Rhodopyran, a carboxylated hexahydrocyclopenta[b]pyran from Rhodococcus

• Enjuro Harunari,
• Sara Fushimi and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2026, 22, 1107–1113, doi:10.3762/bjoc.22.89

• concentrate was fractionated by silica gel column chromatography, and preparative HPLC afforded rhodopyran (1, 22.7 mg from 2 L of culture, corresponding to 0.18% of the 1-BuOH extract). An uninoculated A-3M medium control was incubated for 5 days and processed under identical conditions. HPLC analysis showed

• no peak corresponding to rhodopyran (1) at the retention time of 1 in the medium control (Figure S9, Supporting Information File 1), indicating that 1 was not a pre-existing medium component detectable under the present HPLC conditions. Although several additional UV-detectable peaks were observed in

• the culture extract, they were either also present in the medium control, present only in trace amounts, or did not yield sufficient material for complete structure elucidation. Therefore, this study focused on compound 1. Compound 1 was obtained as an optically active colorless powder ([α]D25 −69 (c

Controlled supramolecular assemblies of luminescent tridentate cyclometalated alkynylgold(III) amphiphiles in aqueous media

• Kelvin Sze-Yim Cai,
• Brian Boyan Liu and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2026, 22, 1097–1106, doi:10.3762/bjoc.22.88

• tridentate cyclometalated gold(III) amphiphile (GA) with flexible molecular structure modifications. Counterion exchange with sodium tosylate induces notable luminescent enhancement and enables control over supramolecular assembly processes. This approach drives a supramolecular assembly transformation of GA

• line), which was reversed upon cooling to 20.0 °C. This thermal annealing process is fully reversible with clear isosbestic points, suggesting that the supramolecular assembly of GA in aqueous media is under thermodynamic control without observable degradation. A methanol solution of GA (200 µM) shows

Synthesis and acaricidal activity against Varroa destructor of α- and γ-costic acid dimers

• Alessandro Santarsiere,
• Ernesto Santoro,
• Maria Letizia Ciavatta,
• Marianna Carbone,
• Sonia Ganassi,
• Cosimo Tedino,
• Antonio De Cristofaro,
• Antonio Evidente and
• Stefano Superchi

Beilstein J. Org. Chem. 2026, 22, 1088–1096, doi:10.3762/bjoc.22.87

• %, thus emerging as the most promising candidate for the development of effective and environmentally friendly strategies for the control of V. destructor. Furthermore, it may hold potential for the biocontrol of other mite pests affecting economically important crops such as legumes and cereals, which

• ,γ-costic acid heterodimer esters in comparison with their parent monomeric acids. Results and Discussion Given the significant economic and ecological impact of V. destructor, considerable efforts have been devoted to the development of acaricides to control this ectoparasite [21]. However, the use

• control strategies based on natural compounds. To date, both α-costic acid (1) [14] and β-costic acid (2) [18] have shown promising results against V. destructor, whereas no studies have reported the acaricidal properties of γ-costic acid (3). Therefore, we deemed it worthwhile to investigate the

Amino acid-based surfactants: sustainable synthesis and antimicrobial mechanisms

• Rafaela Gomes Bezerra,
• Lourdes Pérez and
• Francisco Fábio Oliveira de Sousa

Beilstein J. Org. Chem. 2026, 22, 1067–1085, doi:10.3762/bjoc.22.85

• reactions. N-Alkylation is mainly achieved either by reductive amination with long-chain aldehydes followed by chemical reduction, or by direct nucleophilic substitution using activated alkyl halides or sulfonates [6][10][13]. Reductive amination generally affords improved control over mono-N-alkylation and

• moderate to high yields, whereas direct alkylation requires strict stoichiometric and reaction control to minimize overalkylation and side reactions [13]. In addition, double-chain derivatives (e.g., LANHCn) are commonly obtained via aminolysis of methyl esters with long-chain amines under thermal

• bromide (DDAB), one of the most widely studied double-chain cationic surfactants due to its strong antimicrobial and biofilm-control activity [42][43]. However, DDAB lacks the biodegradability and biocompatibility typically associated with amino acid-derived surfactants and, similarly to other

Synthesis of functionalized, 13-alkyl-substituted coralyne derivatives and investigation of their interactions with duplex and abasic site-containing DNA

• Laurin Beckmann,
• Jason Lennard Kunze,
• Hannah Karola Strunk,
• Maurice Michel and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 1057–1066, doi:10.3762/bjoc.22.84

• -functionalized coralyne derivative 2g binds to AP site-containing DNA, as the observed effect is characteristic of AP–DNA ligands. Moreover, this result is in agreement with the control experiment that demonstrated the general ability of compound 2g to form oxime ethers with aldehydes (Scheme 4). As a result

• -functionalized linker, that is well known to bind to the ribose residues in abasic sites of damaged DNA [37][38][58]. In first control experiments, it was demonstrated that, indeed, the alkoxyamine can be released readily from a Boc-protected precursor and directly intercepted by reaction with an aldehyde

One-pot four-component sequential synthesis of S-alkyl dithiocarbamates using lipase as a biocatalyst

• Mansour Shahedi,
• Pargol Tahmasebi pour and
• Zohreh Habibi

Beilstein J. Org. Chem. 2026, 22, 1048–1056, doi:10.3762/bjoc.22.83

• , in previously reported lipase-catalyzed promiscuous reactions, significant stereochemical induction has generally not been observed or discussed [36][37][38]. To investigate the reaction mechanism and the catalytic role of the enzyme in enhancing the efficiency of the second step, control reactions

• reaction efficiency when compared to the optimized method (Scheme 5b). Based on the control reactions and previous studies a mechanism is proposed (Scheme 6). The reaction begins with a nucleophilic attack by the activated ketoester, facilitated by the triad amino acids of lipase, on the carbonyl group of

• ), Novozyme 435 (30 mg), aniline (0.05 mmol), CH3CN (1 mL), 30 °C, 12 h; then, CS2 (4, 0.4 mmol), amine 5c,d (0.2 mmol), 25 °C, 12 h. Control reactions. Proposed mechanism. Optimization of model reaction.a Supporting Information Supporting Information File 8: Product characterization data and copies of NMR

Synthesis of novel 1,2,4-oxadiazole-isoxazoline hybrids and their in silico potential with adenosine receptors

• Pshtiwan S. Mohammed,
• Mohammed K. S. Dalo,
• Onur C. Yazıcı,
• Muhammet Yildirim and
• Akın Sağırlı

Beilstein J. Org. Chem. 2026, 22, 1033–1047, doi:10.3762/bjoc.22.82

• optimal reaction conditions. A series of experiments was carried out by varying the equivalents of 2e (1.2–1.5 equiv), 6d (1.0–1.5 equiv), sodium hypochlorite (1.6–20 equiv), and triethylamine (1.2–2.4 equiv) (Table 2). In addition, control reactions employing either triethylamine or sodium hypochlorite

• -oxadiazole-isoxazoline derivatives may serve as promising scaffolds for adenosine A₁ receptor modulation, with potential relevance to therapeutic applications such as cardiovascular regulation (e.g., heart rate control and contractility modulation) and central nervous system effects via neurotransmitter

Semisynthesis, characterisation, and antibacterial evaluation of a novel lecanoric acid-derived amide library

• Ethan D. Abbott,
• Sasha Hayes,
• Jonathan M. White,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 1023–1032, doi:10.3762/bjoc.22.81

• concentrations of DMSO in the assays was 1%. The negative control or untreated cultures consisted of inoculum and 1% DMSO. Antibiotic tobramycin (16 µg/mL) was used as a positive control. The initial OD600 and final OD600 were read before incubation at 37 °C and after 24 h incubation, respectively, followed by

Z-Selective semihydrogenation of alkynes via Ni/Lewis acid synergistic catalyzed system using DMF as hydrogen source and solvent

• Lei Kang,
• Haifeng Gao and
• Luo Yang

Beilstein J. Org. Chem. 2026, 22, 1004–1012, doi:10.3762/bjoc.22.79

• ). Notably, phosphine-ligated Ni complexes such as (dppe)NiCl2 showed poor activity (20% yield, Table 1, entry 6), while NiCO3·2Ni(OH)2·4H2O afforded 2a in 2% yield (entry 10). Unsurprisingly, control experiments confirmed that the reaction does not proceed in the absence of a nickel source (Table 1, entry

• to terminal alkenes. NiCl2/Zn(AcO)2·2H2O-co-catalyzed semihydrogenation of alkylarylacetylene and dialkylacetylene to (Z)-internal alkenes. See a) Figure S2 and b) Figure S3 in Supporting Information File 1. Control experiment using DMA as solvent together with exogenous formic acid instead of DMF

The role of spacer length and flexibility in peptide self-assembly

• Julian Link,
• Albin Lahu,
• Manfred Wagner,
• Tanja Weil and
• David Y. W. Ng

Beilstein J. Org. Chem. 2026, 22, 986–996, doi:10.3762/bjoc.22.77

• displayed fibrillar structures, however, their vertical distance was observed to be much lower (0.7–0.8 nm). In contrast, C0-Nap-ICA 8 showed no supramolecular structures (Supporting Information File 1, Figure S39). Control TEM experiments in Milli-Q-H2O (1% TFE) revealed fibrillar structures for peptides 6

• ) Bar plot showing the fluorescence intensity of Proteostat® at λem = 600 nm (λex = 550 nm) after incubation with C6-Nap-ICA 6, C3-Nap-ICA 7, or C0-Nap-ICA 8 (all 100 µM) in PBS (50 mM, pH 7.4, 1% TFE). Control shows the fluorescence of Proteostat® in PBS (50 mM, pH 7.4, 1% TFE). C) Violin plot

Electrochemical reduction of unsaturated carbon–carbon bonds via 3d transition-metal catalysis

• Geon Kang,
• Minki Jeon,
• Pooja Kumari Jat,
• Cheoljae Kim and
• Isaac Choi

Beilstein J. Org. Chem. 2026, 22, 955–981, doi:10.3762/bjoc.22.75

• unsaturated C–C bonds, enabling precise control without molecular hydrogen or stoichiometric reductants. This review summarizes recent advances in iron-, cobalt-, and nickel-catalyzed electroreduction of alkynes and alkenes, highlighting how electrochemical parameters and catalyst design unlock distinct

• reduction while circumventing the need for molecular hydrogen or stoichiometric reducing agents. Consequently, the merger of 3d transition-metal catalysis with electroorganic synthesis represents a conceptual shift beyond traditional reagent-driven approaches, enabling precise control over redox events

• as a convenient parameter for reaction control. In sharp contrast, constant potential electrolysis (CPE) enables selective activation of specific redox events by maintaining a defined electrode potential, thereby allowing precise control over electron transfer and minimizing undesired processes

Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• , including copper–amido-mediated nucleophilic addition or aminocupration, Lewis acid-type alkene activation, and radical-mediated pathways. These complementary mechanisms provide access to diverse alkene classes with control over regioselectivity (Markovnikov vs anti-Markovnikov addition), stereoselectivity

• regioselectivity (Markovnikov vs anti-Markovnikov addition), while stereochemical control (diastereo- and enantioselectivity) presents further challenges (Scheme 1) [7]. These challenges become more pronounced when using (hetero)aromatic amines as the N–H partners. Compared to aliphatic amines, aromatic amines and

• )aromatic N–H nucleophiles. Notably, ligand design has emerged as a powerful tool for tuning the reactivity and selectivity, including control over Markovnikov vs anti-Markovnikov addition and enantioselective induction in selected cases. These developments collectively underscore the unique adaptability of

Site-specific labelling of native peptides and proteins: chemical and enzymatic strategies

• Antonio Angelastro,
• Jonathan Bargh,
• Subhajit Guria,
• Victor Laserna and
• Louis Luk

Beilstein J. Org. Chem. 2026, 22, 857–881, doi:10.3762/bjoc.22.67

• (19) was later adapted for modification of an asparagine (Asn) residue in the Fc domain of trastuzumab [61]. Rhodium has also been used in visible-light-triggered single-electron transfer (SET) reactions, enabling labelling under mild conditions with spatiotemporal control. Another strategy employs a

• these options are unsuitable, other solvent-exposed nucleophilic residues (e.g., methionine, histidine, tryptophan, tyrosine or arginine) can be targeted, although such reagents are often prepared in-house and may lack positional control. When high-affinity ligands or binders are available, affinity

The trans-influence in gold chemistry from a catalytic perspective

• Manfred Bochmann

Beilstein J. Org. Chem. 2026, 22, 838–856, doi:10.3762/bjoc.22.66

• and reactivity in catalytic reactions [11][12][13][14][15][16][17][18][19]. There is however one important aspect of gold chemistry that is often under-appreciated: the strong control of reactions by the influence of a given ligand on another ligand in trans position, known as the trans-influence

• ]. However, there is apparently yet more versatility in the mechanisms of alkyne hydroauration and may operate for the [(P^N^C)AuH]+ cation 11. Nevado et al. found recently that 11 inserts both DMAD as well as terminal alkynes, to give Au(III) Z-vinyl complexes. Control experiments ruled out the involvement

Unsymmetrical sulfoxides with sterically hindered catechol fragment: synthesis, structure, electrochemical properties, and antiradical activity

• Daria A. Burmistrova,
• Vasiliy A. Fokin,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Maxim V. Arsenyev,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2026, 22, 828–837, doi:10.3762/bjoc.22.65

• states provides a powerful way to control organic molecules. Through the controlled conversion of thioethers to sulfoxides and sulfones [21], it is possible to tune their reactivity and biological properties. Indeed, compounds of this type possess pronounced neuroprotective properties [12][13][14

• establish a coherent framework for understanding the behavior of S-functionalized catechols. The ability to control the hydrogen-bonding propensity, redox potentials, and antioxidant activity by varying the substituent at sulfur and its oxidation level opens promising avenues for the design of biomimetic

Total synthesis of the capsular polysaccharide repeating unit towards the development of a glycoconjugate vaccine against Klebsiella pneumoniae ST512

• Shuo Zhang,
• Ondřej Daněk and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2026, 22, 821–827, doi:10.3762/bjoc.22.64

• . Keywords: glycoconjugate vaccines; glycosylation; oligosaccharides; selectivity control; total synthesis; Introduction The emergence and rapid spread of multidrug-resistant bacteria represent a critical threat to global health [1][2][3][4]. Among these pathogens, Klebsiella pneumoniae has surfaced as a

Synthesis and structural elucidation of a novel bis-spirooxindole from isatin and ethylenediamine

• Irene Moreno-Gutiérrez,
• Josefa L. López-Martínez,
• Sonia Berenguel-Gómez,
• Irene Torres-García,
• Duane Choquesillo-Lazarte,
• Manuel Muñoz-Dorado,
• Miriam Álvarez-Corral and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2026, 22, 813–820, doi:10.3762/bjoc.22.63

• , these results show that the reaction of isatin with ethylenediamine can be directed toward different structural outcomes depending on stoichiometry. Simple control of stoichiometry governs whether the system evolves through a conventional diimine pathway or diverges toward the assembly of a highly

Synthetic study of vic-bromination of diarylacetylenes, easy purification and separation

• Akane Togo,
• Hiyono Suzuki,
• Yuto Akai,
• Makoto Matsumoto,
• Yoshinori Suzuma,
• Hidehiko Kodama and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2026, 22, 795–802, doi:10.3762/bjoc.22.61

• , and solvent were examined (Table 1, entries 3–12). Because there was a possibility that a bromine radical was involved, TEMPO was used for the purpose of the ratio-control of E and Z isomers. TEMPO was found to have a tendency to suppress the generation of Z-2a in CH2Cl2 (Table 1, entries 6 and 8) [20

• make scale-up very easy. The E-selectivity was dropped in gram-scale synthesis, although the reason is unclear at present. For the understanding of the reaction mechanism, some control experiments were carried out. The reaction of 1a with NBS and n-Bu4NBr without FeBr3 gave trace amount of E-2a (Scheme

• . In addition, heptane played an important and critical role for purification and separation of the crude product. Scope and limitations for bromination of various diarylacetylenes together with the gram-scale synthesis and control experiments were also investigated. These results and findings can

Halogenated azobenzene acrylates: from efficient solution photoswitching to stable solid-state photochromic materials

• Martina Vachtlová,
• Michaela Fecková,
• Vítězslav Zima,
• Jan Podlesný,
• Milan Klikar,
• Oldřich Pytela,
• Patrik Pařík,
• Jakub Opršal,
• Eliška Juhaňáková,
• Veronika Chrtová and
• Filip Bureš

Beilstein J. Org. Chem. 2026, 22, 782–794, doi:10.3762/bjoc.22.60

• liquid crystalline copolymeric pendants in macromolecules capable to change their reflectance with the temperature. This feature potentially enables their usage in temperature sensing labels [22]. These representative applications clearly demonstrate a wide interest in a light-driven control over the

Design, synthesis, and biological evaluation of FXR/ASK1 dual-target modulators

• Xi Zhang,
• Jingyan Wang,
• Ziqiang Zhao,
• Caiyi Wang,
• Zenghui Ye,
• Wei-Yuan Ma,
• Jian-Xing Xu and
• Fengzhi Zhang

Beilstein J. Org. Chem. 2026, 22, 771–781, doi:10.3762/bjoc.22.59

• accumulation. The presence of lipid droplets was confirmed through direct visualization using Oil Red O staining (Figure 3A). The combined treatment with GW4064 and GS4997 exerted a stronger lipolytic effect than either positive control alone, and its activity was comparable to that of Z8. As anticipated, both

• -luciferase reporter assay in CHO cells cultured for 24 hours following addition of GW4064 and test compounds. Compared to the control group, **p < 0.01 and ns indicate no significant difference, with control; DMSO serving as the control group. ASK1 inhibition of all compounds. Results of the ADP-Glo™ kinase

• assay after treating ASK1 kinase with selonsertib and test compounds for 1 hour. Compared to the control group: **p < 0.01 and ns indicates no significant difference; control: DMSO control group. Effects of Z8 and Z30 on OA-induced lipid accumulation in HepG2 cells. Cells were treated with GW4064

Synthesis and biological evaluation of new brassinosteroid analogs with C-22 benzoate function

• María Núñez,
• Camila Escobar,
• Mario Párraga,
• Mauricio Soto,
• Luis Espinoza-Catalán,
• Katy Díaz and
• Andrés F. Olea

Beilstein J. Org. Chem. 2026, 22, 753–762, doi:10.3762/bjoc.22.57

• -carbonyl or 3β-hydroxy function in this ring. Additionally, the accumulation of the dephosphorylated form of the BES1 protein, which is part of the BRs signaling pathway and control their activity, has been evaluated as well. The results are analyzed in terms of BR analog’s structure and compared with

• –22 have been measured at different concentrations (Table S1, Supporting Information File 1). The activities, calculated as the difference of bending angles obtained for the analogs and the negative control, and normalized respect to the latter, are shown in Table 1. The data show that the plant

• response to exogenous application of brassinolide (1) (positive control) or synthetic BR analogs strongly depends on the chemical structure of the BRs. For example, the activity increases with increasing concentration of 1, and analogs 18, 20 and 22, whereas the opposite effect is obtained by applying

Rongalite addition to dienones: diastereoselectivity in cyclic sulfone synthesis; stereochemical rationalization and prospects as a general conjugate nucleophile

• Melina Goga,
• Hao Zong,
• James Franco,
• Jazmine Prana,
• Rudolph Michel,
• Antonia Muro,
• Elana Rubin,
• Janet Brenya,
• Henk Eshuis and
• Magnus W. P. Bebbington

Beilstein J. Org. Chem. 2026, 22, 742–752, doi:10.3762/bjoc.22.56

• sulfide oxidation. In that early work, the stereochemical analysis was dependent on conformational analysis and comparison of coupling constants in the 1H NMR spectra. Experiments discussed in our inital report confirmed that the reaction proceeded under kinetic control [21]. Closer examination of the

• 20, in contrast to the successful reaction with phorone (21) to give 22 [43] (Scheme 4). As a control reaction, we conducted the addition of commercially available sodium p-toluenesulfinate to mesityl oxide under analogous conditions, which produced known sulfone 23 [44] in high yield. This

• selectivity for formation of 26 at room temperature suggests a profile that is more reflective of kinetic control, such that we can argue that 26 forms between 1 and 2 orders of magnitude more rapidly than cyclic products 1a and 1b, such that they are not detectable in the 1H NMR spectra. Further anecdotal

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

• chiral metal complexes of Ag(I), Cu(I/II), Zn(II), Ni(II) with ligands of the Segphos, Fesulfos, or Biphamphos type [12][13][14][15]. Such catalytic systems control the enantioselectivity of cycloaddition and allow the preparation of enantioenriched pyrrolidines containing several stereocenters in high

• reactions is due to charge and orbital control [1]. Continuing the study of 1,3-dipolar cycloaddition reactions of ninhydrin-based azomethine ylides with cyclopropene dipolarophiles, our research group examined the interaction of cyclopropenes with azomethine ylides from ninhydrin and acyclic amino acids

• of regio- and endo-stereoselective spiro- and dispiro-derivatives of azabicyclo[3.2.0]heptane 151 and 152 is due to orbital control along with second orbital interactions [101]. In 2015, Wu and co-workers described a multicomponent synthesis of various spiro[indole-pyrrolizine], spiro[indole

Anti-invasive and cytotoxic evaluation of a (+)-pinoresinol-based semisynthetic library against glioblastoma

• Chen Zhang,
• Kah Yean Lum,
• Jonathan M. White,
• Paul I. Forster,
• Nicholas Booth,
• Sunita A. Ramesh and
• Rohan A. Davis

Beilstein J. Org. Chem. 2026, 22, 691–704, doi:10.3762/bjoc.22.54

• ranging from 1.56−25 µM with a reduction of up to 65% invasion in comparison to the control [22]. Owing to the interesting biological activity of 2 and its moderate abundance in the seeds of E. maculata, we decided to generate five semisynthetic analogues 3−7 (Figure 2) and evaluate these compounds for in

• concentration of 1 µM with a treatment time of 5 h, and only (+)-4,4'-di(3,3-dimethylbutanoyl)pinoresinol (6) reduced the invasion of the cells (by ≈50%) when compared to the vehicle control. None of the other compounds tested reduced the invasive capability of the cells (Figure 7A). Based on the results of the

• to achieve a cell number of 15,000 cells per mL. Cells were seeded in a 96-well plate (Costar #3596) in triplicates at 100 µL/well (i.e., 1,500 cells/well) and incubated for 24 h at 37 °C and 5% CO2. Vehicle control (positive control) was the solvent DMSO, in which all compounds were dissolved, plus

Harnessing light energy with molecules

• Grace G. D. Han,
• Mogens Brøndsted Nielsen and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2026, 22, 680–682, doi:10.3762/bjoc.22.52

• larger systems or smart materials [9]. Photoswitches are, for example, relevant functional units for information storage or molecular electronic devices. They can serve to control ion transport, molecular assembly/disassembly, or the relative movement of units within molecular machines. In a Review