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

• proteins by the PELDOR method at room temperature [2]. Piperidine nitroxyl biradicals form the basis of the most efficient commercial agents for dynamic nuclear polarization (DNP) in NMR studies of biomolecules and solid samples [3]. They are also employed as contrast agents for magnetic resonance imaging

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

• ) were subsequently evaluated by adding aniline to activated olefins (Scheme 3) [35][36]. Using 5 mol % of the copper–amido catalyst at room temperature, the α,β-unsaturated substrates including acrylonitrile, methyl vinyl ketone, methyl acrylate, and cyclic enones were converted to the corresponding β

• that under conditions A, copper nanoparticles (CuNPs, 1.2 mol %) efficiently promoted the aza-Michael addition of anilines to activated alkenes at room temperature (Scheme 11a) [49]. In this system, the nanoparticulate copper surface acts as a Lewis acid to activate the Michael acceptor 33 through

• -supported copper nanocomplex, Cu(0)NC@PHA, derived from cellulose-based poly(hydroxamic acid) ligands [50]. The supported Cu(0) NPs catalyzed aza-Michael addition reactions of aromatic amines with various α,β-unsaturated esters 33 in ethanol at room temperature. The heterogeneous catalyst exhibited high

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

• 1a–c were treated with 2.5 equiv of n-BuLi in anhydrous THF at −78 °C under a nitrogen atmosphere to generate the corresponding aryllithium intermediates, followed by introduction of CO2 via a balloon. The reaction mixture was then allowed to warm to room temperature and stirred overnight to ensure

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

• MeCN) for the reaction of azirine 1a and benzaldehyde (2c, Scheme 3). Calculations indicate that condensation and subsequent cyclization should readily occur at room temperature, with only the diastereoisomer (1RR,3SR,6RR)-Phe-C (with the Ph group from benzaldehyde in the equatorial position

Chiral cyclopropenimine-catalyzed enantioselective Michael reactions of phenol and benzofuran-derived α,β-unsaturated pyrazolamides with benzophenone-imine of glycine esters

• Ya Bai,
• Xue-Ying Wang,
• Si-Kai Zhu,
• Yan-Ting Shen,
• Sheng-Yong Zhang and
• Ping-An Wang

Beilstein J. Org. Chem. 2026, 22, 888–896, doi:10.3762/bjoc.22.69

• the catalytic effect of CSB-1. Based on these results, the optimal reaction conditions are listed in Table 1, entry 1. The reactions between 2 and 5 were carried out in EtOAc by using 20 mol % of CSB-1 as a catalyst at room temperature. With the optimal conditions in hand, the asymmetric Michael

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

• moderate yields with good diastereoselectivity. Reaction with cyclohexanone led to partial elimination, which proceeded to completion upon warming the reaction mixture to room temperature, affording the bora-Wittig product 6j in moderate yield [39]. Furthermore, an intramolecular reaction was investigated

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

• modification. The chemical or enzymatic steps are generally mild (room temperature, aqueous buffer) yet highly specific. However, the main limitation is that only glycosylated proteins (especially IgGs) can be targeted. Intrinsic glycan heterogeneity can also lead to incomplete functionalisation. Biological

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

• (II) congener, K[PtCl3(ethylene)] [28], as well as the first examples of gold(III) alkyne [29], CO [30], hydride [31] and σ-complexes [32] (Scheme 3). The olefin complexes were isolated as microcrystalline powders which as dry solids are fairly stable in air at room temperature. The olefin bonding is

• ^C^N complex 12 (H trans to C) is stable in THF solution at −20 °C but decomposes at room temperature. This instability of 12 may in part also be due to the tendency of the pyridine arm to dissociate; for example, on addition of LiHBEt3 the pyridine is displaced to give the dihydrido complex Li[(N–C

• ^C)AuH2] [50]. Goldberg’s complex 13, on the other hand, which is stabilised by two strongly donating P(t-Bu)2 moieties, is stable at room temperature and could be crystallographically characterised [53]. A gold hydride of type 12 has been postulated as an intermediate in the thermal decomposition of

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

• , frequently employed as a model system to study the activity of catechol oxidase and tyrosinase. Although hydrogen peroxide is a strong oxidant, its reaction with 3,5-DTBC is often slow at room temperature in the absence of a catalyst, typically requiring metal ions such as Cu2+, Fe3+, or Co2+ [43]. Moreover

• {1H} NMR spectroscopy (Figures S1–S20), HRMS (Figures S21–S26) in Supporting Information File 1, and elemental analysis. X-ray data The X-ray suitable crystals of 1a, 4a–7a were grown by slow recrystallization of the compounds from acetonitrile or chloroform (for 7a) solutions at room temperature. The

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

• ). Reduction of 24 with NaBH4. NaBH₄ (95 mg, 2.52 mmol, 2 equiv) was added in portions to a stirred solution of 24 (0.40 g, 1.26 mmol, 1 equiv) in MeOH (15 mL) at room temperature. The mixture was stirred for 2 h, poured onto ice, and the resulting yellow precipitate of 25 was collected by filtration (295 mg

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• ), ammonium acetate (60.5 mg, 0.79 mmol), and aldehyde (0.20 mmol) in glacial acetic acid (5 mL) was heated to 110 °C with stirring for 12 h. The resultant solution was cooled to room temperature and neutralized with aqueous ammonia solution (25%) to pH 6. The precipitate of a product was filtered off and

• toluene (5 mL) was heated to 110 °C with stirring for 12 h. The resultant solution was cooled to room temperature and neutralized with aqueous ammonia solution (25%) to pH 6. The precipitated compounds (see Table 1) were isolated by filtration followed by washing sequentially with portions of water

• stirred at room temperature for 2 h and then poured into water and extracted with chloroform. The extract was dried over MgSO4 and concentrated under reduced pressure. The products were purified by column chromatography on silica gel using ethyl acetate as eluent. General method (B2) for the condensation

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

• heated by a heating gun. After cooled to room temperature, the flask was filled with N2. FeBr3 (154.2 mg, 0.52 mmol) and NBS (N-bromosuccinimide, 196.0 mg, 1.10 mmol) were added to the glass flask. Then, CH2Cl2 (dry, 2.0 mL) and 1,2-diphenylacetylene (1a, 89.4 mg, 0.502 mmol) were added and the mixture

• was stirred at room temperature for 2 hours. A 10% aqueous solution of Na2S2O3 (20 mL) was added to stop the reaction. The mixture was extracted with CH2Cl2 (20 mL × 1), and separated. The aqueous phase was extracted with CH2Cl2 (20 mL × 2). The combined organic phase was washed with H2O (20 mL) and

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

• -methyl groups cannot freely rotate past the nearby sulfone oxygen atoms. Calculations suggested a rotation barrier of 18 kcal/mol, consistent with it being insurmountable at room temperature, vs only 4 kcal/mol for the unsubstituted phenyl ring (see Supporting Information File 1). The combined results of

• sulfinates. In contrast, performing the competition experiment at room temperature gave a different product profile in which a good yield of 26 (62%) precipitated from the reaction mixture. No other products were observed in either the precipitate or the extracted filtrate from that reaction. The high

• 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

• )benzylamine (92) as an azomethine ylide precursor in (3 + 2)-dipolar cycloaddition reactions with electron-deficient exo-cyclic 93 and endo-cyclic alkenes 94 (Scheme 36) [77][78][79]. To generate the azomethine ylide from reagent 92, TFA in methylene chloride at room temperature or LiF in acetonitrile with

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

• reaction using N-bromosuccinimide (NBS) in CH2Cl2 at room temperature (1 h), we produced 5 as a single enantiomer (i.e., (+)-5,5'-dibromopinoresinol). Herein, we report the full spectroscopic and spectrometric characterization of this molecule. Furthermore, analogues 6 and 7 are new semisynthetic molecules

• plates were used for TLC and analyzed under UV light at 254 and 365 nm. For large-scale studies, the plant material was extracted at room temperature using an Edwards Instrument Company Bio-line orbital shaker set to 200 rpm. All chemical reagents used throughout the experiments were purchased from Sigma

• (+)-pinoresinol derivatives 3–7 Methylation of (+)-pinoresinol (2) (+)-Pinoresinol (2, 15.8 mg, 0.044 mmol) was dissolved in MeOH/CH2Cl2 1:1 (250 μL) before (trimethylsilyl)diazomethane (2.0 M in diethyl ether, 150 μL) was added dropwise. The reaction mixture was stirred for 20 min at room temperature and then

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

• -trimethoxybenzene (TMB) as the substrate and 3 equivalents of TFAA as the CF3 source, over 6 hours at room temperature (25 °C). Initially, white light irradiation was selected owing to its broad coverage of the visible spectrum (Supporting Information File 1, Figure S6). Screening of various organic photocatalysts

• reaction conditions were established as follows: 2 mol % 3DPAFIPN in EtOAc under blue-light irradiation (450 nm) at room temperature (23 °C) for 6 h under an argon atmosphere. Using the optimized conditions, the scope of the developed protocol was evaluated with a range of arenes and heteroarenes (Scheme 2

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

• our delight, upon reacting in toluene equimolar amounts of FA and PhSiH3, efficiency increased (Figure 2). Indeed, by using 1a and its tert-butoxide congener 1c ([Cu] = 10 mol %) a violent evolution of gas was observed at room temperature, resulting into a considerable increase of pressure which

• experiments were carried out (Scheme 2). By reacting FA and PhSiH3 (1:1 molar ratio) in the presence of 10 mol % of 1a, in deuterated toluene at room temperature under D2 atmosphere (1 atm), no H–D scrambling was observed (Scheme 2a). Furthermore, the 1a-catalyzed reaction of FA labeled at the acidic position

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

• times (Table 1). It was found that the reaction proceeds completely to give the exhaustive oxidation product 3a, when 2a was treated with 2.5 equivalents of mCPBA at room temperature. Thus, we used these conditions as the standard reaction conditions for our further studies. Additionally, it was found

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

• continuous-flow hydrogenation of a ketone We compared the catalytic performance of the newly prepared bimetallic catalysts to that of commercially available heterogeneous Pt catalysts in the continuous-flow hydrogenation of acetophenone (1a) at room temperature. The heterogeneous catalysts were packed into a

• column with Celite, with the molar amount of Pt adjusted to 0.006 mmol within the column. Both the solution of acetophenone (1a) in ethyl acetate (EtOAc) and hydrogen gas were simultaneously passed through the catalyst-packed column without backpressure control at room temperature (Scheme 1). The powder

• = 0.62‒2.3) (Scheme 2, Figure 1, and Table 2). 4’-Methoxyacetophenone (1b) and 4’-methylacetophenone (1c) were quantitatively hydrogenated to the corresponding alcohols 2b and 2c under continuous-flow conditions at room temperature (Table 2, entries 1 and 2). The bulky substrate 2-acetylnaphthalene (1d

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

• -(dimethylamino)pyridine (DMAP, 2 mg) were added and the mixture was stirred at room temperature for 24 hours. Then, the solution was cooled to 0 °C and 100 mL of 2 M HCl added and stirred for 5 min. The mixture was extracted with ethyl acetate (4 × 30 mL). The organic phase was washed with saturated NaHCO3 (2

• 0 °C. m-CPBA (77%, 0.73 g, 3.26 mmol) and NaHCO3 (0.282 g, 3.36 mmol) were added and the mixture was stirred at room temperature for 36 hours. Then, the solution was cooled to 0 °C and 100 mL of 3 M NaOH added, and stirring continued for 40 min. The mixture was extracted with CH2Cl2 (4 × 30 mL). The

• at room temperature to obtain colourless crystals, mp: 101–102 °C. Compound 11 was recrystallized from the same solvent mixture at 0 °C and obtained as slightly yellow crystals, mp: 117–119 °C. (1S*,2S*,5S*,6S*)-6-Acetoxy-2-azido-5-chlorocyclooctyl 4-nitrobenzoate (10): 1H NMR (400 MHz, CDCl3) δ 8.34

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

• -toluenesulfonic acid at 80 °C in toluene afforded benzoxocin (7) as the only product. On the other hand, melifolione A (1) was completely decomposed under these conditions. Irradiation of 5 in methanol with UV-light (300 nm) for 3 days at room temperature gave melifolione B (2) with traces of melifolione A (1

• -trihydroxyacetophenone (3.7 g, 20 mmol), citral (3.2 g, 21 mmol) and pyridine (1.6 g, 20 mmol) was heated with stirring in a water bath at max. 60 °C for 8 h. After cooling to room temperature, the reaction mixture was diluted with 200 mL diethyl ether and extracted with 0.1 N H2SO4 (3 × 20 mL) to remove the pyridine

• tube and heated in a microwave apparatus (CEM, model DISCOVER, power 300 Watt) up to 140 °C for 20 minutes. After cooling to room temperature, the reaction mixture was dissolved in 200 mL diethyl ether. This solution was washed with 0.1 N NaOH (3 × 20 mL) and water (1 × 20 mL), dried over MgSO4

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

• ]heptadien-2-yl)-1,3,2-dioxaborolane (1e, 501 mg, 2.30 mmol), Pd(PPh3)4 (66.5 mg, 57.5 µmol, 5 mol %), THF (5.0 mL), and aq. NaOH (5.7 mmol, 2.7 M, 2.1 mL) was stirred at 80 °C for 16 h under anaerobic conditions [22]. After cooling the emulsion to room temperature, EtOAc (15 mL) was added and the organic

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

• calixarene tetraethylacetate [53]. In the original procedure, KOH was added at −5 °C, and the mixture was stirred for 5 hours at this temperature, followed by 5 days of stirring at room temperature. In our hands, both the addition of KOH and stirring were performed entirely at room temperature, and 1H NMR

Structural reassignment of compound 968, an allosteric glutaminase inhibitor

• Lindsey A. Albertelli,
• Sainabou Jallow,
• Chun Li and
• Scott M. Ulrich

Beilstein J. Org. Chem. 2026, 22, 455–460, doi:10.3762/bjoc.22.33

• -dimethylaminobenzaldehyde 4-Dimethylaminobenzaldehyde (4.02 g, 26.9 mmol) was dissolved in 1,4-dioxane (52 mL) and NBS (5.01 g, 28.2 mmol) was added in small portions with stirring over 5 minutes. The reaction mixture was stirred at room temperature for 20 minutes then poured into 50 mL water. The mixture was diluted with

• solution of the test compound in DMSO or DMSO itself was added (1 µL), mixed by gently pipetting up and down, then incubated for seven minutes at room temperature. The glutaminase reaction was initiated by addition of 20 µL of a solution of glutamine (100 mM) and K2HPO4 (500 mM), then mixed by gently

• pipetting up and down and incubated at room temperature for seven minutes. The reactions were quenched by addition of cold 3 M HCl (10 µL). An aliquot (10 µL) of each quenched GAC reaction was added to 190 µL of a glutamate dehydrogenase reaction which consisted of a solution containing Tris-HCl (100 mM, pH

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

• give protected acetophenone 1 in an excellent yield of 78%. Next, the reaction conditions for the following α-bromination of acetophenone 1 to intermediate 2 were screened (Table S1, Supporting Information File 1). The treatment of compound 1 with CuBr2 in EtOAc at either room temperature or 60 °C

• all the Lewis acids screened, ZnCl2 was associated with best yield of 90%. Overall, the optimal conditions for the Darzens reaction involved treatment of 2 (1.0 equiv) with 3a (1.2 equiv) in MeCN at room temperature, using t-BuOLi (1.2 equiv) as the base and ZnCl2 (0.1 equiv) as Lewis acid catalyst

• mmol, 1.0 equiv), 3 (1.2 equiv), t-BuOLi (1.2 equiv) and ZnCl2 (10 mol %) in CH3CN (4.5 mL), stirred at room temperature for 4–6 h, N2 atmosphere. aZnCl2 was not added and the reaction time was 15 h. Yields are isolated yields. Synthesis of trans-(±)-taxifolin and its derivatives via the approach