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

• ) presence of a substituent (Br or Me) at the position adjacent to the vinyl group in the clockwise direction, (2) absence of a substituent other than hydrogen at the position adjacent to the vinyl group in the counterclockwise direction (CH or P). The substituent adjacent to the vinyl group (marked in red

Molecular tweezer–peptide conjugates disrupt the protein–protein interaction between survivin and histone H3 essential in mitosis

• Catherine Gsell,
• Philipp Rebmann,
• Karina Opara,
• Christine Beuck,
• Peter Bayer,
• David Bier,
• Ingrid R. Vetter and
• Thomas Schrader

Beilstein J. Org. Chem. 2026, 22, 557–567, doi:10.3762/bjoc.22.41

• the peptide tweezer 1 on either K-121 or K-129 (bottom). The positive residues of the H3 peptide are bound to the negatively charged area (red) whereas the phosphorylated threonine contacts a positively charged area, as known from the existing crystal structures. The tweezer moiety can associate with

• complex. A) Lewis structure of the truncated tweezer peptide monophosphate 2b. B) Close-up of the binding motif formed by 2b (tweezer: green, butynyl ester: red) on the survivin surface encapsulating Lys-121 after MD simulation (Desmond, 100 ns, 300 K, 0.15 mM NaCl) using explicit water solvent. A

• red, tweezer green. A) Lewis structures of the new slightly extended binding peptide 3b and the respective click conjugates with butynyl tweezer, mono- and diphosphate 2c and 2d. B) Lewis structures of the new binding peptide 3c and the resulting mono- and diphosphate tweezer conjugates 2e and 2f

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• variation often leads to a red-shifted absorption, the half-lives of the corresponding quadricyclanes are often decreased at the same time. In particular, the addition of an acetylene unit between the linking aromatic part and the norbornadiene often leads to short half-lives [29][30][31]. As arene-linked

• the photoreaction of 1f; blue: 1f; purple: 2f2,1; pink: 2f1,2; red: 2f0,3. Photochromic reaction of norbornadiene (1a) and quadricyclane (2a) and selected physicochemical properties; λonset = low-energy zero onset of absorption of 1a; t1/2 = half-life of 2a; ΔH = reaction enthalpy of the

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

• using thin-layer chromatography, with the appearance of the characteristic red spot upon treatment with FeCl3 confirming the presence of the hydroxamic acid functionality. Moreover, the formation of the tetra-hydroxamic acid product was confirmed by 1H NMR spectroscopy in deuterated DMSO, as evidenced

• leaching into water was confirmed by depositing a drop of the aqueous supernatant on a TLC plate, which showed no formation of the characteristic red iron-hydroxamate complex upon treatment with FeCl3. These physicochemical properties precluded standard liquid–liquid extraction but were suitable for a

Synthesis of a HDAC inhibitor–nanogold probe for cryo-EM visualization in class I HDAC co-repressor complexes

• Wiktoria A. Pytel,
• John W. R. Schwabe and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2026, 22, 480–485, doi:10.3762/bjoc.22.35

• . Error bars represent ± S.E.M. (n = 3). For full assay conditions see Supporting Information File 1. Final round of 2D classification of the cross-linked CoREST complex in the presence of Au–(CI-994) (87,649 particles). Red arrows indicate the position of the Au–(CI-994) probe localized with the CoREST

Synthesis and stereochemical analysis of dynamic planar chiral oxa[7]orthocyclophene

• Yukiho Hashimoto,
• Yuuya Kawasaki,
• Kazunobu Igawa and
• Katsuhiko Tomooka

Beilstein J. Org. Chem. 2026, 22, 436–442, doi:10.3762/bjoc.22.30

• alkyne 6. Subsequent preparation of the lithium acetylide using n-BuLi, followed by treatment with formaldehyde, afforded propargyl alcohol 3a in 70% yield over three steps. The reaction of 3a with Red-Al generated a vinyl aluminum species, which was then treated with iodine to provide the iodinated Z

Synthesis and anti-cancer activity of naphthalimide–organylselanyl conjugates

• Rajkumar Ravi and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2026, 22, 416–435, doi:10.3762/bjoc.22.29

• concentration of 2 × 10−5 M, as shown in Supporting Information File 1, Figure S21. Both compounds have slightly similar absorption bands. Compound 7 shows an absorption maximum at 395 nm as a broad band peak. In comparison to compound 7, compound 8 displays a slight bathochromic (red) shift, with absorption

• analysis provides vital insights into the electronic characteristics of atoms within a molecule [61]. In the MEP maps, the colour distribution follows the order blue, green, and red, representing increasing electrostatic potential. The blue regions correspond to more electropositive areas, while the red

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

• ]arenes by joining propargyl/2-azidoethyl and p-amino groups on a common platform. Parts of 1H,13C HMBC spectra of calixarenes 12 (a) and 13 (b) recorded in CDCl3 solutions at 600 MHz. Red lines show the key correlations between signals from the calixarene narrow-rim substituents and aromatic units

Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• ]helicenes 5a and 5b in chloroform (1 × 10−5 M) were recorded and compared with those of the corresponding oxaza[7]helicenes 6a and 6b (Figure 4A and 4B). As expected, extension of the helical π-systems in 5 leads to enhanced conjugation relative to 6, manifested in red-shifted absorption and emission bands

• and second fractions of the chiral HPLC analysis were assigned as the (P)- and (M)-enantiomers, respectively, for all 5a,b and 6a,b. As expected, the increase in helical length (n) from 7 to 8, 5a and 5b exhibited more red-shifted maximum |gabs| values at around 350 nm, whereas 6a and 6b showed values

• dashed lines for (P)-configuration of 5a (black), 5b (blue), 6a (green), and 6b (red). Recent examples of hetero[8]helicenes: (A) symmetric hetero[8]helicenes; (B) unsymmetrical hetero[8]helicenes; (C) short-step electrosynthetic access to new unsymmetrical oxaza[8]helicenes. Short-step synthesis of

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• CrystalExplorer 21.5 [55]. On the Hirshfeld surface, color coding indicates the nature of intermolecular interactions: red highlights contacts shorter than the van der Waals radius, white represents distances equal to the van der Waals radius, and blue denotes contacts longer that the van der Waals radius. Figure

•  4 shows front and back views of the Hirshfeld surfaces (dnorm) for compounds 4b and 4c. The Hirshfeld surface for compound 4b with dnorm map plotted (ranging from −0.8499 (red) to 1.4229 (blue) a.u.) is presented in Figure 5. Analysis of the HS revealed the presence of several intermolecular

• one of the water hydrogens interacts with a carbonyl group of the barbiturate ring (C=O···H–O = 2.867 Å). The HS for compound 4c with dnorm map plotted (ranging from −0.6673 (red) to 1.4313 (blue) a.u.), is shown in Figure 6. The dnorm map highlights key intermolecular interactions (marked in red

Conformational analysis of difluoromethylornithine: factors influencing its gas-phase and bioactive conformations

• Matheus P. Freitas

Beilstein J. Org. Chem. 2026, 22, 237–243, doi:10.3762/bjoc.22.17

• )/CBS level of theory. Color labels: H = white, C = grey, N = blue, O = red, F = electric blue. (S)-DFMO bound within the active site of human arginase I obtained from the Protein Data Bank (3GN0) (https://doi.org/10.2210/pdb3gn0/pdb, [21]). Dotted lines represent hydrogen-bonding interactions with

• amino acid residues and water molecules, while the ligand is delineated by a contour line to distinguish it from the binding cavity. Lowest-energy type-I, type-II, and type-III conformers of the zwitterionic form of (S)-DFMO. Color labels: H = blue, C = pink, N = orange, O = red, F = yellow. DFT

Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF

• Ruiyan Wang and
• Yunan Wu

Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16

• essentially unchanged, whereas its fluorescence emission undergoes a monotonic red shift with increasing solvent polarity (or polarizability), accompanied by an enlarged Stokes shift – a typical solvatochromic behavior. The weak solvent dependence of the absorption spectra indicates that the difference in

• the ground state, lowering the excited-state energy and thus the photon energy, which manifests macroscopically as a red-shifted emission. In polar media, the oriented polar solvent shell stabilizes the CT state more effectively than the ground or locally excited (LE) state, further decreasing the

• a result of RTP, as the sub-second lifetime and the pronounced thermal quenching behavior are characteristic features of RTP. Additionally, the red shift observed in the delayed emission spectrum compared to the steady-state emission is consistent with the behavior of lower-energy emissions that are

Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH

• Adrian G. Rossebø,
• Hannah G. Kolberg,
• Anders E. Tønder,
• Louise Kjaerulff,
• Poul Erik Hansen,
• Karla A. Frydenvang,
• Jesper Østergaard and
• Jesper L. Kristensen

Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11

• recrystallized from ethanol (Figure 3, purple), a similar pattern is observed, indicating a high degree of crystallinity. Furthermore, samples of 1·HCl prepared either by rapid precipitation in organic solvents, as described in the Experimental section (red), or material isolated from a saturated solution of 1

• , oxygen atoms red, and chloride ion green. b) The crystal packing reveals alternating layers, a polar layer with hydrogen bonds (black dashed lines), and a hydrophobic layer with π–π-stacking (grey dashed lines). SCXRD and XRPD spectra of different preparations of 1·HCl. Blue: SCXRD spectrum of 1·HCl. Red

• , green, and purple: XRPD spectra of 1·HCl after recrystallization (red), directly as synthesized (green), and of a slurry obtained by stirring excess solid in ultrapure water for 3 days (purple). TGA and DSC thermograms of 1·HCl. Calculated pH-dependent species distribution curves for 25CN-NBOH (1). a

A new synthesis of Tyrian purple (6,6’-dibromoindigo) and its corresponding sulfonate salts

• Holly Helmers,
• Mark Horton,
• Julie Concepcion,
• Jeffrey Bjorklund and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2026, 22, 167–174, doi:10.3762/bjoc.22.10

• red shift by 16 and 15 nm with a moderate increase in molar absorptivity, respectively, for compounds 9 and 10 [29]. This means that to the human eye, di- and trisulfonated derivatives of 1 appear blue, not purple. A smaller shift in λmax is observed when indigo is sulfonated, allowing for its blue

Design and synthesis of an axially chiral platinum(II) complex and its CPL properties in PMMA matrix

• Daiki Tauchi,
• Sota Ogura,
• Misa Sakura,
• Kazunori Tsubaki and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2026, 22, 143–150, doi:10.3762/bjoc.22.7

• -derived pendant group, which exhibited aggregation-enhanced red phosphorescence and CPL properties in the solid states [20], while Yam and co-workers also reported pincer-type platinum(II) complexes containing chiral amine moieties, and investigated their aggregation behavior and chiroptical properties

Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection

• Ergin Keleş,
• Alberto Barsella,
• Nurgül Seferoğlu,
• Zeynel Seferoğlu and
• Burcu Aydıner

Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6

• can be shifted in the deep red/NIR region by changing the donor group with increased conjugated systems [19][20][21][22]. Gupta et al. studied optical properties of D–π–A system-based indan-2-one derivatives, and symmetric derivatives showed a significant bathochromic shift (≈300 nm) compared to

• more polarized than the ground states, as shown by the positive observed μβ values. Moreover, both the ground and excited states were polarized in the same direction for all studied compounds. The standard reference is Disperse Red 1 (μβ = 450 × 10−48 esu) [33]. Comparing the µβ values of Disperse Red

• 1 with the measured values of 2a–c shows that the molecules exhibited a higher NLO response than Disperse Red 1, except for 2c. The dipole moment (μ), polarizability (α), first-order hyperpolarizability (β), and its components, which were calculated at the B3LYP/6-31+G(d,p) level of theory in CHCl3

One-pot synthesis of ethylmaltol from maltol

• Immanuel Plangger,
• Marcel Jenny,
• Gregor Plangger and
• Thomas Magauer

Beilstein J. Org. Chem. 2025, 21, 2755–2760, doi:10.3762/bjoc.21.212

• Immanuel Plangger Marcel Jenny Gregor Plangger Thomas Magauer Department of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, Innrain 80−82, 6020 Innsbruck, Austria Red Bull Central Laboratory, Betriebsgebiet Hängender Stein 1, 6713 Ludesch, Austria Red Bull Service

• Laboratory of Red Bull Service GmbH and was found to meet the quality parameters of commercial ethylmaltol (1), posing no concerns from a food safety perspective (see Supporting Information File 1). Conclusion In conclusion, we have developed a new synthetic approach to the flavor enhancer ethylmaltol (1

Sustainable electrochemical synthesis of aliphatic nitro-NNO-azoxy compounds employing ammonium dinitramide and their in vitro evaluation as potential nitric oxide donors and fungicides

• Alexander S. Budnikov,
• Nikita E. Leonov,
• Michael S. Klenov,
• Andrey A. Kulikov,
• Igor B. Krylov,
• Timofey A. Kudryashev,
• Aleksandr M. Churakov,
• Alexander O. Terent’ev and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2025, 21, 2739–2754, doi:10.3762/bjoc.21.211

• 0.01 M solutions of 1-nitro-1-nitroso compounds 1a, 1f, 1c, and 1i in MeCN, these substances do not undergo noticeable oxidation up to +2.4 V. On the other hand, 1-chloro-1-nitrosocyclohexane (S3, green curve) and 1-nitrosocyclohexyl acetate (S4, red curve) are oxidized at +1.82 V and +1.77 V

• our study [87], ADN exhibits two irreversible oxidation peaks (red curve) at +1.8 V and +2.1 V, which are higher than or comparable to those of S2–S4 (Figure 2). Upon the addition of ADN to a solution of 1a (Figure 2, green curve), a single oxidation peak was observed at +1.89 V. Finally, the reaction

• ]/CPCM(MeCN) level of theory (in the case of >15 conformers, 15 most stable according to GFN2-xTB were analyzed). CV-curves of 0.01 M solutions of a) 1a (blue), b) 1f (azure), c) 1c (pink), d) 1i (yellow), e) S4 (red), f) S3 (green), g) S2 (brown), and h) S1 (orange) in 0.1 M n-Bu4NBF4 solution in MeCN

Recent advancements in the synthesis of Veratrum alkaloids

• Morwenna Mögel,
• David Berger and
• Philipp Heretsch

Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206

• of green for strategic connections, yellow for neutral, e.g., functional group interconversion and isomerization, orange for non-strategic reactions, and red for protecting group (PG) manipulations (Scheme 3). Protecting group manipulations refer to any protection or deprotection of a functional

• and as a semisynthesis, poses some non-strategic redox transformations (orange) and protecting manipulations (red) especially in the beginning and in the endgame of the synthesis. Nevertheless, several transformations are desirable green transformations, although it is noticeably more difficult to

• the semisynthesis of Liu/Qin [26] 15 years later. The only non-green transformations displayed at the start were a protecting group installation (red) and a condensation (yellow), which was needed for the C–H activation (light green). All other transformations connect either C–C or C–heteroatom bonds

Synthesis of new tetra- and pentacyclic, methylenedioxy- and ethylenedioxy-substituted derivatives of the dibenzo[c,f][1,2]thiazepine ring system

• Gábor Berecz,
• András Dancsó,
• Mária Tóthné Lauritz,
• Loránd Kiss,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2645–2656, doi:10.3762/bjoc.21.205

• to 0–5 °C, and SnCl4 (47.28 g, 182 mmol, 21.2 mL) was added to the reaction mixture. The red suspension obtained was stirred at 0–5 °C for 1 h, then at room temperature for 2 h. It was poured onto a mixture of crushed ice (1500 g) and conc. hydrochloric acid (200 mL). It was stirred while warming to

Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• values ranging between 409–426 nm. In general, the solvatochromic effect of these compounds showed a blue shift in EtOAc, and a red shift in MeCN. The fluorescence emission spectra of these compounds revealed a strong blue to green fluorescence emission, with the maximum emission peaks varying from 535

• to 573 nm for compound 3n and from 479 to 524 nm for compound 4n. Therefore, the fluorescence emission spectra demonstrated a clear dependence on solvent polarity and the maximum emission wavelength λem. Thus, a red shift in the emission bands was observed in solvents with higher polarity, indicating

• observed, however, with an increase in fluorescence emission. Interestingly, in DMSO, a bathochromic effect was observed alongside a significant increase in fluorescence intensity. In aqueous medium, a pronounced red shift was verified, likely due to stabilization of the excited state by water molecules

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• is reductively quenched by arene 16, producing the corresponding aryl radical cation C and 3CzCIIPN•– (E1/2 red = +1.56 V vs SCE). PC•– then reduces the azolium ion A (E1/2 = −0.81 V vs SCE) to generate the ketyl radical B, thereby closing the photoredox catalysis cycle. 2-Methoxynaphthalene produced

• photocatalysts such as fluorescein, alizarin red S, rhodamine B, and eosin Y. Since photoexcited organophotocatalyst rhodamine 6G (Rh6G*) possesses a sufficiently positive reduction potential in its singlet excited state S1 (Ered* = +1.18 V vs SCE*). The reduced form of Rh6G•– subsequently reduces BrCCl3 to

Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles

• Kaylen D. Lathrum,
• Emily M. Hanneken,
• Katelyn R. Grzelak and
• James T. Fletcher

Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194

• -connected ortho-bromobenzene subunit analogs failed under microwave irradiation but were successful using conventional thermal heating in yields of 31–65%. The expanded nature of the aromatic ring system following annulation was reflected by the downfield shifting of aromatic 1H NMR signals and the red

• general red-shifting of UV absorbance signals for the annulated pentacycles presented in Table 1 relative to their non-annulated counterparts, further indicating an aromatic π-system expansion upon annulation. Similar trends were observed for those compounds shown in Table 2 (Figure S1, Supporting

Isoorotamide-based peptide nucleic acid nucleobases with extended linkers aimed at distal base recognition of adenosine in double helical RNA

• Grant D. Walby,
• Brandon R. Tessier,
• Tristan L. Mabee,
• Jennah M. Hoke,
• Hallie M. Bleam,
• Angelina Giglio-Tos,
• Emily E. Harding,
• Vladislavs Baskevics,
• Martins Katkevics,
• Eriks Rozners and
• James A. MacKay

Beilstein J. Org. Chem. 2025, 21, 2513–2523, doi:10.3762/bjoc.21.193

• PNA oligomer with the N-(2-aminoethyl)glycine backbone (in red); (b) Representative monocyclic synthetic nucleobase triples through Hoogsteen hydrogen bonding (blue dashed lines). Watson–Crick hydrogen bonds are in red (dashed lines). Representative extended nucleobase triples through Hoogsteen

• hydrogen bonding (blue dashed lines). Watson–Crick hydrogen bonds are in red (dashed lines). Evolution of the strategy for U–A recognition. Isoorotamide-derived nucleobases for A–U recognition. Proposed isoorotamide distal binding (Db) nucleobases designed from the Io5 core. Hydrogen bonding donors to the

• linker are highlighted in red. Sequences for RNA hairpins and PNA ligands used for binding studies. Major-groove view of hydrogen-bonding interactions in the (A) Db1*U–A triplet, (B) Db2*U–A triplet, (C) Db2*C–G triplet, and (D) Db3*U–A triplet. Carbon, hydrogen, oxygen, and nitrogen are labelled in

Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• free energies were calculated at the B3LYP-D3/def2-tzvp//B3LYP/6-31G(d) level in MeCN. b) Spin density of IN4 (isovalue = 0.004). c) IRC analysis of TS2 (red line) and bond-length changes of C19–C3 (yellow line) and C19–C12 (blue line) along IRC path. d) Mayer bond order changes of selected structures