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

• , a mechanism known as HAD (H-bond-mediated aglycone delivery) [68]. The picoloyl protecting group at the remote C4–OH position has also been successfully employed to stabilize the anomeric configuration in 2,3,6-tri-O-benzylated TMS-glycoside acceptors [69]. This unusual stability of the anomeric

• configuration has been explained by the formation of a picolinium adduct, resulting from the trapping of the acidic by-product TMSOTf by the pyridine moiety of the picoloyl group during glycosylation [69]. The resulting intermediate, a picolinium-stabilized TMS-glycoside, exhibits high configurational stability

• involving TMS-glycoside acceptors require consistently acidic conditions, which places special demands on the acid stability of the protecting groups employed. This approach enabled the synthesis of β,α-1,1'-linked β-mannosyl-α-glucoside 62 and its 2-azido-2-deoxy-derivative 64, using the 4,6-O-benzylidene

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• (11%), dichloroethane (8%). and acetic acid (8%) (Figure 4b), which are particularly valued for their ability to dissolve both organic substrates while maintaining chemical stability under the reaction conditions. Notably, sulfuric acid plays a dual role – as catalyst and solvent – in these systems, a

• and presents significant mathematical complexity when dealing with intricate reaction systems. Long-term operation stability/stress testing: Ensuring long-term operational stability is a critical requirement for the practical implementation of continuous-flow nitration processes, particularly given

• in nitration systems where minor deviations can lead to thermal runaway or hazardous by-product accumulation. Therefore, conducting long-term operational stability testing becomes imperative following the development of optimized continuous-flow nitration processes to validate industrial viability

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

• pH 0) [19], and usage of an additional amount of base leads to stronger reductive properties. Moreover, the role of the cation could be critical for the thermal stability against disproportionation or aerobic oxidation of hypophosphite [38]; salts with larger cations are also more soluble in organic

• media. Finally, the combination of H3PO2 and KH2PO2 1:1 with the ratio of H2PO2− to amine 1:2 is optimal balance between solubility of reductant, acidity of the medium and stability of the reducing system providing the highest efficiency of the interaction. Under optimized reaction conditions, the

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• ]. Encouraged by the above results, we turned our attention to biaryl lactams [49]. However, in this case, the inherent resonance stability of the amide bond makes the ring-opening process rather challenging. To solve this problem, we envisioned that a cooperative catalytic system merging silver catalysis and

Transition-state aromaticity and its relationship with reactivity in pericyclic reactions

• Israel Fernández

Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125

• [1][2][3]. Initially introduced to account for the remarkable stability, low reactivity, and unique structural features of benzene and related aromatic hydrocarbons, the concept has undergone a significant evolution [4]. Since the introduction of the famous Hückel’s (4n + 2) rule [5], first clearly

• that the gain in (in-plane) aromaticity in the parent reaction is not translated into a gain in stability (i.e., a more aromatic transition structure does not translate into a lower-barrier process). Following the same methodology, the ASM of reactivity was applied then to understand the reasons behind

pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality

• Ryota Kimura,
• Satoshi Ichikawa and
• Akira Katsuyama

Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120

• stability of the chiral axis, amidine 1, which has identical substituents on the amidine nitrogen and thus does not generate E/Z isomers, was selected. In the chiral HPLC analysis using an acidic eluent [MeCN/H2O (containing 0.5% CF3CO2H) 20:80], the trifluoroacetate salt of amidine 1 was observed as two

• well as the C–N bond rotation the racemization rate could be controlled by the protonation of the basic amidine moiety. This result indicates the possibility of controlling the stability of the chiral axis by the basicity of the amidine, as well as the C–N bond, as mentioned above. Conclusion In

Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins

• Juliana V. Petrova,
• Varvara T. Tkachenko,
• Victor A. Tafeenko,
• Anna S. Pestretsova,
• Vadim S. Pokrovsky,
• Maxim E. Kukushkin and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118

• was employed. The substantial impact of the reaction conditions can be attributed to the stability of the dipole formed. The presence of mesomeric donor substituent (such as 4-OMe group) has been shown to render nitrile oxides more susceptible to dimerization in comparison to other dipoles [27][34

• -containing compound [38]; the stability of these compounds is contingent on the nature of the substituents bonded to the thiocarbonyl group, which reacts with nitrile oxide [41]. It has been demonstrated [7] that 1,4,2-oxathiazoles derived from thiourea are among the least stable compounds, gradually

Azobenzene protonation as a tool for temperature sensing

• Antti Siiskonen,
• Sami Vesamäki and
• Arri Priimagi

Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115

• they all typically result in significant changes in the absorption spectrum and/or alter the stability of the metastable isomer. In sensing, azobenzenes have been utilized, e.g., through changes in isomerization kinetics [17][18] or colorimetric properties. The colorimetric sensors are effective for

• different azo compounds [23][24][25]. More recent work has harnessed protonation to enable red-light switching [12][13][26] and to control the stability of the cis-isomer [27][28][29]. These studies have focused on how protonation affects isomerization, with less attention given on how external stimuli

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

• thiocarbonyl S-methanides 1a and 1b, respectively, in situ generated at 45 °C in absence of any trapping reagent, were described in earlier publications [6][10][11][12][13][14][28]. In the present study, the thermal stability of the new dispiro-1,3,4-thiadiazolines 2c and 2d was tested in THF solution at a

Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions

• Himani Malik,
• Sudha Devi,
• Debapriya Gupta,
• Ankit Kumar Gaur,
• Sugumar Venkataramani and
• Thiruvancheril G. Gopakumar

Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112

• particularly notable at positive sample voltage compared to negative sample voltage. The exceptional stability of the states at ambient conditions provides an opportunity to use a single FNAAP molecule as an 8-bit operation unit, with a potential storage capacity of ≈200 Tbits per 1 cm2 area using an

• imparted quantitative and reversible photoswitching [20][21]. The long-term photoswitching stability and tunable half-lifes of Z isomers of azopyrazole-based switches [20][21][22] have made their way to several applications in thermal energy storage [23], photoswitchable inhibitor [24], photoswitchable

• surface at ambient conditions. The fluorine substitution is chosen in FNAAP for its better photoisomerization efficiency (in solution as well as in solid state) and higher molecular stability [29]. Possible photoisomers of FNAAP, EEE, EEZ, EZZ and ZZZ are shown in Figure 1. FNAAP molecules assemble into

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

• (Scheme 3 and Supporting Information File 1, supplementary note 2). Our experiments clearly demonstrated that electron-poor aryls gave better yields in case of both symmetrical and unsymmetrical iodonium salts. In general, such results cannot be associated with the stability of radical species, which does

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• containing one or two exocyclic olefin units. Owing to the transformation of carbonyl groups, the resulting products exhibit several unique physical and chemical properties: (1) the enhancement of configurational stability, (2) the appearance of fluorescence, and (3) the reductive carbon–carbon-bond

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

• incorporating dual heptagonal rings [37]. Compound 23a exhibits dynamic chirality, aggregation-induced emission (AIE), and intense CPL (|glum| = 1.7 × 10−2), whereas compound 23f, with lateral π-extension, shows enhanced thermal stability and green emission at 517 nm (Table 7). Kuehne and co-workers reported

• EQE exceeding 36%, and operational stability with an LT95 of approximately 400 h at 10,000 cd m−2. These findings underscore the efficacy of B–N covalent integration in helicene-based frameworks for realizing high-efficiency, spectrally optimized, and robust red CP-OLED emitters. In 2022, Yang and co

• illustrating how subtle atomic substitutions can significantly influence the conformational stability of helical molecules (Table 19). These studies illustrate how precise heteroatom modulation enables fine control over CPL directionality and emission lifetimes, offering promising avenues for the development

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• , printing, and coloring agents for various materials, due to their excellent color fastness, high stability, and ease of synthesis. The azo functionality allows for a wide range of colors to be achieved by altering the substituents on the azo group, improving the color intensity, lightfastness, and wash

• E/Z isomerization around the C=N bond leads to reduced efficiency of the tautomeric based switching [52]. In this respect, based on the excellent stability of the azo compounds, it is interesting to understand the effect of the competitive proton transfer and E/Z switching by replacement of the

• stability of KE and KK (and hence, low values of ΔE(KE-E) and ΔE(KK-K)), but the increased number of CN substituents leads to a rise of ΔE(KE-E) and ΔE(KK-K) and, also, to the requested stabilization of K. Considering the data in Table 2, there is no compound that nears to the ground-state PES, requested

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• (Figure 2) [10][11][12]. As for the analogy to carbonyls, oxetanes display comparable polarity, spatial arrangement of the oxygen lone pairs and hydrogen-bond-accepting ability. In addition, they possess one major advantage and that is greater metabolic stability: while carbonyl groups are susceptible to

• methyls with an oxygen atom effectively eliminates its lipophilic character and reduces susceptibility to metabolic attack, while practically maintaining the molar volume. Because controlling polarity and metabolic stability is a major issue in medicinal chemistry, 3-substituted oxetanes have eventually

• an alkoxide anion producing an ether (Scheme 2) [35]. Although this seems to be a relatively simple, straightforward reaction, the yields are often low due to the competing Grob fragmentation (Scheme 2) which, besides being entropically favoured, might also be favoured by the thermodynamic stability

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

• azulene-embedded dione 59 in 39% yield. Finally, NaBH4 reduction followed by SnCl2/AcOH dehydration gave target non-alternant isomer of hexacene 60 in 43% yield. Interestingly, for the same number of rings, azulene-embedded acene isomers isomers exhibit greater stability than their fully benzenoid acene

Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers

• Kenichi Kato,
• Tatsuki Hiroi,
• Seina Okada,
• Shunsuke Ohtani and
• Tomoki Ogoshi

Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95

• conditions (Figure 2a). Insoluble solids, [3.3.3]_branch and [4.3.3]_branch, were obtained due to formation of bonding networks and washed repeatedly with CH2Cl2, H2O, and acetone. Characterization of methylene-alternating copolymers The thermal stability of the oligomers and polymers were evaluated with

• ° (Supporting Information File 1, Figure S601) and continuous curves in differential scanning calorimetry (DSC) between −70 and 300 °C (Figures S701 and S702, Supporting Information File 1). The results indicated that the polymers were amorphous while giving relatively high thermal stability toward phase

Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups

• Julius Seumer,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94

• carbon–hydrogen (C–H) bonds represent a fundamental challenge in modern organic chemistry, particularly because of the inherent stability and prevalence of these bonds in organic molecules. These bonds, which typically exhibit bond energies ranging from 90 to 110 kcal·mol−1, constitute the majority of

• meaningful correlation between thermodynamic stability and kinetic accessibility, as expressed by the BEP principle. Although this principle has been successfully applied in many cases, the correlation between reaction energies and activation barriers is often imperfect. For instance, studies on hydrogen

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

• 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

• that contributes to the overall aqueous solubility and stability of AuCl4−. The precipitation method, according to the authors, is postulated to involve acid hydrolysis of the acetal group of thiolated β-CD to form a reactive aldehyde that takes part in the reduction of the Au3+ cations that get bound

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

• pharmacokinetics [15][16], stability against degradation [17] and general stability [10][18] of the peptide [19]. One of those amino acids is pipecolic acid [20][21], a homolog of proline with a six-membered piperidine ring. Pipecolic acid has similar features as proline in regard to its rigid nature and turn

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

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

• carbon nanomaterials category in view of their stability, water affinity/dispersibility, and low toxicity [1][2][3][4]. Such nanomaterials significantly absorb in the 280–350 nm region due to a wide range of π–π* (C=C) and n–π* (C=O) transitions in both the core and on the surface of the particles. CDs

• recourse to treatments such as pyrolysis, ultrasonic carbonization, hydrothermal, solvothermal, or microwave irradiation [13][14][15][16][17]. The properties of CDs can be tuned by doping them with various elements, which influence photophysical and electrochemical properties, stability, and

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

• enamides as nucleophiles, rendering them more stable than enamines. This stability is reflected in their frequent occurrence in natural products [4]. As a result, research on the synthetic applications of enamides has historically lagged behind that of enamines [5][6]. Beyond their use in hydrogenation

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

• Ulm, Germany 10.3762/bjoc.21.80 Abstract Organic radicals with light-emitting properties and exceptional stability offer exciting opportunities to address spin-statistical limitations in organic electronics and advance quantum technologies. These radicals, acting as small molecular magnets, exhibit

• . Only at temperatures as low as 90 K, the monoradical is stable, allowing recording of the absorption and emission spectra [30]. Symmetrical halogenation of the triphenylmethyl (or trityl) unit increases stability of the molecule, compared to the parent unsubstituted trityl radical first reported by

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

• ], and dyes [15][16] serve as promising structures for constructing and designing novel PCs. These structures show a high electron affinity, stability, and the possibility of tuning their physicochemical properties by substituting the two aromatic rings. In 2018, Sang Kwon and co-workers reported a

• promising redox potentials in their excited states, indicating their potential to function as effective bimodal photocatalysts. Additionally, our photophysical characterization provided essential insights into their behavior in the excited state and stability. We initiated the study of the photocatalytic