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Search for "cation" in Full Text gives 739 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Thermodynamics and polarity-driven properties of fluorinated cyclopropanes
Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137
- 1.2.3-c.c., it is capable of interacting with ions and potentially acting as both an anion and a cation carrier. To evaluate this property, Na+ and Cl− ions were simulated in interaction with one and two molecules of 1.2.3-c.c., forming complexes akin to a "sandwich," as illustrated in Figure 3. In
- 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
Influence of the cation in hypophosphite-mediated catalyst-free reductive amination
Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130
- hypophosphorous acid are commercially available in bulk amounts, however, their usage is understudied in organic processes. While NaH2PO2 has proved to be an efficient four-electron reductant in the catalyst-free reductive amination, the influence of cation in hypophosphite salt has not been studied yet. This
- investigation of cation influence on the efficiency of reductive amination, a commercially available NaH2PO2, and in situ synthesized LiH2PO2, NaH2PO2, KH2PO2, RbH2PO2, and CsH2PO2 were compared. To account for the reactivity of H3PO2 as is, the reaction outcome both for the neutral XH2PO2 (where X is Li, Na, K
- has shown clear influence of the cation in the hypophosphite salt on the effectiveness of the reductive amination. The acidity of the reaction media was a key factor affecting the equilibrium in the interaction between carbonyl compounds and amines. Intermediately acidic media is the optimal for the
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
Beilstein J. Org. Chem. 2025, 21, 1627–1638, doi:10.3762/bjoc.21.126
- 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
- efficiency of crown ethers as components in cation-selective fluorescent probes has been extensively explored [7][30], to the best of our knowledge no previous computational DFT studies on the selectivity of crown ethers of different sizes with Ba2+ have been reported. Therefore, we explored (Scheme 2A) the
- binding between this cation and 12-crown-4 (16a, n = 1), 15-crown-5 (16b, n = 2), 18-crown-6 (16c, n = 3) and 21-crown-7 (16d, n = 4), to form Ba2+·crown ethers 15a–d. We compared the corresponding binding energies by means of the following isodesmic equation: Where the different terms correspond to Gibbs
Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads
Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121
- anion of the Pe moiety. Additionally, a shoulder signal observed near 500 nm was attributed to the radical cation of the PTZ(TPA) unit. However, although previous studies selectively excited the Pe moiety and attributed the 725 nm band to the LE state of Pe moiety, such an assignment may not be directly
- attributable to the Pe radical anion and the PTZ(TPA) radical cation appeared at ≈600 and ≈500 nm, respectively (Figure 7). The electron transfer time constant was determined to be 7.6 ps, significantly slower than that of Pe–PTZ(TPA)2 (120 fs or faster), reflecting the effect of the phenyl spacer that
General method for the synthesis of enaminones via photocatalysis
Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116
- oxidative state PC1* that interacts with morpholine (8a) to generate the corresponding aminium radical cation. To gain a better understanding of the process, the formation of the enaminone product 9a was monitored overtime by 1H NMR, which confirmed that the the reaction was complete within 2 h. Furthermore
- . Simultaneously, acridinium photocatalyst PC1 absorbed energy and transitioned from the ground state to excited state under visible-light irradiation. This excited state PC1* is quenched by the amine, generating the amine radical cation and PC1 radical via a single-electron transfer (SET) process. Then, the C−Br
Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones
Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113
- terminal S‒CH2 position, leading to the formation of the sulfonium cation 11 and the delocalized heterocyclic anion 12 (Scheme 6). In the next step, competitive addition of both intermediate species yields either thioaminals 9 or dithioacetals 10. However, a slow isomerization of the thermodynamically less
Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides
Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110
- conditions is due to a favorable formation of EWG-substituted aryl radicals from the iodonium cation, based on their reduction potentials and bond-dissociation energies calculated by Romanczyk and Kurek [45]. The reduction potential in SET reactions for iodonium salts with EWG-substituted aryls significantly
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- electronic behaviors reminiscent of nitrogen-doped azulenes, featuring strong absorption dissymmetry factors (|gabs|) at 345 nm – 1.2 × 10−2 for compound 20a, 1.0 × 10−2 for 20d, and 1.3 × 10−2 for 20e (Table 5). Notably, the radical cation form of compound 20e (20e•+) exhibits pronounced CD signals
- BCPL value of 13.2 M−1 cm−1. Notably, compound 21c undergoes reversible redox interconversion to its radical cation 21c•+ and dicationic 21c2+ states via chemical oxidation, enabling controllable switching between antiaromatic and aromatic configurations. These results provide a compelling strategy for
- | 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
Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds
Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105
- the diazonium salts are made alkaline the para-fluorine atom is so readily replaced by a hydroxy group, and that the 4-hydroxy-2,3,5,6-tetrafluorobenzene cation is the entity formed first [90][91]. A 50 mL round-bottomed flask equipped with a mini magnet was charged with pentafluoroaniline (0.64 g
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- a preparation of oxetanes via silicon-directed electrophilic cyclisation of homoallylic alcohols 49 (Scheme 12) [46]. The reaction was promoted by a bromonium cation and moderate to high yields of oxetanes 50 were obtained. The authors claim the reaction was diastereospecific for disubstituted
Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer
Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100
- the concurrent generation of the carbon cation 55. This cation was subsequently trapped by a nucleophile, leading to the formation of product 54. This system demonstrated a broad applicability for the general nucleophilic amination of benzylic C–H bonds. The substrate's scope and selectivity were
- it into the byproduct 46 and generating a carbon-centered radical 62. Species 62 is trapped by heteroarene 60, leading to the formation of the intermediate 63. This intermediate 63 undergoes SET and proton transfer with the assistance of O-anion 64 and the Br-5CzBN+• radical cation, delivering the
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- by a naphthalene-to-azulene rearrangement. The alternative radical cation mechanism has a higher energy barrier than the arenium cation-mediated reaction. Notably, only one of the pentagon–heptagon pairs exhibits an azulene-like electronic structure and aromaticity, as confirmed by the analysis of
- calculated NICS values. Similarly, Liu and co-workers reported the synthesis of two related nanographenes from precursor 38 (Scheme 6) [47]. Oxidation using DDQ/TfOH yielded two PAHs 39 and 40 in 34% and 22% yield, respectively. The authors postulated here formation of azulene moiety through radical cation
- ]. Notably, PAH 109 forms an air-stable radical cation after oxidation. A similar intramolecular oxidation of two adjacent azulene units was also reported with the use of FeCl3 as an oxidant [73] or in one step during Suzuki coupling between 1,8-dibromonaphthalene and borylated azulene [74]. The ease of
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
- cation B and an α-carbon radical A. The α-carbon radical A then undergoes intermolecular radical addition to the acrylamide, forming a new carbon-centered radical intermediate C, which subsequently undergoes intramolecular cyclization to yield the oxindole product 88a via homolytic aromatic substitution
Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates
Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96
- . Alternatively, 3 can be formed by hydrolysis of benzylic cation I [71]. Conclusion In summary, we have disclosed an aerobic copper(II)-mediated phosphorylation of enol acetates with H-phosphonates leading to substituted β-ketophosphonates. The suggested method is versatile and can also be applied to phosphine
Gold extraction at the molecular level using α- and β-cyclodextrins
Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89
- -precipitation yields from aqueous solutions of α-CD (20 mM) and MAuBr4 (10 mM) (M = Na/K/Rb/Cs) measured at 20 °C by UV–vis spectrophotometry. Right) Structures of the adducts present in co-precipitates with different alkali metals. Reproduced from Z. Liu et al. [40], “Cation-Dependent Gold Recovery with α
Supramolecular assembly of hypervalent iodine macrocycles and alkali metals
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
- 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
- Buckminster fullerene into long range assembled structures (Figure 1B) [20]. In this contribution, we explored the cation binding abilities of HIMs with first group alkali metals such as lithium and sodium. The phenylalanine-based HIM 1 used in this study was re-synthesized following the previously reported
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
- O atom of the carboxylate group. For instance, Coote and co-workers (2019) reported electrochemical methylation of cinnamic acid 7 using the TEMPO-Me reagent via reactive radical cation 59 to give the corresponding methyl ester 44 in moderate yield (Scheme 21A) [53]. Wang and co-workers (2019
- cinnamate (44) via an electrochemical method using TBAF as the supporting electrolyte (Scheme 56) [99]. Under these conditions, the aldehyde was oxidized to give an oxonium cation intermediate 176. Moreover, Babu and co-workers (2024) oxidized an imine, cinnamalaldehyde N-tosylhydrazone (177), by using TBHP
Recent total synthesis of natural products leveraging a strategy of enamide cyclization
Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81
- quaternary center in a single step. As depicted in Scheme 1, key enamide 1 was prepared from (R)-pulegone in 6 steps. In the presence of the weak acid H3PO4, protonation of 1 generates a stabilized iminium ion 2, which then undergoes a 6-exo-trig cyclization to deliver 4 after hydration of cation 3. Notably
Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes
Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78
- , which attacks the pendant olefin to form an aziridinium cation (Scheme 2). A sulfonate counter-anion then opens this aziridinium ring in an exo-selective, SN2 reaction. We were successful in scaling the reaction from 0.3 mmol to 11.5 mmol (38-fold increase) without any erosion in yield or selectivity
Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts
Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76
- facilitated by reduced photocatalyst (PC) and the interaction of 15 with the radical cation of DIPEA. The best result, again, was attributed to molecule 5a with 60% isolated yield (Table 5, entry 1). In contrast, molecule 5b showed the worst performance with 41% NMR yield (Table 5, entry 2). For compounds 5c
Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes
Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71
- the base metal cation. Gratifyingly, we observed that the use of LiOt-Bu led to the formation of product 2 as a single diastereomer (Table 1, entry 5). A slightly lower diastereoselectivity was observed when KOt-Bu was used, which also gave rise to 2 in diminished yield (Table 1, entry 6). The nature
- addition to a second molecule of 1. Given the negative results observed for other crotonate derivatives (Scheme 3c), coordination between the Li cation and the two chlorine atoms via proposed transition state D may be crucial not only for diastereoselective control but also for the viability of this step
- second molecule of the 4,4-dichloro-2-butenoic acid derivative. We have observed that the use of lithium as base metal cation is key to achieve excellent levels of diastereoselectivity. Our study also highlights, how the dimerization products can be selectively converted into different densely
Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation
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
- dual-host systems for selective ion separation. Keywords: anion binding; cesium extraction; dual-host strategy; ion-pair interaction; solid–liquid extraction; Introduction Ion-pair interaction, defined as the electrostatic attraction between a positively charged cation and a negatively charged anion
- separation [4][5][6][7][8]. Building on the extensive research into anion and cation receptors within the realm of supramolecular chemistry [9][10][11][12], numerous heteroditopic ion-pair receptors have been elaborately developed [13][14][15]. These receptors, consisting of binding sites for both anions and
4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches
Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65
- organic cation transporter 2 (OCT2) was examined, with OCT2 playing a pivotal role in the renal elimination of both xenobiotics and endogenous compounds. The predicted results suggest that none of the studied compounds act as OCT2 substrates. Toxicity was assessed using the Ames test, a widely accepted
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- (O)(OR)2 is derived from the compound P(OR)3, not from HP(O)(OR)2. Although the exact role of HP(O)(OR)2 remains unclear, it has been established that its presence is essential for the C–H phosphorylation. In this case, a radical cation intermediate was suggested for this conversion. Heteroaromatic
- . Some other heteroarenes were also tested, but only quinoxaline was compatible with this system under the standard conditions. A radical pathway was proposed in this reaction. At first, a thiazole radical cation was formed via anodic oxidation, followed by a reaction with phosphine oxides to give a
- reaction proceeded via anodic indole oxidation, followed by a reaction with trialkyl phosphite to give the corresponding indole phosphonate (Scheme 11). Cyclic voltammetry experiments confirmed that free indole can oxidize at the anode and generate a radical-cation intermediate. Also, no product was
Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones
Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59
- internal rotation in 11 via TS8 and reaction with TMSCN to give adduct 13 (see Figure 3). Distances and bond lengths are given in pm. Catalyst 7 is replaced in TS 11-12 by concerted electrophilic intramolecular substitution with formal trimethylsilyl cation as electrophile. Please note the surprisingly
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