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

• complexes. Both terminal and internal alkynes could be inserted, with a wide variety of functional groups including alkyl, aryl, OH, COOH, amide and aldehyde substituents, but not DMAD. The excellent stereo- and regiochemical selectivity could be explained by a bimolecular mechanism, as confirmed by DFT

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

• the reaction with the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) and the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+•). In both assays, the lowest IC50 values among the studied catechol sulfoxides were found for compounds bearing isopropyl and tert-butyl substituents

• /3509 cm−1, respectively. For most compounds, these bands are slightly shifted to lower wavenumbers by 22–62 cm−1 relative to the corresponding thioethers. The largest shifts, ranging from 146 to 180 cm−1, are registered for compounds 6a and 7a, which contain benzyl and naphthyl substituents

• as two bands at 3522 and 3282 cm−1, whereas for sulfoxide 5a, they are observed at 3509 and 3276 cm−1. For sulfoxides containing primary/secondary aliphatic substituents (1a, 3a, 4a, 6a) or a 1-naphthyl moiety (7a), the second redox stage proceeds as an irreversible process in the potential range of

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

• scope and limitations by using various diarylacetylenes bearing the substituents on the benzene ring at para-position. The results were summarized in Table 2. Depending on the product's characteristics, either heptane or methanol was used for purification and separation. The reaction of 1,2-di-p

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

Preparation of 3-(alkylamino)imidazo[1,2-a]pyridine-2-carbaldehydes via Kornblum oxidation and unexpected ring-opening reactions of the corresponding alcohols under oxidative conditions

• Sandile J. Mkhize,
• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2026, 22, 763–770, doi:10.3762/bjoc.22.58

• 7 could be accessed from the corresponding 2-bromo derivative as shown in Figure 2 (top). Halogen substituents or a cyano group were planned at positions 5 and 6 of the imidazo[1,2-a]pyridine ring and the ortho-chloroaniline moiety was envisaged to be appended directly to position 2 because our

• 60% yield (Scheme 2). Interestingly, there appears to be only one report, in the patent literature [27], of a compound (15) containing both 2-carboxylic acid and 3-alkylamino substituents (Figure 3). The unsubstituted 3-aminoimidazo[1,2-a]pyridine-2-carboxylic acid (16) has also been reported [28

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

• characterization of new brassinosteroid (BR) analogs, in which substituents with different electronegativities and molecular sizes have been attached to a C-22 benzoate function, are described. The biological activities of all new compounds were evaluated by using the rice lamina inclination test (RLIT) and

• ]. Based on the preliminary and promissing results obtained for castasterone analogs 13 and 14, it was decided to expand this study by considering the 2α,3α diol function in ring A, a ketone function at C-6, and C-22 benzoate-function with various substituents, of different electronegativities and sizes in

• atom, are as active as the positive control 1, whereas compound 17, with a p-methyl group, is more active than 1. On the other hand, analogs 18, 20, 21 and 22, which are substituted with OCH3, Br, I and CN groups, are half as active as 12. These results indicate that small substituents with no

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

• electron-withdrawing substituents have been widely studied; acrylates, vinyl sulfones, maleimides, β-nitrostyrenes, fumarates, and maleates have been used most frequently [28][29]. Reactions of aromatic and heteroaromatic olefins containing both electron-donating and electron-withdrawing groups in the

• stronger bonds with the ligands [42]. In [49][50], a variety of dipolarophiles 22–24 containing electron-withdrawing substituents was demonstrated, which can participate in the 1,3-dipolar cycloaddition catalyzed by chiral copper complexes Cu(I) or Cu(II) with arylimines of glycine or alanine methyl esters

• the possibility of using racemic cyclopentene-1,3-diones 28 as dipolarophiles in 1,3-dipolar cycloaddition reactions using the chiral complex Ag(I)/TF-BiphamPhos (L3) (Scheme 14). The authors used various substituted diones 28 containing aromatic and aliphatic substituents, for example, silyloxy

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

• that CF3· behaves as an electrophilic radical [31][32], it was expected to react preferentially with electron-rich substrates compared to electron-neutral or electron-deficient ones. To probe this trend, trifluoromethylation was examined with substrates bearing donor substituents (methoxyarenes) and

• the meta-isomer formed in noticeably higher proportion than the para-isomer. The introduction of a methyl substituent into the anisole framework significantly altered the reactivity, with a strong dependence on the relative position of the substituents. For the meta-substituted substrate, the yield of

• ortho- or para-position, only moderate yields were obtained (50% and 45% for 15 and 16, respectively). When both methyl substituents occupied meta-positions, the yield increased markedly to 92% for 17, with 10% of the product corresponding to the doubly trifluoromethylated derivative. Interestingly

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

• observed by using complexes bearing an NHC ligand with N-alkyl substituents or a saturated backbone (Table 1, entries 5 and 6). Finally, the effect of the bulkiness of the ligand was investigated. In the presence of [Cu(Cl)(IPr*)] (5) bearing a sterically demanding NHC, 36% conversion was achieved while

Computational prediction of C–H hydricities and their use in predicting the regioselectivity of electron-rich C–H functionalisation reactions

• Rasmus M. Borup,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2026, 22, 603–610, doi:10.3762/bjoc.22.46

• out, “the reacting C–H bond tends to be electron-rich or adorned with substituents that can stabilise the formation of a developing positive charge.” It is thus possible that predicted hydricities could help predict the regioselectivity of such reactions. However, hydricity and BDEs both follow the

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

• nucleophilic aromatic substitution with thiophenols followed by oxidation with m-chloroperbenzoic acid (mCPBA). The scope of the reactions was explored, demonstrating high yields across a variety of functional groups and substituents. Optimized conditions enabled selective oxidation of thioaryl groups to

• 4-unsubstituted isoxazoles with various aryl substituents in position 3 [24][25] (approach B). One example describes the Ru-catalyzed reaction of nitrile oxide with alkynyl sulfone providing 5-sulfonylisoxazole with high regioselectivity [26] (approach C). Despite the widespread application of

• the SNAr reactions with 3-nitro- and 3-methoxycarbonyl-substituted 5-nitroisoxazoles 1a and 1g. The obtained results revealed that the nature of the substituents in the isoxazole cycle as well as in the aromatic ring of thiophenols does not have a noticeable influence on the reaction yields. The SNAr

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

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

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

• could be identified as iodized phenyl ether of melifolione A (10), based on its HRESIMS and 1H NMR spectrum. The quinols 3 or 4 could not be detected. Phenols with additional electronegative substituents (e.g., nitro or acetyl) and at least one ortho-positioned hydrogen atom initially react with

Get a better glimpse on sequential photoreactions of trisnorbornadienes with ¹⁹F NMR spectroscopy

• Julian Felix Maria Hebborn,
• Ben Eric Merten,
• Thomas Paululat and
• Heiko Ihmels

Beilstein J. Org. Chem. 2026, 22, 527–534, doi:10.3762/bjoc.22.38

• useful complementary tool [38][39][40][41]. Firstly, the 19F nucleus is only slightly less sensitive for NMR spectroscopy than the 1H nucleus [42]. Additionally, fluoro substituents may be attached such that they will give well-separated signals in less complex spectra, thus allowing conclusive and

• ortho-fluoro substituents. These substituents also induce a strong electron-withdrawing effect on the chromophore and thus lower the HOMO energy, likely leading to a larger HOMO–LUMO gap and to a small hypsochromic shift of the absorption (1f: λmax = 273 nm; parent norbornadiene 1b: λmax = 283 nm) [49

• hindrance induced by the fluoro substituents in the ortho positions [54]. It should be noted that there is only very limited data available to compare the effect of the substitution pattern on the half-life of aryl-substituted norbornadienes to support this interpretation [55]. However, the effect of ortho

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

• macrocycle. Hence, this pathway enables the quick assembly of multiple derivatives. The late-stage allene-Prins reaction also facilitates the application of other substituents on the central 3-methylenetetrahydropyran unit. On top of that, the commonly used NHK reaction involving a Cr(II)-catalyst is

A facile and practical method for the synthesis of trans-(±)-taxifolin and its derivatives via Darzens reaction

• Bo Peng,
• Panpan Yang,
• Maaz Khan,
• Xiaotong Lin,
• Jiang Wu,
• Peng Fu and
• Qingqing Wu

Beilstein J. Org. Chem. 2026, 22, 443–450, doi:10.3762/bjoc.22.31

• expanded synthesis of taxifolin derivatives with oxidant-sensitive substituents. Results and Discussion 2,4,6-Trihydroxyacetophenone was used as starting material, and its hydroxy groups were protected as methoxymethyl (MOM) ether by treatment with MOMBr (6.0 equiv) in the presence of NaH (4.0 equiv) to

• . The stereochemical outcome of the Darzens reaction may produce the α,β-epoxycarbonyl products with either the substituents on the same side or opposite side of the epoxy functionality, i.e., as cis/trans isomers. In this work, the α,β-epoxycarbonyl product contains bulky multiple-substituted benzene

• moieties (such as bis- or tris-MOMO-substituted phenyl substituents). Due to the steric hindrance, the trans-configured product with the phenyl substituents on the opposite side of the epoxy functionality is obtained. Additionally, the clean reaction process shown by TLC and the NMR spectrum of the product

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

• 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

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

• secondary amino functions strongly suppress acetylation and the embedded sulfur function contributes to the apoptosis induction [40][41].The third modification route centres on functional group engineering, in which small amine substituents are replaced with polyamines or long aliphatic chains, thereby

• into the naphthalimide framework. These differences highlight the distinct electronic environments introduced by the aryl and octyl selenium substituents. The 77Se NMR spectral data provide further confirmation. Compound 7 exhibited a 77Se NMR resonance peak at 393 ppm, while compound 8 showed a more

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

• or a trialkylammonium cation inside the joint cavity formed by two cone calix[4]arene macrocycles [46][47][48][49][50][51][52][53][54]. This phenomenon has been thoroughly investigated, including the effects from substituents in the urea groups and/or at the calixarene narrow rim upon the

• calixarene aromatic units in comparison with the ipso-nitration of the corresponding tert-butylated ones. Even larger amounts of side products were formed, thus confirming the involvement of the tightly arranged narrow-rim substituents in calixarene 6 and 7 in undesired side processes under nitration

• propargyl groups at their narrow rims. The formation of the partially nitrated calix[4]arenes 12–14 and 16 as major reaction products described above was quite unexpected, and these compounds were not used further in this study which was more concerned with calix[4]arenes having four equal substituents at

Dialkylaminoalkylation of β-ketosulfones via ring-opening of 3-sulfonylpyrrolidines

• Evgeny M. Buev,
• Alexander V. Pavlushin,
• Vladimir S. Moshkin and
• Vyacheslav Y. Sosnovskikh

Beilstein J. Org. Chem. 2026, 22, 383–389, doi:10.3762/bjoc.22.26

•  1). Altering the substituents at the sulfonyl group made no significant impact on the yield of the reaction. An application of β-ethoxycarbonylsulfone lowered the yield of the pyrrolidine 2f (53%), apparently due to the lower acidity and activity of its methylene group, however, increasing the

• , that allows a broad functionalization of the 3-(sulfonyl)butan-1-amine with various substituents and their utilization as building blocks. We believe this approach has promising features for further development and pharmaceutical applications. Valuable amino sulfonic acids and aminosulfones. Selected

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• substituents on the nitrogen (e.g., tosyl, carbamate, or acyl groups) distorts the planarity of the amide and diminishes amidic conjugation (Scheme 1b). These “twisted” amides exhibit a dramatically enhanced electrophilicity at the carbonyl carbon and a significantly weaker C–N bond strength [28][29][30][31

• electron-donating and electron-withdrawing substituents, and alkylamides having primary, secondary, and tertiary alkyl moieties at the α-position, were also suitable substrates, producing the corresponding amides 122–131 in high yields via successful generation of the acyl iodide intermediates 121

• aniline furnishing acetylanilide 158 in 87% yield. A wide range of arylamines bearing electron-donating or electron-withdrawing substituents, as well as heteroarylamines, were also competent nucleophiles, delivering the corresponding amides 159–161 in good yields. EPR studies suggested a single-electron

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• 10.3762/bjoc.22.20 Abstract Polycyclic spirobarbiturates containing a pyrrolizidine moiety were synthesized via a one-pot three-component 1,3-dipolar cycloaddition reaction of alloxan, ʟ-proline and N-substituted maleimides. The reaction stereoselectivity was found to depend on the nature of substituents

• alloxan and α-amino acids) reacted with N-methylmaleimide was published by Ronald Grigg’s group in 1994 (Scheme 3) [52]. The authors reported the synthesis of spirobarbiturates containing various substituents: R’ = iPr (67%), Bn (61%), and Ph (66%). In this work, which is a continuation of studies on the

• provided in Supporting Information File 1. Notably, for compounds 4a and 4b containing non-aromatic substituents in the succinimide moiety, the signals of protons CH4 and CH6 overlap, whereas no such overlap occurs with aromatic substituents. The assignments of the methine proton signals for all compounds

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• aromatic π-system. Such binding imparts a conjugated diene character onto the uncoordinated portion of the arene (Figure 8A). In contrast to the earlier reaction modes, the aromatic system lacks substituents or other pre-existing functionalities that would steer its reactivity. The hydrogenation of η2

• sulfone complex of W(0) (Scheme 3A) [60]. As established previously [61], protonation of η2-arene ligands bearing electron-withdrawing substituents generates reactive arenium intermediates that react with nucleophiles to furnish disubstituted η2-cyclohexadiene complexes. A second protonation/nucleophilic

A mild and atom-efficient four-component cascade strategy for the construction of biologically relevant 4-hydroxyquinolin-2(1H)-one derivatives

• Dmitrii A. Grishin,
• Kseniia I. Sharkovskaia,
• Ilya G. Kolmakov,
• Daria A. Ipatova,
• Rostislav A. Petrov,
• Nikolai D. Dagaev,
• Dmitry A. Skvortsov,
• Maria G. Khrenova,
• Valeriy V. Andreychev,
• Sergei A. Evteev,
• Yan A. Ivanenkov,
• Roman L. Antipin,
• Olga А. Dontsova and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2026, 22, 244–256, doi:10.3762/bjoc.22.18

• activity [33]. Halogen substituents in this position have been shown to modulate antibacterial, antiviral, and antiproliferative activities, likely through electronic effects and improved target binding. The C3 position was functionalized with a propanoic acid moiety, explored in both its open-chain (acid

• , is likely due to the electronic effects within pyranoquinoline. As an enol ester conjugated with an amide and an aromatic ring, electron-withdrawing groups decrease electron density on the enol OH, while aliphatic substituents (methyl, ethyl) increase electron density on the alcohol oxygen. This

Conformational analysis of difluoromethylornithine: factors influencing its gas-phase and bioactive conformations

• Matheus P. Freitas

Beilstein J. Org. Chem. 2026, 22, 237–243, doi:10.3762/bjoc.22.17

• exploring conformational effects associated with the difluoromethyl (–CHF₂) motif. The presence of vicinal fluorine substituents is known to strongly influence conformational equilibria through stereoelectronic effects, notably the fluorine gauche effect [7]. This effect arises from hyperconjugative

• complex. Elucidating this interplay is essential for rationalizing DFMO’s inhibitory potency and may also offer broader insight into how fluorinated substituents control molecular conformation in biologically relevant environments. Although the biological milieu is known to induce only minor structural

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• conditions in hand, we have investigated the oxidation of 2-acetyl-2,5-dihydrothiophenes 1, containing various substituents (Scheme 2). Cyclohexano-, cycloheptano- and cyclooctano-spiroannulated 2-acetyl-3-morpholino-N-phenyl-2,5-dihydrothiophene-2-carboxamides 1a,c,f were oxidized into 2-hydroxy derivatives

• the use of 5.0 equiv of sodium in ethanolic solution (3 mL) at rt for 1 h in air (Table 2, entry 5). With optimal conditions in hand, we have investigated the deacylation of acetyldihydrothiophenes 4a–f, containing various substituents (Scheme 4). Thus, cyclohexano-, cyclopentano-, cycloheptano- and