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

• microcrystalline solid, was observed to be bench-stable for several months when stored in a sealed glass scintillation vial under ambient atmosphere at room temperature. Using the mild Kornblum oxidation, 4-bromo-2-nitrobenzyl bromide (6) was converted into the desired 4-bromo-2-nitrobenzaldehyde (4). As shown in

Circumventing Mukaiyama oxidation: selective S–O bond formation via sulfenamide–alcohol coupling

• Guoling Huang,
• Huarui Zhu,
• Shuting Zhou,
• Wanlin Zheng,
• Fangpeng Liang,
• Zhibo Zhao,
• Yifei Chen and
• Xunbo Lu

Beilstein J. Org. Chem. 2026, 22, 158–166, doi:10.3762/bjoc.22.9

• efficiency of the S(=N)–O bond formation. Under the standard conditions (Table 1, entries 1–10), 1a (0.15 mmol) was treated in MeOH (2a, 1.0 mL, ca. 24.6 mmol; ca. 160 equiv relative to 1a) at room temperature. To improve the compatibility of the protocol with solid or high molecular weight alcohols, we

• moiety. PIDA-mediated approach versus the present NBS-mediated approach to sulfinimidate esters. Substrate scope of sulfenamides derived from various thiophenols and thiols. Reaction conditions: sulfenamide 1 (0.15 mmol), NBS (1.2 equiv), NaHCO3 (1.5 equiv), MeOH (1.5 mL), room temperature, 30 min

• . Yields are of isolated products. Substrate scope of sulfenamides derived from various amides. Reaction conditions: sulfenamide 1 (0.15 mmol), NBS (1.2 equiv), NaHCO3 (1.5 equiv), MeOH (1.5 mL), room temperature, 30 min. Yields are of isolated products. Substrate scope of reactions between sulfenamides 1a

Asymmetric Mannich reaction of aromatic imines with malonates in the presence of multifunctional catalysts

• Kadri Kriis,
• Harry Martõnov,
• Annette Miller,
• Mia Peterson,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2026, 22, 151–157, doi:10.3762/bjoc.22.8

• conversion of the starting imine within 3 hours at rt and in 5 hours at −20 °C. Decrease of the temperature increases the enantiomeric purity of the product (from 27% ee up to 52% ee) (Table 1, entries 1–3). The corresponding H-analogue of catalyst A was less selective (18% ee) (Table 1, entries 4 and 5

• stirred at room temperature until a suspension was formed (ca 5 min). After that, the reaction mixture was cooled to −20 °C. The malonic ester (0.171 mmol, 3.0 equiv) was added to the reaction vessel via syringe. The reaction was stirred at −20 °C for an appropriate time. The progress of the reaction was

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

• solutions (1.0 × 10−5 M) and 1 wt % PMMA matrices were acquired using a JASCO FP-8550 spectrometer at room temperature, at excitation wavelength of 300 nm (both solution and PMMA matrix). CPL spectra of CH2Cl2 solutions (1.0 × 10−5 M) and 1 wt % PMMA matrices were measured with a JASCO CPL-300

• spectrofluoropolarimeter at room temperature, at a scattering angle of 0° upon excitation with unpolarized, monochromated incident light. Absolute PLQYs of solutions and powder samples were determined using a JASCO FP-8550 spectrometer with an integrating sphere (JASCO ILF-533, diameter 96 mm) at an excitation wavelength

• (112 mg, 0.0962 mmol) and trimethylsilylacetylene (0.40 mL, 2.9 mmol) was added degassed solution of Et3N (2.6 mL, 19 mmol) and toluene (5.2 mL) by argon bubbling. The reaction mixture was refluxed at 90 °C for 21 hours. After cooling to room temperature, the reaction mixture was filtered through

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

• have higher polarizability values and dipole moments (μ) than 2c. TGA analysis Thermogravimetric analyses (TGA) were performed to determine the thermal stability of the dyes. The TGA method allows the determination of thermal and gravimetric changes in the material following temperature increases. Dyes

• , especially those with potential for use in optical systems, must be stable up to certain temperatures depending on the systems [34][35][36]. The percentage mass loss versus temperature graph is shown in Figure 8. The decomposition temperatures (Td) of the dyes are given in Table 5. Results show that the dyes

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• aromatic rings (Scheme 4) [48]. Using [Rh(nbd)Cl]2 and Pd/C as catalysts, aromatic hydrocarbons with various functional groups can be hydrogenated at room temperature and 1 atmosphere of hydrogen, thus simplifying the reaction operation and cost. Hydrogenation of fused aromatic rings Hydrogenation of the

• through sequential nucleophilic attack and intramolecular cyclization. (+)-Isomatrine was subsequently synthesized through catalytic hydrogenation via Rh/C, LAH reduction, and tertiary amine oxidation (Scheme 28). After synthesizing (+)-isomatrine, the effects of catalyst type, loading, temperature, and

• reaction parameters such as catalyst loading, solvent, reaction time, and temperature enabled the selective access to diverse hydrogenated products. These developments have established a valuable foundation for the total synthesis of indole-derived alkaloids, facilitating more concise and efficient

Advances in Zr-mediated radical transformations and applications to total synthesis

• Hiroshige Ogawa and
• Hugh Nakamura

Beilstein J. Org. Chem. 2026, 22, 71–87, doi:10.3762/bjoc.22.3

• properties [1]. Among its notable physical attributes is its high corrosion resistance: metallic zirconium is exceptionally stable toward acids and bases at ambient temperature and is less susceptible to corrosion than titanium. Its low toxicity and excellent biocompatibility have historically supported the

• tryptophan. The resulting radical species underwent fast dimerization to furnish the desired dimer 61. This zirconocene-catalyzed dimerization proceeded smoothly under remarkably mild conditions at room temperature, suggesting broad applicability. Indeed, the reaction was shown to tolerate a wide substrate

• potential and stabilizing the radical pathway. The DFT calculations are shown in Scheme 13A. The activation barrier for the XAT process was calculated to be ΔG‡ = 8.0 kcal/mol, indicating that this process can proceed spontaneously around room temperature. Moreover, the transition state (TS1) suggested the

Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene

• Dmitry N. Platonov,
• Alexander Yu. Belyy,
• Rinat F. Salikov,
• Kirill S. Erokhin and
• Yury V. Tomilov

Beilstein J. Org. Chem. 2026, 22, 64–70, doi:10.3762/bjoc.22.2

• transition states with an adjacent ester group, not to the stability of the main conformer. Conversely, the reactions with halogens and diazonium salts are immediate at room temperature and the α-selectivity, when observed, can be due to the stability of the main conformer. The transition from iodine to

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

• attracted our interest, prompting a more detailed investigation. Kinetic studies with acetophenone revealed an induction period prior to reaction onset (Figure 5). Elevated temperatures shortened the initiation time, whereas lower temperatures extended it to several hours. Both temperature and reaction time

• of the desired products (Scheme 20B). The authors proposed that BTC functions by regenerating benzoyl chloride in situ from benzoic acid, thereby allowing the use of benzoyl chloride in catalytic quantities (Scheme 20C). Under similar conditions – benzoyl chloride (2.2 equiv), room temperature

• principal difference being the use of 1,2-dibromoethane as solvent [150]. The reported substrate scope was comparatively narrow (not shown). Simultaneously, Liu demonstrated that FeCl3·6H2O could also serve as an effective Lewis acid when the reaction temperature was raised to 50 °C (Scheme 45) [151]. As in

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

• hypothesized that decomposition pathways including potential instability of dianion I were responsible for the low overall recovered mass balance. This could be improved by lowering the temperature to −20 °C, which increased the yield of ethylmaltol (1) to 46% along with 1% putative 6 and 10% recovered maltol

• (2) (Table 1, entry 4). Reducing the temperature to −30 °C had no significant effect on the reaction outcome (see Supporting Information File 1). Increasing the LDA equivalents even further enabled full conversion, however, in the process significant amounts of overalkylation products such as 7 (8

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

• a stirred solution of 2,2-dimethyl-5-nitro-5-(nitro-NNO-azoxy)-1,3-dioxane (2f, 1.00 g, 4.0 mmol) in MeOH (10 mL) at 25 °C. After addition, the reaction mixture was stirred at this temperature for 24 h (the completion of reaction was monitored by TLC). Then the solvent was removed in vacuo at 40 °C

• a mixture of acetic anhydride (3.4 mL, 36.0 mmol) and 100% nitric acid (0.6 mL, 13.2 mmol) at 0 °C, and the mixture was stirred at this temperature for 30 min. Then the reaction mixture was poured into ice-water (50 mL) and extracted with CH2Cl2 (3 × 20 mL). The combined organic phase was washed

Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones

• Svetlana O. Kushch,
• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess,
• Pavel A. Slepukhin,
• Alexandrina S. Volobueva,
• Vladimir V. Zarubaev and
• Victor I. Saloutin

Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209

• three nucleophilic centers in 1,3-diaminopropan-2-ol (3), and because there is a need to increase diastereoselectivity of the cyclization process. Table 1 presents the optimization steps for the reaction conditions at various solvents and temperature. The reaction course was monitored by TLC and 19F NMR

• %) (Table 1, entry 10), with the formation of the cis,cis-bicycle 4acc as the predominant product (28%), while the proportion of hexahydrooxazolopyridones 5 was minimal (10%) compared to all other conditions. The highest content of hexahydrooxazolo[3,2-a]pyridin-5-one 5a was observed at room temperature in

Tandem hydrothiocyanation/cyclization of CF₃-iminopropargyl alcohols with NaSCN in the presence of AcOH

• Ruslan S. Shulgin,
• Ol’ga G. Volostnykh,
• Anton V. Stepanov,
• Igor’ A. Ushakov,
• Alexander V. Vashchenko and
• Olesya A. Shemyakina

Beilstein J. Org. Chem. 2025, 21, 2694–2702, doi:10.3762/bjoc.21.207

• hydrothiocyanation of ynones using KSCN in AcOH at 70 °C. They also demonstrated that the adducts of ynones are readily cyclized in situ via a second thiocyanation to form thiazine-2-thiones at a slightly higher temperature and for a longer time. Meanwhile the reaction with ynamides led to decyanative amido

• MSCN/acid system. In comparison to ynamides [19] and alkynehydrazones [22], whose adducts cyclize with the involvement of nitrogen functional groups at elevated temperatures and extended reaction times, the reaction of CF3-substituted iminopropargyl alcohols occurred at room temperature within 15 min

• formation and ratio of the products in contrast to the substituents in the imine fragment. NMR monitoring of reactions (1a/NaSCN/AcOH or 1g/NaSCN/AcOH in MeCN) did not allow to detect any intermediates even when the temperature was lowered to 0 °C. In the 1H and 19F NMR spectra the signals of products 2a

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

• resulted in a hydroxy group, which was oxidized to furnish Nazarov precursor 54 in 52% yield. Key step of this sequence was the photoinduced excited-state Nazarov reaction, which involved irradiation of 54 in dichloroethane at 366 nm for 30 min at room temperature. Remarkably, this method had been

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

• amorphous character of the compounds exhibiting wide melting ranges (21b, 38d, 54f) were proven by XRPD measurements performed on a PANalytical Empyrean X-ray powder diffractometer at room temperature. Powder samples (without grinding) were placed between two Mylar foils in the sample holder at a reflection

• . Diffraction intensity was measured by a PIXcel 3D 1 × 1 area detector. Thermogravimetric (TG) curves of amorphous samples (21b, 38d, 54f) were measured by a TA Instruments Discovery TGA thermogravimetric analyzer in the 30–200 °C temperature range with a 10 °C/min heating rate using 11 to 12 mg sample in a

• 100 μL platinum pan in 25 mL/min nitrogen atmosphere. Melting properties of the amorphous samples (21b, 38d, 54f) were also studied by a TA Instruments Discovery DSC differential scanning calorimeter in the 25–120 °C temperature range with a 10 °C/min heating rate using 2.5 to 3.0 mg sample in a

Chemoenzymatic synthesis of the cardenolide rhodexin A and its aglycone sarmentogenin

• Fuzhen Song,
• Mengmeng Zheng,
• Dongkai Wang,
• Xudong Qu and
• Qianghui Zhou

Beilstein J. Org. Chem. 2025, 21, 2637–2644, doi:10.3762/bjoc.21.204

• final natural product rhodexin A in one step. Just as expected, when directly subjecting 16 to the abovementioned conditions, rhodexin A was indeed afforded albeit in only 10% yield. The required longer reaction time and elevated temperature to achieve deprotection of the sugar motif resulted in an over

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

• disubstitution processes involving sulfur-to-nitrogen displacement, likely promoted by the nucleophilic character of the amine. These limitations are likely due to the reaction conditions employed, including the high temperature and acidic environment, which may favor side reactions over the desired

• 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

• emission spectra of 3n in different solvents (10−5 M) at room temperature. d) Lippert–Mataga plot showing Stokes shift as a function of solvent orientation polarizability (Δf) for compound 3n. Photophysical study in aqueous solution under different pH values for compound 3n (10−5 M) at room temperature. a

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

• (Scheme 1). The latter reaction was also done using a 9:1 (w/w) ratio of a-SG to BU1, by treatment of a-SG with the macrocycle in DMF at ambient temperature (Scheme 1). The material was then isolated by filtration and washed with DMF and methanol. The prepared a-SG, SG-NHCO-BU1, and SG-BU1 materials were

• Silica gel (8.01 g) was dispersed in toluene (24 mL) and stirred under argon atmosphere, while heated up to 115 °C. Then, APTES (6 mL) was added, and the dispersion was stirred under inert atmosphere at elevated temperature for 5 h. After cooling, the dispersion was filtered, washed thoroughly with

• toluene, ethanol and acetone to remove unreacted APTES and dried in vacuo (50 °C) overnight in order to get a-SG [15][16]. Further, to prepare covalent SG-NHCO-BU1, a-SG (0.9 g) was suspended in DMF (15 mL) and shaken at ambient temperature for 30 min. BU1 (0.1 g, 1 equiv) was dissolved in a minimum

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

• enables the highly regioselective formation of meta-acylated ketone products 16 through a radical pathway. The NHC-catalyzed novel acylation was achieved using acyl fluorides 4 and electron-rich arenes 15 in the presence of NHC (20 mol %), photocatalyst (5 mol %), and Cs2CO3 in CH3CN at room temperature

Synthesis and characterization of a isothiouronium-calix[4]arene derivative: self-assembly and anticancer activity

• Giuseppe Granata,
• Loredana Ferreri,
• Claudia Giovanna Leotta,
• Giovanni Mario Pitari and
• Grazia Maria Letizia Consoli

Beilstein J. Org. Chem. 2025, 21, 2535–2541, doi:10.3762/bjoc.21.195

• Instrument, Malvern, UK) equipped with a 633 nm laser, at a scattering angle of 90° and 25 °C temperature. The size of the particles was calculated from the diffusion coefficient using the Stokes–Einstein equation: where D is the diffusion coefficient, k is the Boltzmann constant, T is the absolute

• temperature, η is the solvent viscosity, and R is the solute radius. The zeta potential (Z) was calculated by using Henry’s equation where UE is the electrophoretic mobility, ζ is the dielectric constant, f(Ka) is the Henry’s function, and η is the viscosity. Biological assays: Cell viability was measured by

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

• pentacyclic ring system. A general downfield shifting of the entire set of signals by no less than 0.5 ppm supports the expansion of the overall aromatic π-system upon annulation. Aromatic signal symmetry for non-annulated compounds 12 and 42 show a lack of distinct rotational isomers at room temperature on

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

• selectivity for each of the remaining three mismatched base pair combinations. Binding studies were then performed by annealing each of the PNA strands (PNA1–PNA3) with the four RNA hairpins (HRP1–HRP4). UV thermal melting studies reveal an inflection point at the temperature where the PNA dissociates from

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

• formation of liquid-ordered (Lo) domains [16]. To further assess the effect of membrane rigidity on rotaxane behavior, we also studied LUVs composed solely of DPPC lipids, which form a highly ordered gel phase (Lβ) at room temperature due to their saturated acyl chains [17]. Rotaxane 1 was incorporated into

• ). Similarly, in LUVs composed of pure DPPC, which adopts a highly ordered gel phase (Lβ) at room temperature [17], minimal release was observed: 7% with rotaxane 1-E, 3% with rotaxane 1-Z, 6% with rotaxane 2, and 4% with axle 3 (Table 1, Figure 4a, and Supporting Information File 1, Figures S1d and S10). Our

• rotaxane 1 [15]. We examined whether dye release in DPPC LUVs could be enhanced by increasing the temperature above the lipid’s phase transition temperature (Tm = 41 °C) (Supporting Information File 1, S2.4). Below Tm, DPPC is in the gel phase (Lβ), where the hydrocarbon chains are highly ordered, forming

Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• 3) was used as solvent, the reduction of disulfide 3 with NaBH4 proceeded more efficiently at reflux for 2 h. The reaction mixture was then treated with K2CO3 and the alkylating agent at room temperature. The product was identified as the desired 3-benzylthio-substituted thiophene-2,5-dicarboxylate

• reactions, probably involving ester hydrolysis or alkylating agent decomposition, can be avoided by omitting the external base. In addition, Na2S2O4 was investigated as a reductant in a DMF/water 9:1 (v/v) mixture at room temperature (Table 2, entry 6). In the presence of both K2CO3 and the alkylating agent

• also gave product 7a in about 25% yield, along with the formation of a mixture of byproducts. It was found that the most favorable conditions for cyclization of compounds 4a, 4b, and 5a were their treatment with excess LiH in a solution of dry DMF at room temperature for 24 h. In this way, products 7a

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• failed to enhance the product 2a yield (Table 1, entry 10). Attempts to optimize the reaction temperature did not yield improvements either (Table 1, entry 11). Control experiments confirmed that both the palladium catalyst and AgNO3 are essential for the reaction to proceed, as omission of either

• NiCl2/NaBH4 in methanol at room temperature, affording the corresponding amine 4 in 93% yield. To align with green chemistry principles, we employed a recently reported mechanochemical protocol by Ito and co-workers for the reduction of nitro compounds to amines [72]. Using this solvent-free method

• , 1.2 equiv). Then, the solvent 1,4-dioxane (2.0 mL) was added, and the reaction mixture was allowed to stir in a preheated oil bath at 120 °C for 24 h. Upon completion of the reaction time, the reaction mixture was cooled to room temperature and diluted with dichloromethane (10 mL). The reaction