Intermolecular water attack to alkenylgold carbenes derived from 3-propargylindoles

• Lorena Renedo,
• Marta Solas,
• Samuel Suárez-Pantiga and
• Roberto Sanz

Beilstein J. Org. Chem. 2026, 22, 1221–1228, doi:10.3762/bjoc.22.98

• complexes as catalysts with lower catalyst loadings, while still providing similarly high yields of the expected alcohol 2b. Consequently, di-Ad-BrettPhosAuNTf2 (B) and Me4t-BuXPhosAuNTf2 (C), both bearing bulky ligands, were selected as the most active catalysts. In addition, the more readily available and

• corresponding dienylindole 7d and the alcohol 8d was obtained, allowing isolation of the hydroxylated indole in moderate yield as a single geometrical isomer. Surprisingly, the starting material was recovered upon using catalysts B or C with bulkier ligands, showing the unsuitability of these complexes for

• was subjected to the Au-catalyzed reaction in the presence of H2O. Under these conditions, the reaction led exclusively to the tetrahydropyrano[3,4-b]indole 9a, with no traces of diol 2x, the product expected from the intermolecular reaction with water (Scheme 6c). As anticipated, protection of the C2

An undecacyclic carbon-centered hydrocarbon radical: synthesis and investigation

• Ali S. Acan,
• Johannes Werner and
• Joachim Podlech

Beilstein J. Org. Chem. 2026, 22, 1196–1204, doi:10.3762/bjoc.22.95

• rings E’, C’, C, and E. The inner six-membered rings D’, B’, B, and D display a borderline behavior, as they are neither distinctly aromatic nor antiaromatic. This is likely a consequence of the antiaromatic indacene subunits embedded in the molecular framework (Scheme 4, highlighted in red) within the

• framework [36][37][62], particularly of the C’, B’, A fragment and its mirror image. In contrast, pronounced aromatic character is observed exclusively in the outer six-membered rings (F and F’), whereas the remainder of the framework predominantly shows antiaromatic character. The outmost rings are not

• be calculated and visualized with Herges’ ACID (anisotropy of the induced current density) method (Figure 8) [63][64]. The results suggest antiaromatic behavior for the five-membered rings. For rings B’, B, D’, and D, again a combination of aromatic and antiaromatic character is observed, which is in

Triazole-based hybrid molecules in anticancer drug discovery: structural classes and mechanistic insights, 2014–2025

• Meena Bhandari,
• Akshi Goyal and
• Deepak Yadav

Beilstein J. Org. Chem. 2026, 22, 1168–1195, doi:10.3762/bjoc.22.94

• ) analysis showed that compounds 20b, 20c, and 21b containing a triazole ring in 3- or 4-position of ring A and 2,3-dimethoxy groups on ring B, exhibited a strong activity against HepG2 cells, having a half-maximal inhibitory concentration (IC50) of 15.70 µM, 8.18 µM, and 4.26 µM, respectively. In contrast

• , compounds 21d with trimethoxy substitution on ring B generally lost cytotoxicity towards HuCCA-1, HepG2 and A549 cells. However, compound 21c reserved activity against HuCCA-1 with an IC50 of 6.13 µM. Compound 22 (Figure 7) 4-(1,2,3-triazol-1-yl)coumarin bearing a (4-fluorophenoxy)methyl substituent at the

• –coumarin hybrids tethered through a 1,2,3-triazole linker (24a,b and 25, Figure 7) showed promising cytotoxicity towards THP-1, COLO-205, and HCT-116 cancer cell lines with IC50 values ranging from 0.82 to 9.95 µM but displayed no significant effect on PC-3 cells. Importantly, the two-carbon spacer flanked

The surprising reaction of (chloro- and methanesulfonyloxy)(phenyl)methylphosphonates and –(phenyl)methylphosphine oxides with potassium diphenylphosphide followed by oxidation

• Zsuzsanna Szalai,
• Janka Bednárik,
• András Miskó,
• Angéla Takács,
• László Kőhidai,
• László Drahos and
• György Keglevich

Beilstein J. Org. Chem. 2026, 22, 1160–1167, doi:10.3762/bjoc.22.93

• . Beside the above approach marked as “method A”, products 8a–e completed with 8f could also be prepared by the direct phosphinylation of the starting (hydroxy(aryl)methyl)(diaryl)phosphine oxides 14a–f (Scheme 5, “method B”). The new products (14b, 16b–d, 15f, 8b–f) were fully characterized by 31P, 13C

• treatment. Multiple myeloma is a hematological malignancy characterized by the clonal proliferation of plasma cells, the terminally differentiated effector cells of the B-cell lineage within the bone marrow. Given the established role of phosphorus-containing drugs in the treatment of myeloma-related

• pathways (methods A and B) for the preparation of (diarylphosphinyl)(aryl)methyl diphenylphosphinates 8 starting from the corresponding (hydroxy(aryl)methyl)(diaryl)phosphine oxides 14. Unexpected route following the mesylation of (hydroxy(4-methoxyphenyl)methyl)(diphenyl)phosphine oxide (14f). Supporting

A cascade synthesis of 2-aminothiochromones from 2-fluorophenyl ketone and thiocarbonyldiimidazole

• Kai Zhang,
• Haofan Shao,
• Kangjun Liao,
• Ying Xu,
• Shimei Du,
• Yanfang Zhao,
• Gang Li,
• Wenzhen Xu,
• Haihong Huang and
• Peng Li

Beilstein J. Org. Chem. 2026, 22, 1151–1159, doi:10.3762/bjoc.22.92

• analogs of chromones [2], in which the oxygen atom is replaced by a sulfur atom, thiochromones are widely present in various natural products, functional materials, and biologically active molecules [3][4], such as MAO-B inhibitor [5], anticancer [6], antibacterial [7], and antimalarial compounds [8

• intermediate B, leading to the expulsion of the second imidazole molecule (B’). Notably, the key intermediate B was isolated from the reaction mixture, while intermediate A was characterized by mass spectrometry during the reaction. Collectively, these results indicate that the initial generation of a

Construction of CF₂ moieties in FDA-approved drugs (2016–2025): industrial routes, mechanisms, and scale-up considerations

• Wenyan Yao,
• Huanhuan Zhang,
• Xiaolong Yang and
• Feng Liu

Beilstein J. Org. Chem. 2026, 22, 1122–1150, doi:10.3762/bjoc.22.91

• -flow methods using SF4. 1.1.1 Glecaprevir and voxilaprevir (2017): As shown in Figure 2, compound 18 is the key alkyl–CF2 side chain for the synthesis of 1 and 2. There are four main methods for its construction: Route a [6] and route b [7] are based on fluorination of the terminal aldehyde group

• an inexpensive enzymatic process [8]), route a suffered from several scale-up issues: the use of OsO4 (highly toxic) and DAST (hazardous), the low fluorination yield, and a low overall yield of only 7% over ten steps. Route b [7] used compound 19, which contains an aldehyde group and a chiral carbon

• synthesis of the difluorocyclobutylamine side chain 38 in ivosidenib (3). Among them, route a (reported in 1987) [10] and route b (reported in 2005) [11] are both methods for constructing the four-membered ring. Routes c, d, and e use cyclobutane-containing starting materials and synthesize the target

Discovery of sugarnitriles A and B, and structural reassignment of SF-2140, from a sugarcane endophytic actinomycete Amycolatopsis sp. JS-O27

• Qiuyun Li,
• Ying Liu,
• Baoyue Wei,
• Yu Sun,
• Di Mao,
• Yanmin Zou and
• Shan Lu

Beilstein J. Org. Chem. 2026, 22, 1114–1121, doi:10.3762/bjoc.22.90

• (2) and B (3), were isolated from a sugarcane endophytic actinomycete Amycolatopsis sp. JS-O27. The planar structures of 1–3 were established by HRESIMS data and detailed 1D/2D NMR spectroscopic analysis, and the conformations of the sugar moieties were deduced by the analysis of 3JH-H coupling

• (2) and B (3), were isolated from a sugarcane endophytic actinomycete strain Amycolatopsis sp. JS-O27 (Figure 1). This paper describes their isolation, structure elucidation, and biological investigations. Results and Discussion HPLC analysis of the MeOH extract of rice culture of Amycolatopsis sp

• , Supporting Information File 1, and Figure 2b). The large coupling constant (J = 9.4 Hz) between H-1' and H-2' indicated both the indole and the 2'-OH to be in pseudo-equatorial positions. Furthermore, the small coupling constants between H-2' and H-3', and between H-3' and H-4'b, and NOESY correlations of H

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

• unusual carboxylated hexahydrocyclopenta[b]pyran and expands the known metabolite diversity of Rhodococcus, highlighting Rhodococcus as a source of uncommon natural-product scaffolds. Keywords: bicyclic compound; cyclopenta[b]pyran; natural products; Rhodococcus; specialized metabolites; Introduction

• than that of Streptomyces. In our continuing cultivation-based survey of metabolites from Rhodococcus, Rhodococcus sp. strain RD066637 was found to produce a new cyclopenta[b]pyran metabolite, rhodopyran (1) (Figure 1). Herein, we describe the isolation, structure elucidation, relative configuration

• , have been reported [16], whereas natural products featuring a cyclopenta[b]pyran skeleton are exceedingly rare [18][19][20][21][22][23]. Reported microbial natural products containing a cyclopenta[b]pyran motif include diospentenols A and B from Streptomyces sp. KMA-001, which possess a 7,7a-dihydro-2H

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

• Tapping mode. The sample solution (0.2 wt %, 5.0 μL) was dropped onto a freshly cleaved mica plate surface and spin-coated to remove excess solvent. (a) UV–vis absorption spectra of GA (200 μM) in MQ water heated to 50.0 °C (red line) and cooled to 20.0 °C (black line) at a rate of 1.0 °C/min. (b

• ) Emission spectra of GA (200 μM) in MQ water upon decreasing the temperature from 50.0 °C (black line) to 10.0 °C (purple line). (a) TEM image of a thermally annealed aqueous solution of GA (2.68 mM). (b) UV–vis absorption spectra and (c) emission spectra of GA (200 μM) in Milli-Q water at 20.0 °C after

• addition of sodium tosylate (1.0, 2.0, and 4.0 equiv). (a) Time-dependent UV–vis adsorption spectra of GA (200 μM) with addition of 1.0 equiv of sodium tosylate in Milli-Q water at 20.0 °C. (b) Time-dependent absorbance changes of GA at 420 nm with and without the addition of sodium tosylate (1, 2, or 4

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

• (right picture). Synthesis of costic acids derivatives. Reaction conditions: (a) ethylene glycol (0.5 equiv), pTsOH (0.1 equiv), toluene (2.0 mL/mmol), 100 °C, 4 h; (b) DMAP (0.1 equiv), DCC (1.4 equiv), CH2Cl2 (6.0 mL/mmol), ethylene glycol (1.0 equiv), 0 °C to rt, overnight; (c) DMAP (0.1 equiv), DCC

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

• related to their antimicrobial activity; b) To describe their possible mechanisms of action in the interaction with microorganisms; and c) To present the novel approaches and perspectives on the use of these innovative molecules. Materials and Methods The methodology for this integrative review was

• Figure 3. General structure and molecular properties of amino acid-derived surfactants Several molecular structures of the cationic amino acid-based surfactants are reported in the literature (Figure 4): (a) single chain surfactants with a single amino acid on the polar head and one alkyl chain, (b

• activity against fluconazole-resistant Candida spp. (MIC: 8–12 μg/mL) by disrupting mitochondrial function and inducing apoptosis, while also exhibiting synergistic effects with amphotericin B [19]. Similarly, glycine-based solutions (4.5%) have proven effective in eradicating Streptococcus spp. and

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

• )aminomethane) = 89.0 mM, c(B(OH)3) = 89.0 mM, c(Na2EDTA) = 1.0 mM, pH 8.0; I1/2 buffer: c(KH2HPO4) = 5.0 mM, c(NaCl) = 50.0 mM, pH 7.4. The ct DNA (approximately 2 mg/mL) was dissolved in BPE buffer and stored at 4 °C for at least 24 h. The solution was filtered through a membrane filter before use (pore size

• plate reader with λex = 485 nm and λfl = 535 nm was used. Structures of the representative DNA-binding protoberberine alkaloids 1a–c and coralyne (2a). Photometric (A) and fluorimetric (B) titration of ct DNA to 2e (c = 10 µM) (B) in BPE buffer (cNa+ = 16 mM, pH 7.0; with 10% v/v DMSO). Inset: plot of

• absorption (A) or emission (B) versus cDNA. CD (C) and LD (D) spectra of 2e (c = 10 µM) in the presence of ct DNA in BPE buffer (cNa+ = 16 mM, pH 7.0; with 10% v/v DMSO) at LDR = 0.0–2.0. Red: DNA in the absence of ligand, blue: LDR = 2.0. The arrows indicate the development of the bands during DNA titration

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

• . Reaction conditions: 1a–f (0.1 mmol), 2 (0.15 mmol), Novozyme 435 (30 mg), aniline (0.05 mmol), CH3CN (1 mL), 30 °C, 12 h; then, CS2 (4, 0.4 mmol), cyclic amine 5a,b (0.2 mmol), 25 °C, 12 h. Scope of the reaction with aldehydes and acyclic amines. Reaction conditions: 1a–c,e–g (0.1 mmol), 2 (0.15 mmol

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

• ) NH2OH·HCl, NaOH, EtOH–H2O (5:1), 50–55 °C, 30 min; b) NH2OH·HCl, EtOH, Et3N, 80 °C, 24 h; c) acryloyl chloride, CH2Cl2, rt; d) K2CO3, 1,4-dioxane, 120 °C, 24 h. Mechanism for the formation of novel 3,5-disubstituted 1,2,4-oxadiazolyl diarylisoxazolines 7a–ay (5-regioisomer). Precursor compounds (2a–k, 6a–j

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

• different time conditions: 1 h (reaction A), 2 h (reaction B), and 4 h (reaction C). The crude product from each reaction was pre-adsorbed to C8-bonded silica (≈1 g) and subsequently subjected to RP-HPLC using a semi-preparative C18-bonded silica Betasil column. Isocratic conditions of 10% MeOH (0.1% TFA

• dried down, and UV-active fractions were analysed by 1H NMR and UHPLC–MS, with compound 6 eluting at 34–35 min. Yields for the intended analogue 6 across the three reactions were 13% (reaction A, 1 h), 10% (reaction B, 2 h), and 6% (reaction C, 4 h), respectively. Due to the better yield of reaction A

• = 200.0 K, λ = 1.54184 Å, monoclinic, space group P21/c, a = 17.0659(2) Å, b = 7.45980(10) Å, c = 16.1534(2) Å, β = 117.493(2)°, V = 1824.22(5) Å3, Z = 4, Dc = 1.443 mg M−3, µ (Cu Kα) 1.981 mm−1, F(000) = 832, crystal size 0.33 × 0.27 × 0.06 mm3; 27980 reflections measured, θmax = 776.98°, 3842

Synthesis and optical resolution of 4,5-diaminohomoadamantane: a promising scaffold for chiral ligands and bioactive compounds

• Polina A. Man’kova,
• Vadim A. Shiryaev,
• Olga S. Podlipnova,
• Marat M. Khisyamov,
• Dmitry S. Nikerov,
• Alexander N. Reznikov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2026, 22, 1013–1022, doi:10.3762/bjoc.22.80

• , a few examples of homoadamantane derivatives showing pronounced biological activity are known. More than 40 homoadamantane polyprenylated acylphloroglucinols have been isolated from Hypericum plants [54][55][56]. Among them, hyperacmosins A and B showed a protective effect in paracetamol-induced

• ). The NaBH4/MoO3 system [81] led to the selective reduction of only the hydroxyimino group, affording azidoamine 7. The reduction of azidoxime 4 using LiAlH4 [75][87] allowed total reduction of both the oxyimino and azido groups, resulting in the formation of isomeric diamines 8a,b (Scheme 2). Since 4,5

• -diaminohomoadamantane was isolated as a mixture of trans- and cis-isomers 8a,b, we decided to synthesize trans-4,5-diaminohomoadamantane through ring opening of aziridine 9. This compound was obtained from homoadamantanone oxime by reduction with LiAlH4 [41]. Since the aziridine ring-opening reaction usually proceeds

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

• hydrogenation systems. HCOOH then reacts with the Ni species to form a formate nickel hydride intermediate B (HCOONi(II)H), a key species documented in nickel-catalyzed hydrogen-transfer reactions. Subsequent selective insertion of the internal alkyne into the Ni–H bond of B affords the vinyl-nickel

• 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

Rh(III)-catalyzed chelation-assisted C–H activation/annulation of 2-arylimidazolines with cyclic diazo-1,3-dicarbonyl compounds: a novel approach to tetracyclic annulated derivatives of 2,3-dihydroimidazo[2,1-a]isoquinoline

• Ivan Lyutin,
• Grigory Kantin,
• Olga Bakulina and
• Dmitry Dar'in

Beilstein J. Org. Chem. 2026, 22, 997–1003, doi:10.3762/bjoc.22.78

• intermediate B, followed by coordination of diazo compound 3 to give diazonium intermediate C. The latter transforms into a carbene complex D after nitrogen loss. The next intermediate E is a result of migratory insertion of the carbenoid into the C–Rh bond. The last step of the catalytic cycle is

• performed a reaction of substrate 2a with an equimolar amount of rhodium catalyst, which allowed isolation of compound 5 (intermediate B) in 35% yield (Figure 3b). Conclusion In conclusion, we have successfully extended the strategy of Rh(III)-catalyzed chelation-assisted C–H activation/annulation with

• biologically active compounds. a,b) Structure of biologically active 2,3-dihydroimidazo[2,1-a]isoquinolines (1) and their published syntheses. c) A novel approach to annulated 2,3-dihydroimidazo[2,1-a]isoquinolines via chelation-assisted C–H activation/annulation of 2-arylimidazolines proposed in this work. d

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

• achieve the desired solvent compositions. The exact volumes used are summarized in Supporting Information File 1, Table S1. A) Bar plot representing the assembly conversion of C6-Nap-ICA 6, C3-Nap-ICA 7, and C0-Nap-ICA 8 (all 100 µM) in PBS (50 mM, pH 7.4, 1% TFE) determined through analytical HPLC. B

• -ICA 7, or C0-Nap-ICA 8 (all 100 µM) in PBS (50 mM, pH 7.4, 1% TFE) with green fluorescence filter (λex = 470/40 nm, λem = 525/50 nm), scale bar = 40 µm. A) Scheme depicting the self-assembly propensities of C6-Nap-ICA 6, C3-Nap-ICA 7, and C0-Nap-ICA 8 in aqueous media. B) TEM micrograph of C0-Nap-ICA

• room temperature. The structures were stained with uranyl(IV) acetate (4%), scale bar = 0.5 µm. Created partly in BioRender. Lahu, A. (2026) https://BioRender.com/bvkpq0n. This content is not subject to CC BY 4.0. A) Fluorescence emission and B) absorbance of C6-Nap-ICA 6, C3-Nap-ICA 7, and C0-Nap-ICA

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

• the use of stoichiometric reagents. In this context, when electrochemistry is employed as a synthetic tool in organic chemistry, several critical parameters must be taken into account, including (a) electrode, (b) electrolysis mode, and (c) cell configuration (Figure 1). Among these, the choice of

Synthesis of sterically shielded piperidine nitroxides via acid-catalyzed heterocyclization of β-aminoketone derivatives with ketones

• Mark M. Gulman,
• Yurii I. Glazachev and
• Sergey A. Dobrynin

Beilstein J. Org. Chem. 2026, 22, 948–954, doi:10.3762/bjoc.22.74

• -tetrapropyl-substituted piperidine nitroxides, and sterically shielded nitroxides with functional groups in the side chain of the heterocycle. Results and Discussion Aminodioxolanes 4a,b were obtained from enones 1a,b via a modified literature sequence [30] involving phthalimide Michael addition, dioxolane

• formation, and hydrazinolysis (Scheme 1). The target 2-(2-aminoalkyl)-1,3-dioxolanes 4a,b were obtained in pure form after vacuum distillation. Conversion of α,β-unsaturated ketones 1a,b to aminodioxolanes 4a,b proceeded in 49% and 69% overall yield, respectively. In the 1H NMR spectrum of 4a

• ), the N-adjacent methine (2.71 ppm), and diastereotopic methylene protons (1.39, 1.58 ppm) supported the assigned structure. Compound 4b exhibited spectral data identical to those previously described [31]. The aminodioxolanes 4a,b were subjected to acid-catalyzed heterocyclization with the

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

• activated olefin, followed by aminocupration across the C=C bond to form the alkylcopper intermediate IV, which subsequently underwent proton transfer with aniline to furnish the β-amino product 1 while regenerating the copper–amido species II. Alternatively, path B proceeded through the direct nucleophilic

• or free ligands alone were ineffective, indicating that discrete copper–amido complexes served as catalytically active species, rather than merely functioning as Lewis acids. Although both pathways are mechanistically plausible, experimental evidence supports the nucleophilic addition pathway (path B

• that this key step could occur through either four- or six-membered cyclic transition states (III-a vs III-b), depending on the nature of the electron-withdrawing group on the olefin. Finally, proton transfer from the amine substrate released the hydroamination product and regenerated the active Cu

A practical CO₂-mediated synthesis of 5,6-carboxylated silicon-rhodamines for targeted probe development

• Dongjie Hou,
• Shaowei Wu,
• Ning Xu,
• Pengjun Bao,
• Wenhao Jia,
• Qinglong Qiao and
• Zhaochao Xu

Beilstein J. Org. Chem. 2026, 22, 915–924, doi:10.3762/bjoc.22.72

• -resolution imaging. Overall, this work improves the synthetic accessibility of functionalized SiR dyes and provides a concise and versatile platform for the rapid development of targeted super-resolution probes. (a) Modular structure of spirocyclic rhodamines. (b) Conventional carboxylation strategies. (c

• ) CO2-based direct carboxylation method developed in this work. (a) Direct carboxylation of brominated silicon-rhodamines 1a–c under n-BuLi/CO2. (b) Strategy for the one-pot functionalization of brominated silicon-rhodamines 1a–c to construct SiR–halo fluorescent probes 4a–c. (a–c) Conversion of three

• fusion protein, and mitochondria labeled with TOMM20-HaloTag fusion protein. (b) Average localization precisions of 4a and 4b for different organelles. (c) Long-term SMLM imaging of actin with 4b in live HeLa cells. (d) Schematic diagram of filopodia growth and wiggling process in (c). Scale bars: 5.0 μm

Palladium-catalyzed benzocyclization reactions of quinoline-2-carboxamides via sequential C–H/N–H functionalization

• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2026, 22, 905–914, doi:10.3762/bjoc.22.71

• efficient access to chemodivergent products. The developed reaction protocol is expected to be applicable to the synthesis of functional materials and bioactive molecules. Nuclear Overhauser effect (NOE) correlations in products (a) 3ab, (b) 3ac, (c) 3ad, (d) 3aj, and (e) 3ak. Various transition-metal

Cascade transformation of 2-(diazoacetyl)-2H-azirines to 2-aroyl-3-hydroxy-1H-pyrroles via condensation with aromatic aldehydes

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2026, 22, 897–904, doi:10.3762/bjoc.22.70

• ) exhibiting a lower relative Gibbs free energy than the starting compounds. According to the calculations, the reaction of azirine 1a and benzaldehyde 2c results in the formation of two diastereomers, (RR,SR)- and (RR,RR)-A, which can undergo a conformational transition to intermediates (RR,SR)- and (RR,RR)-B

• , which are capable of cyclization. The cyclization of (RR,SR)-B leads to the (1RR,3SR,6RR)-Pha-C isomer with the Ph group from benzaldehyde in the axial position, which readily transforms into the more stable (1RR,3SR,6RR)-Phe-C isomer with equatorial Ph group as a result of inversion of the 6-membered

• ring. The intermediate (RR,RR)-B immediately yields a more stable conformer with the Ph group from benzaldehyde in the equatorial position (1RR,3RR,6RR)-Phe-C, but the equilibrium as a whole is shifted towards the most stable isomer (1RR,3SR,6RR)-Phe-C isomer. According to the calculation, the