,
• Bojie Li,
• Yaoyao Zhang,
• Lizhen Huang and
• Lei Zhu

Beilstein J. Org. Chem. 2025, 21, 839–844, doi:10.3762/bjoc.21.67

• , which acts as a base. Subsequently, I undergoes oxidative addition and complexation with the amidine 2 to generate intermediate II. This intermediate then undergoes reductive elimination to form intermediate III, releasing CS@CuI back into the system. Finally, the coupling reaction between the carboxyl

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

• provides (together with the similarly exothermic complexation of calcium complex 7 with hydrazone) driving force for the catalytic cycle, but, on the other hand, may impede enantioselectivity, because of a "backwater" effect equaling out outcomes from different reaction pathways before intermediates are

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

• spectroscopic characterization of C1 along with determination of its inherent aqueous solubility and self-association properties. Next, we present the X-ray crystal structure of C1 as its C1·Me6CHDA complex. Subsequently, we describe a qualitative investigation of C1·guest and M1·guest complexation by 1H NMR

• spectroscopy and quantitative investigation by isothermal titration calorimetry (ITC). Finally, we discuss the trends in binding affinity observed for C1·guest and M1·guest complexation. Design, synthesis and characterization of C1 In order to disentangle the effects of the ionic group (sulfonate versus

• ). Qualitative study of C1·guest recognition properties by 1H NMR spectroscopy Next, we decided to perform a qualitative investigation of the host–guest properties of C1 by 1H NMR spectroscopy. Figure 3 shows the chemical structures of a panel of guests that were studied and the complexation-induced changes in

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

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• Reichardt's dye [53][54][55] as an indicator. These experiments measure the blue shift of Reichardt's dye upon complexation with an HB donor (Figure 3A, and Figures S13–S18 in Supporting Information File 1), from which the dissociation constant (Kd) of the HB complex can be determined. A smaller Kd value

• technique can be employed as a general approach for quantifying the energetics of HB interaction-enabled binding processes. Additionally, the free energies of HB complexation calculated at the PCM(MeCN)-M06-2X/6-31+G(d,p) level correlate well with our experimental data, allowing for binding affinity

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• ., metal coordination interactions and hydrogen bonding), providing access to various multiresponsive orthogonal self-assemblies or smart supramolecular polymers [24][25]. For example, the discovery of cucurbit[8]uril complexation in a 1:2 and 2:2 host–guest stoichiometry leads to a wide spectrum of

• between hydrogen atoms of G1 and the nearby phenyl groups of H2, with a distance of 2.7–2.9 Å (Figure 3a and Figure 3b). These results provided conclusive evidence for the 2:2 recognition mode through interaction of two guests with two macrocycles. With the 2:2 host–guest complexation pattern in mind, a

• coordinating metal ions. In such supramolecular polymers, orthogonal host–guest and coordination interactions are responsible for polymerization. Host–guest complexation and zinc coordination When forming supramolecular polymers, an AB-type monomer, i.e., the guest G2, is supposed to interact with the

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• dual activity as a metal catalyst as well as a Lewis acid [8][9][10][11]. However, in many cases, the role of copper is not clear and both activities often work synergistically. In all other cases, copper’s activity is due to the coordination/complexation with unsaturated systems, but it is rarely

• to multiple C–C bonds generates extended carbon radicals capable of giving further functionalization. Regarding the ionic mechanism, the key step generally comprises the complexation with the unsaturated substrate leading to activation of the alkenyl/alkynyl moiety towards a nucleophilic attack. In

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• ready receptor preparation by metal complexation. The reason for the underrepresentation is the competitive nature and excellent ligand properties of oxalate which not only is associated with the aforementioned diseases but also poses a serious hazard for metal-driven self-assemblies because the dianion

• conjugated base of the smallest dicarboxylic acid, stands out from the list of highly relevant analytes because oxalic acid is found in common edible plants and its corresponding dianion is tied to several diseases, e.g., the formation of kidney stones through complexation of calcium and precipitation of

• acetate salt results in a charge-neutral and bench-stable [L2Zn2] metallocontainer. Purification of the complex is achieved by lyophilization which accomplishes the removal of acetic acid as only byproduct of the complexation reaction and DMSO as solvent. The charge-neutral receptor is obtained as a

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• square nanobrackets, is designed, synthesized and applied to single-walled carbon nanotubes (SWNTs) for their diameter-based separation. The complexation between copper ions and dipyrrin moieties of the nanobracket gives Cu-tethered square nanobrackets, which is confirmed by absorption, Raman and MALDI

• diameter range. The diameter selectivity is supported by the theoretical calculations with the GFN2-xTB method, indicating that the most preferred SWNT diameter for the square Cu-nanobrackets is 1.04 nm. Keywords: complexation; diameter; extraction; interlock; nanobracket; single-walled carbon nanotubes

• complexation between host molecules and SWNTs are strongly related to the molecular structures, making it possible to tune the binding affinity [8]. The host molecules we employed so far for CNT separation through molecular recognition have been developed as “nanotweezers” [9], “nanocalipers” [10] and

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• this conjecture, the present reaction is proposed to involve reversible complexation between the alkyne and the cationic iodine(III) electrophile and subsequent trans-addition of the azole nucleophile, the latter step being coupled with concomitant deprotonation of the N–H bond by the triflate anion

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• either 1) covalent functionalization of the fullerene surface with polar moieties or 2) complexation with water-soluble host molecules or polymers. Related to the former approach, the Nakamura group [11], Wudl group [12], and Hirsch group [13] reported initial work in the early 1990s on water-soluble C60

• solubility [14][15]. As early examples of the latter approach in the 1990s, Wennerström and co-workers reported the study of supramolecular BiCAP complexation of C60 with γ-cyclodextrin (γ-CD) [16]. Shinkai and co-workers synthesized water-soluble calixarene derivatives to form water-soluble complexes with

• C60 [17][18]. By either chemical functionalization or complexation of the fullerene core, a number of biocompatible fullerene materials with interesting biological activities were recently prepared and reported [19][20][21][22][23][24]. We have reported water-soluble complexes of C60 with a nontoxic

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• -workers introduced a switchable system based on a terpyridine (terpy) ligand (Figure 8), which is structurally similar to the diphenylpyridine units used by Zimmerman in rigid clips, but can change their conformation upon complexation by a metal cation [32][33]. When substituted at the 6 and 6" positions

• host–guest complexation, it can also only bind to coordinating guests (terpyridine, bipyridine) due to the proximity of the coordination sphere with the binding pocket. Tweezers 11 with NDI arms and an extended pyridine-hydrazone-pyridine-hydrazone-pyridine switchable unit have thus been developed

• coordination-switchable tweezers for switching between two magnetic states that are stable at room temperature [44]. To increase the magnetic coupling between the metal center the group investigated the Mn(III)–salphen tweezers 14 that can coordinate in apical position to cyanide ions. The complexation of CN

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• applying high pressure (6 GPa) in the complexation between [9]CPP and C60 [42]. In these examples, partial charge transfer (CT) from the CPP host to the guest was observed, but the degree of CT was limited. Furthermore, no clear effects of CT on the physical properties have been reported. We have already

• 1H NMR titration experiments (see Supporting Information File 1, Figure S1), indicating that the complexation was exergonic with a ΔG = −19 kJ mol−1. This value is about 20 times higher than that of the neutral complex, [10]CPP⊃[5]CPP (Ka = 0.053 × 103 L·mol−1 in TCE-d2 at 50 °C, ΔG = −11 kJ mol−1

• ) [31]. The increased Ka is most likely attributed to the ionic interaction caused by the presence of the cationic species, as will be discussed below. To clarify the effect of the polar interaction, the host–guest complexation was studied in a polar solvent, such as nitrobenzene and acetonitrile