Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• dichromate in acidic solution or with potassium permanganate in acidic or alkaline solution led to complete decomposition of the melifoliones. A solution of the melifoliones in methanol with addition of methylene blue decomposed completely into undefined products within 24 hours when exposed to sunlight and

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

• mass, indicating decomposition above this temperature (see Supporting Information File 1, Figure S3). The cycloreversion of trisquadricyclane 2f0,3 was also initiated in a ground-state reaction with magic blue (5), which has already been shown to be an effective catalyst for this reaction [46][47][48

• ]. Upon addition of magic blue (5, 7.5 mol %) to a solution of quadricyclane 2f0,3 in CDCl3, the norbornadiene 1f was formed almost quantitatively in addition to very small traces of tri(4-bromophenyl)amine, i.e., the reduced catalyst (see Supporting Information File 1, Figure S12). Discussion A

• 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 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

• 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

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

• 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

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• 29d (presilphiperfolan-8-yl cation), a precursor which was invoked to be involved in the biosynthesis of various sesquiterpenes. Two noteworthy examples are given here: either of the two 1,2-alkyl shifts of the cyclohexane accomplishes ring contraction. Following the blue arrow in the structure of 29d

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

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

• ·HCl in ultrapure water (blue), gave comparable diffractograms, indicating the presence of a single polymorph. Differential scanning calorimetry (DSC) showed a sharp endothermic peak corresponding to a melting point of 219.0 ± 0.1 °C (with ΔfusH = 50.4 ± 1.1 kJ/mol) for 1·HCl (Figure 4), and

• , Et3N, 4 Å molecular sieves, EtOH, rt, 1.5 h, then NaBH4, 0 °C to rt, 1.2 h, then HCl, 74%. a) Single-crystal X-ray structure of 1·HCl. Displacement ellipsoids of the nonhydrogen atoms are shown at the 50% probability level. Hydrogen atoms are shown as spheres of arbitrary size. Nitrogen atoms are blue

• , 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

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

• indigo derivatives, an increasing number of sulfonic acid groups results in greater solubility of the 6,6’-dibromoindigo derivative (e.g., 10 has greater solubility in water than 9) [25]. When dissolved in aqueous solution, both 9 and 10 yield a bright blue solution. As shown in Figure 1A, salt 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

• (LL’CT) and metal-to-ligand charge transfer (MLCT) character. Photoluminescence measurements in CH2Cl2 solution revealed dual emission peaks at 427 nm and 596 nm, with a quantum yield of 3%. In PMMA matrix, the emission peaks were blue-shifted to 408 nm and 558 nm, and the quantum yield slightly

• blue-shifted by 38 nm, and the shorter-wavelength emission peak (408 nm) was blue-shifted by 19 nm. These blue shifts are attributed to the hydrophobic environment in the PMMA matrix. In such low‐polarity surroundings, the excited state is less stabilized, resulting in a higher excited‐state energy and

• thus a blue‐shifted emission. The PLQY in the PMMA matrix was 4%, comparable to that observed in solution. In the film, the emission lifetimes could be fitted with double- or triple-exponential functions, resulting in fluorescence components of 0.49 ns (50%) and 0.48 ns (50%) at 408 nm, and

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

• also showed significant color changes with increasing polarity. Color changes of 2a; from purple to blue, 2b; blue to green, and 2c; pale orange to pale pink (Figure 2d). Dyes do not show any significant emission. Chemosensor properties Cyanide selectivity study The dyes 2a–c could have the ability to

• groups is disrupted. These results strongly suggest the addition of cyanide to the vinyl bridge. Furthermore, the color of dyes 2a–c, blue, green, and pink, respectively, under ambient light changed to yellow when interacting with cyanide. The interaction mechanism was determined by 1H NMR, and the

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

• ]/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

• on a working glassy-carbon electrode (d = 3 mm) under a scan rate of 0.1 V/s at 298 K. CV-curves of 0.01 M solutions of a) 1a (blue), b) ADN (red), c) the mixture of 1a and ADN (green), d) 2a (pink) in 0.1 M n-Bu4NBF4 solution in MeCN on a working glassy-carbon electrode (d = 3 mm) under a scan rate

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

• . The skeleton is marked in blue for batrachotoxin A (1) [3], cyclobuxin D (2) [4], latifolinin (3) and solanidine (5) [5]. In samandarin (4) [6], the A-ring consists of a seven-membered nitrogen-containing ring (marked in purple), but the BCD-framework remains unchanged. The representative Veratrum

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

• from rhodanine (3n) exhibited an intense absorption band in the range of 462–481 nm, related to the π→π*-type transitions. Additionally, weaker, broad absorption bands were observed below 350 nm. In contrast, the thiazolidine-2,4-dione derivative 4n displayed a blue shift, with maximum absorption band

• 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

• experimental spectrum. In blue, suppressed or absent carbon atoms bound to hydrogen atoms. a) Visual impressions of the solvatochromic study in various solvents (10−5 M) after excitation with a natural light. b) UV–vis absorption spectra of 3n in different solvents (10−5 M) at room temperature. c) Normalized

Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water

• Michaela Šusterová and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201

• ] (0.5 mM) with increasing amount of BU1. C) UV–vis spectra of K[Au(CN)2] (0.5 mM) before and after additions of supernatants obtained by treatment of SG-NHCO-BU1 and SG-BU1 with aqueous 1 M KOH. The efficiency of materials (blue SG-BU1, grey SG-NHCO-BU1) in sorbing dicyanoaurate from its water solution

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

• higher oxidation potential (E1/2 = +1.52 V). This reaction was examined using different solvents, and it was found that toluene and 1,4-dioxane gave low yields (4–5% yield). Under blue LED irradiation, Ir-based PC is photoexcited, and its excited state is reductively quenched by the electron-rich arene

• for 18 h (Scheme 6) [56]. Gao, Ye, and co-workers reported the iminoacylation of alkenes 17 via photoredox NHC dual catalysis in the presence of NHC (20 mol %), photocatalyst (5 mol %), with Na2CO3 (1.2 equiv) using a 36 W blue LED. In this method, the alkene-attached iminyl radicals A and the NHC

• and heteroarenes using blue LED. Asymmetric synthesis of fused pyrrolidinones via organophotoredox/N‑heterocyclic carbene dual catalysis. Acknowledgements Vasudevan Dhayalan expresses his appreciation to DST-SERB for core research grant (CRG/2022/001855), and to the National Institute of Technology

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• perhydrofuropyran core highlighted in blue). Synthetic strategies toward malayamycin A. (A) Previous synthetic route. (B) Our strategy toward the core skeleton. Rational for intramolecular dipolar cycloaddition. Proposed pathway for the enone formation. Modified route to access the core of malayamycins. Attempting

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

• control compounds 37–42 (blue lines) in acetonitrile solvent. Synthesis of pentacyclic aromatic heterocycles from varying alkynes.a Synthesis of pentacyclic aromatic heterocycles from varying azides.a Summary of UV–vis absorbance/emission signals. Minimum inhibitory concentration assay results.a

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

• green, white, red, and blue, respectively. Synthesis of the Db1 monomer (8). Synthesis of Db2 monomer 15. Synthesis of Db3 monomer 21. Microwave promoted optimization of glutaric anhydride opening with 12a. Binding dataa for PNA containing Db monomers using UV thermal meltingb and isothermal titration

Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• strips) or 467 nm light (blue strips), and after 5 minutes post-irradiation. b) Percentage of sulforhodamine B released from LUVs containing axle 3 upon ten light irradiations at either 370 nm or 467 nm. Green strips represent one minute of irradiation at either wavelength. c) Changes in absorbance of

• EYPC/Chol 8:2 LUVs containing axle 3 upon five irradiation cycles. The absorbance was measured before and after 1 minute irradiation at 370 nm light and 467 nm light alternately, where the blue trace corresponds to the absorption after the last irradiation at 467 nm. d) Changes in absorbance of EYPC

• five alternating light-irradiation cycles. The fluorescent emission of sulforhodamine B was measured before and after 1 minute irradiation with 370 nm light (pink strips) or 467 nm light (blue strips), and after 5 minutes post-irradiation. The sulforhodamine B (10 mM) was encapsulated in LUVs composed

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

• catalysts that could promote the proposed PET reaction of 9a on the basis of our previous results [15]. The reaction was performed in MeCN in the presence of photocatalysts under blue light-emitting diode (LED) irradiation at 30 °C. The results are listed in Table 1. Catalysts I [28], II [29], and III [30

• 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

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• blue LEDs at room temperature constructed a single diastereoisomer 23 in 90% yield. From 23, the ABCDE pentacyclic skeleton of phainanoids (27) was ultimately established via a Mitsunobu reaction, intramolecular nucleophilic substitution with in situ-generated aryllithium, and protecting group

• under blue LED irradiation. Solid-state reactions differ from solution-phase processes due to restraints on molecular motions imposed by the crystal lattice, thereby avoiding side reactions caused by unrestricted molecular motions in solution [41]. It has also been demonstrated that for crystalline 1,2

• pyrrolidine-derived phenyl keto amide substrate 91 with blue LEDs produces the pyrrolidine-fused 4-oxazolidinone (N,O-acetal) 92, precluding preparation of the pyrrolidine analog of lycoplatyrine A (94) by this method. Compound 92 is presumably formed via either the radical mechanism [41] or possibly

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• along with comparator H2 as solid-state sequestrants for a panel of five dyes (methylene blue, methylene violet, acridine orange, rhodamine 6G, and methyl violet 6B). We find that catechol-walled H2 (OH substituents) is a superior sequestrant compared to G2W1–G2W4 (OMe substituents). X-ray crystal

• structures for G2W1 and G2W3 suggest that the OMe groups fill their own cavity and thereby decrease their abilities as sequestrants. H2 achieved a removal efficiency of 94% for methylene blue whereas G2W1 demonstrated a 64% removal efficiency for methylene violet; both sequestration processes were largely

• textile, leather, paint, plastic, cosmetics, pharmaceuticals, and food industries [4]. It has been estimated that about 7 × 106 tons of dyes (e.g., methylene blue, rhodamine B, methyl orange, Congo red, disperse violet 26, methyl red, crystal violet) are produced annually worldwide [5]. Many dyes are

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• preparation of chiral β-aminoalcohols [63]. Chiral copper(I) complexes convert imidate radicals, formed transiently through energy-transfer catalysis, to oxazolines. The transformation includes a regioselective and enantioselective HAT process. Upon blue LED irradiation, oxime imidates (derived from alcohols

A chiral LC–MS strategy for stereochemical assignment of natural products sharing a 3-methylpent-4-en-2-ol moiety in their terminal structures

• Rei Suo,
• Raku Irie,
• Hinako Nakayama,
• Yuta Ishimaru,
• Yuya Akama,
• Masato Oikawa and
• Shiro Itoi

Beilstein J. Org. Chem. 2025, 21, 2243–2249, doi:10.3762/bjoc.21.171

• tool for the structural determination of diverse MPO-containing natural products in future studies. Representative natural products sharing the 3-methylpent-4-en-2-ol (MPO) moiety in their terminal structures, with the moiety highlighted in blue (assigned configuration) or yellow (undetermined