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

• stoichiometric protonation to afford the hydrogenation product, highlighting the limitations of directly extending the hydride-free ET/PT manifold to C=O bond reduction. In 2024, the Anderson group reported an electrocatalytic semihydrogenation of alkynes [122] enabled by ligand-based storage and delivery of an

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

• lower hydrogenation yields for 7b and 7c presumably stem from labile hydrogens in the substituents that promote N–O bond cleavage under hydrogenation conditions, leading to the corresponding amines [37]. It should be noted, however, that this proposed pathway remains speculative and requires further

• spectrum of the nitroxide 9a (TEEPONE) was identical to that reported in the literature [21], and the IR spectrum of 9d was similar, with a strong absorption band at 1716 cm−1, characteristic of the carbonyl (C=O) stretching vibrations. The 1H NMR spectra of the reduced derivatives of 9a,d showed no

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

• proceeds at the C–H bond on the quinoline adjacent to the amide group and at the amide N–H bond in the presence of 10 mol % Pd(OAc)2 in o-xylene as a solvent to afford the cyclized product in 34% yield. The yield increases to 81% when the reaction is carried out with 80 mol % P(4-MeOC6H4)3 as a ligand and

• preparation of annulation precursors through o-brominated aniline derivatives [36][37][38][39][40][41]. Furthermore, the reported methodologies for synthesizing N-heterocycle-fused lactams are characterized by either low efficiency or protracted processes [42][43]. On the other hand, benzocyclization

• catalyst (Table 1, entry 7). When the reaction temperature was reduced to 110 °C, 120 °C, or 130 °C, product 3aa was obtained in lower yields in all cases compared with entry 7 (Table 1, entries 8–10). Using o-xylene as the solvent gave results similar to those obtained with DMF (Table 1, entry 11

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

• Timur O. Zanakhov Ekaterina E. Galenko Mikhail S. Novikov Alexander F. Khlebnikov Saint Petersburg State University, Institute of Chemistry, 7/9 Universitetskaya Naberezhnaya, St. Petersburg 199034, Russia 10.3762/bjoc.22.70 Abstract The Cs2CO3-induced condensation of 2-(diazoacetyl)-2H-azirines

• starting diazoketone 1a–i and l, while under the conditions used it was not possible to achieve complete conversion of diazoketones 1j,k and the yield of compounds 5n,o was 18 and 23%, respectively. The first step of the reaction fails with aliphatic aldehyde (propanal) and the weakly electrophilic N

Diastereodivergent electrophilic trapping of α-boryl lithium derivatives

• Tereza Pavlíčková,
• Noam Orbach and
• Ilan Marek

Beilstein J. Org. Chem. 2026, 22, 882–887, doi:10.3762/bjoc.22.68

• engaging in diverse bond-forming processes, including C–C, C–O and C–N bond formations [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Despite their growing utility, controlling the stereoselectivity in substitution reactions of α-boryl carbanions remains a formidable

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

• thiophosphorodichloridate reagents 25, as shown with hexahistidine-tagged proteins (Scheme 9d) [94]. Aspartate and glutamate, while weakly nucleophilic, can undergo O-alkylation via diazo compounds 26 (Scheme 9e) [95][96]. Arginine, traditionally difficult to modify due to its high pKa values, can be targeted with

• nearby target residue such as histidine (Scheme 11a) [105], aspartate (Scheme 11b) [106] and lysine (Scheme 11c) [107]. For example, reagents containing o-hydroxybenzaldehyde (31, 32) and β-nitroalkene (33) can reversibly engage lysine and cysteine residues, respectively, while a proximal electrophile

• bioconjugation chemistry [111][112][113], manipulating the composition of native protein glycans, known as glycoengineering, has become a privileged strategy for site-specific modification without altering the protein’s native amino-acid sequence. This approach requires the target protein to be N- or O

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

• trialkylphosphines, anionic carbon and hydride ligands. N- and O-lone pair donors (pyridine, water) are weak ligands. The following indicative series is typical for Pt(II), although there may be slight variations in the specific ordering depending on the complex type under investigation: CO, CN−, C2H4 > P(alkyl)3

• into gold hydrides by stepwise O-transfer reactions to phosphine (Scheme 6) [55]. Quite a different mechanism for the conversion of Au–OH into Au–H was found by Goldberg and co-workers for the hydrogenolysis of [(P^C^P)AuOH]+, which requires an acid catalyst [56]. A mechanistically similar heterolytic

• proved not possible due to the trans-influence of the N donor, which renders (C^N^C)AuH stable to hydrolysis (Scheme 8) [30]. A by-product of this cycle is the gold(III)–CO2 complex 14, also obtainable from [(C^N^C)Au]2O by insertion of CO into the Au–O bond. More recently, Nevado et al. isolated a

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

• -withdrawing nature of the S=O group. The second redox stage characterizes the transformation of the sulfoxide fragment and is observed in most cases at 1.82–1.91 V. The radical-scavenging activity and antioxidant properties of the unsymmetrical sulfoxides and their precursor thioethers were evaluated using

• ]. However, despite significant progress in the study of catechols with sulfide linkers, the chemistry of sulfoxides and sulfones is still a relatively unexplored area. Polyfunctional catechol thioethers are most commonly synthesized via the Michael reaction between o- or p-benzoquinone and the corresponding

• presence of the readily oxidizable catechol core. The presence of a redox-active catechol moiety adjacent to the sulfoxide group can significantly influence the formation of intra- and intermolecular hydrogen bonds and affect the O–H bond dissociation energy, which in turn may substantially impact the

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

• % yield) followed by treatment with 9-fluorenylmethyloxycarbonyl chloride to install the Fmoc group in 97% yield. The galacturonic acid precursor 3 was prepared from thioglycoside 11. Global deacetylation followed by the introduction of a 4,6-O-silylidene group afforded diol 12 (88% over two steps

• furnished tetrasaccharide 15. Subsequently, donor 3 was coupled with compound 15 under NIS/TfOH promotion to yield pentasaccharide 16 in 89% yield. The stereoselective construction of the 1,2-cis linkage was directed by the bulky 4,6-O-silylidene protecting group of 3. Treatment with HF·pyridine

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

• halogenated azobenzene acrylate monomers bearing fluorine, chlorine or bromine substituents is reported. The monomers were prepared via a facile three-step synthetic route involving azo-coupling, O-alkylation and O-acylation. Apart from the steady electrochemical properties, halogen substitution proved to be

• salts prepared in situ from the commercially available aromatic amines 2a–f [25]. The reaction was buffered by a 10% aq solution of sodium hydroxide and afforded the azobenzenes 3a–f with yields ranging from 41 to 93%. These intermediates were further O-alkylated using 6-chlorohexanol in the presence of

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

• , selonsertib, Z8, Z30, or the combination of GW4064 and selonsertib for 2 h prior to OA stimulation (600 μM). (A) Representative Oil Red O staining images (40×). (B) Quantification of staining intensity by ImageJ. Data are presented as mean ± SD (n = 3). Statistical significance was analyzed by one-way ANOVA

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

• ]. There are clearly some subtle interactions that contribute to the observed energy differences between the differently shaped two transition states, but undoubtedly their aggregation leads to a significant overall energy difference. Although one of the aryl rings is close to eclipsing one of the S–O

• methanesulfinate or p-toluenesulfinate and 1 equivalent of Rongalite (50 °C, AcOH/H2O, o/n) led to a mixture of products. These results are tabulated in Table 1. Mixtures of cyclic and acyclic products were obtained in both cases. Our initial interpretation was that the ratios reflected the relative rates of

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

• constraints and π–π interactions occurring in transition state E between the aromatic rings of the enone and iminoester substrates. It has been also demonstrated that in this particular (3 + 2) cycloaddition reaction ligand L9 acts as a pseudo-bidentate ligand. The formation of the enone Cu−O bond and the

• of a five-membered N,O-bidentate metalated azomethine. At the same time, a suitable coordinating nitrogen-containing heterocycle, such as a 2-pyridyl group, can also provide sufficient activation via the formation of an N,N-bidentate metalated azomethine, which facilitates asymmetric cycloaddition

• due to the possibility of cycloaddition at the carbon–oxygen double bond (C=O) of the aldehyde, which acts as an alternative to the carbon–carbon double bond (C=C) [83]. In 2016, Sridharan reported a one-pot iridium-catalyzed three-component dehydrogenation/1,3-dipolar cycloaddition cascade reaction

Photoorganocatalytic trifluoromethylation of (het)arenes in green conditions

• Egor N. Boronin,
• Svetlana E. Kaurkina,
• Milena M. Svetlakova,
• Anton S. Bolshakov,
• Maxim V. Arsenyev,
• Vasilii F. Otvagin,
• Alexey Yu. Fedorov,
• Timothy Noël and
• Alexander V. Nyuchev

Beilstein J. Org. Chem. 2026, 22, 662–671, doi:10.3762/bjoc.22.50

• , including rhodamine B, rhodamine 6G, eosin Y, riboflavin, methylene blue, THPP (tetrahydroxyphenylporphyrin), Birch O-PC™ C0103 (benzo[ghi]perylene monoimide) [28], 4CzTPN (tetracarbozalylterephthalonitrile), and 4CzIPN (tetracarbozalylisophthalonitrile), did not afford the desired product (Table 2, entry 1

• ); unreactive substrates are shown in Supporting Information File 1, Schemes S4 and S5. Benzene, toluene, tert-butylbenzene, biphenyl, naphthalene, o-xylene, and durene afforded the corresponding products 2–8 in moderate yields. In contrast, mesitylene, a less electron-enriched substrate than durene, gave

Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• )] (1a) with formic acid provides the formato species [Cu{OC(O)H}(IPr)] (1b) [52][53]. It was hypothesized that the thermal decarboxylation of 1b would generate in situ a highly reactive hydride species. The reaction of the latter with formic acid would regenerate the formato complex and release H2

Towards the targeted protein degradation of CK2: design and synthesis of CAM4066-based PROTACs

• Sophie Day-Riley,
• Sona Krajcovicova,
• Aryaman Raj Sokhal,
• Jan L. Venne,
• Paul Brear,
• Marko Hyvönen,
• Benjamin C. Whitehurst,
• Jason S. Carroll and
• David R. Spring

Beilstein J. Org. Chem. 2026, 22, 611–619, doi:10.3762/bjoc.22.47

• = dimethylformamide; HATU = O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate; THPTA = tris(3-hydroxypropyltriazolylmethyl)amine; TFA = trifluoroacetic acid; VHL = von Hippel–Lindau. Supporting Information Supporting Information File 14: Experimental part and copies of NMR spectra

Regioselective approach to 5-arylsulfonylisoxazoles and their antimicrobial activity

• Artem S. Sazonov,
• Dmitry A. Vasilenko,
• Denis V. Porfiriev,
• Yuri K. Grishin,
• Rimma A. Gazzaeva,
• Alisa P. Chernyshova,
• Maxim A. Kryakvin,
• Anna A. Baranova,
• Vera A. Alferova and
• Elena B. Averina

Beilstein J. Org. Chem. 2026, 22, 592–602, doi:10.3762/bjoc.22.45

• -sulfonylisoxazoles based on nucleophilic aromatic substitution of the nitro group in 3-EWG-5-nitroisoxazoles by treatment with thiophenols as S-nucleophiles and subsequent oxidation of the thioaryl group (Scheme 1, approach D). Previously, we reported that 3-EWG-5-nitroisoxazoles readily react with various N,O,S

Continuous-flow carbonyl hydrogenation under subatmospheric to atmospheric hydrogen pressure enabled by robust heterogeneous Pt–Fe catalysts

• Hiroyuki Miyamura,
• Ryosuke Kajiyama,
• Shun-ya Onozawa,
• Yoshihiro Kon and
• Shū Kobayashi

Beilstein J. Org. Chem. 2026, 22, 575–582, doi:10.3762/bjoc.22.43

• bimetallic nanoparticles, Al2O3 was added to the mixture, followed by methanol. The resulting solid catalyst was collected by filtration, washed with solvents, and heated twice. Si‒Si bonds in DMPSi were partially oxidized to form Si‒O‒Si bonds during the preparation process, and they became cross-linked to

Experimental and DFT studies on the regioselective methanolysis of 5-azido-9-oxabicyclo[6.1.0]nonan-4-yl 4-nitrobenzoate isomers

• İlknur Polat,
• Selçuk Eşsiz and
• Emine Salamci

Beilstein J. Org. Chem. 2026, 22, 547–556, doi:10.3762/bjoc.22.40

• , pharmaceutical compounds, and chiral ligands. The Lewis acid-catalyzed ring-opening reaction of cyclohexene oxide by MeZH (Z = O, S, and NH) is well known [20]. However, studies on large-sized bicyclic epoxides remain relatively limited in the published literature. In our previous study, we performed the ring

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

• ketophosphonate 169 using MePO(OMe)2 and n-BuLi. Notably, building block 171 used herein can be synthesized from 170 within 6 steps including a kinetic resolution with Amano lipase PS-800. [94] Another fragment, 181, was synthesized from alcohols 173 and 174, which were perpared from tri-O-acetyl-ᴅ-glucal and (S

• . Reductive N–O bond cleavage and stereospecific reduction with Me4NBH(OAc)3 yielded diol 198, whose primary alcohol unit was PMB-protected, while the secondary one was methylated. Dihydroxylation and protection with 2,2-dimethoxypropane yielded 199. Then, desilylation with TBAF and DMP-oxidation led to

• ; (m) TBDMSCl, imidazole, DCM, 50 °C; (n) DIBAL-H, toluene, −78 °C; (o) 36, n-BuLi, −78 to −50 °C; (p) i. DMP, DCM, rt; ii. SmI2, MeOH, THF, −78 to −50 °C; 18-crown-6: 1,4,7,10,13,16-hexaoxacyclooctadecane, 9-BBN: 9-borabicyclo[3.3.1]nonane, (±)-CSA: camphorsulfonic acid. Synthesis of 79. Above

Synthesis and uranyl(VI) extraction performance of a calix[4]pyrrole–tetrahydroxamic acid receptor

• Sara Karnib,
• Rana Baydoun,
• Wissam Zaidan,
• Nancy AlHaddad,
• Omar El Samad,
• Bilal Nsouli,
• Francine Cazier-Dennin and
• Pierre-Edouard Danjou

Beilstein J. Org. Chem. 2026, 22, 486–494, doi:10.3762/bjoc.22.36

• mixture of acetonitrile and acetone. Using this protocol, the PCP α,α,α,α-isomer was recovered in 47% yield, as previously reported by Namor and Shehab [49]. Subsequently, the synthesis of the PCP ester derivative (PCP E) was carried out via O-alkylation of PCP with ethyl bromoacetate in dry acetone/K2CO3

• by the disappearance of the characteristic signals of the ethyl group and an upfield shift of 0.27 ppm for the O–CH2 protons compared to the spectrum of the PCP ester. However, signals corresponding to DBU at 1.5, 2.3, and 3.1 ppm were still observed (Supporting Information File 1, Figure S7) despite

• %). The structure of PCP HA was fully characterized by 1H NMR and 13C NMR (DMSO-d6) as well as by HRMS (ESI+) (Figures S3–S6, and S9 in Supporting Information File 1). In the 1H NMR spectrum, two sets of singlets at 4.41 and 4.76 ppm (CH2) were attributed to the –O=C–CH2–O– groups of the E/Z isomers of

Recent advances in the stereoselective synthesis of distal biaxially chiral molecules

• Fanxing Zhou,
• Chen Zhang,
• Lingyu Sun,
• Yiyun Fang,
• Siming Zheng,
• Lina Hu,
• Mengyang Shen,
• Zhen Zhao,
• Wei Xu,
• Yunqiang Sun and
• Zi-Qiang Rong

Beilstein J. Org. Chem. 2026, 22, 461–479, doi:10.3762/bjoc.22.34

• [2 + 2 + 2] cycloaddition reaction between α,ω-diynes 1 and monoalkynes 2, providing an alternative to traditional asymmetric coupling strategies for the synthesis of C2-symmetric biaryl chiral compounds (Scheme 1a) [40]. They further demonstrated the feasibility of constructing N-, O-, and C

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

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

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

• ][3][4][5][6][7][8][9][10], we previously synthesized hetera[7]orthocyclophenes 1 having a heteroatom-embedded ansa-chain (X = O or NR) and an (E)-alkene moiety (Figure 1) [6][9], and found that the orthocyclophenes exhibit dynamic planar chirality in a wide range of stereochemical stability depending

• on the differences of the heteroatom and substituents on the (E)-alkene moiety [11][12]. The half-lives of the optical activity optt1/2 of 1aa (X = O, Y = H) and 1ba (X = NTs, Y = H) were 380 h and 56.7 h at 25 °C, respectively, indicating that the stereochemical stability of the oxygen-containing

• -substituted oxacyclophenes 1ab (X = O, Y = Me), 1ac (X = O, Y = Ph), and 1ad (X = O, Y = I), in which 1ad was used as the key intermediate for the synthesis of 1ab and 1ac via Kumada–Tamao coupling with Grignard reagents (Figure 2). Results and Discussion Retrosynthesis and synthesis of the C6-iodo

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

• ···C distance of 3.588 Å. Third and fourth, as shown in Supporting Information File 1, Figure S20, the intermolecular interaction of C–H···O, having an H···O distance of 2.544 Å and the (π···π) interaction having a C···C distance of 3.376 Å, stabilise and glue the self-assembled architecture in the

• selenium center. The second important feature is the torsional motion in the propylene linker attached to the imide nitrogen of the naphthalimide core. The calculated O–C–C–C torsional angle from the gas-phase structure of 7 is −61.5°. The observed torsional angle from the solid-state structure of 7 is

• −69.7°. This shows good agreement between the solid-state and gas-phase geometries of 7. In contrast, although a solid-state structure is not available, the computed O–C–C–C torsional angle from the gas-phase geometry of 8 is 179.7°. The comparison of the computed torsional angles between the two

Cone p-aminocalix[4]arenes enriched with ‘clickable’ alkyne or azide functionalities

• Ilia Korniltsev,
• Vasily Bazhenov,
• Alexander Gorbunov,
• Dmitry Cheshkov,
• Stanislav Bezzubov,
• Vladimir Kovalev and
• Ivan Vatsouro

Beilstein J. Org. Chem. 2026, 22, 399–415, doi:10.3762/bjoc.22.28

• conformational interconversions), thereby favoring or disfavoring the C4v-symmetric ‘ideal’ cone conformation of the calixarene core required for capsule formation [59]. To check this, 1H NMR spectra from the CDCl3 solutions of multifunctionalized calixarenes 47–51 and their 1:1 mixtures with the known O