Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water

• Michaela Šusterová and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201

• remains a major challenge due to the strong hydration of anions. Here, we report the preparation of silica gel functionalized with covalently anchored bambusuril macrocycles. In aqueous solution, this material efficiently sorbs dicyanoaurate(I), the key anion in gold mining, even in the presence of

• leading not only to improved extraction effectivity but also to enhanced selectivity [2]. Anion extractants based on functionalized polystyrene or silica gel typically incorporate calixarenes [6] and their analogues, calixpyrroles [7][8], azacalixarene derivatives [9], or expanded porphyrin-like sapphyrin

• functionalized, for instance by carboxylic moieties [13], making them available for further reactions with different substrates. We have recently presented a material (SG-BnBU) based on silica gel containing dodecabenzylbambus[6]uril (BnBU) non-covalently bound on its surface [14]. We showed that this material

Recent advances in total synthesis of illisimonin A

• Juan Huang and
• Ming Yang

Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199

• product. They resolved racemic intermediate 27 by derivatization with (S)-1-(1-naphthyl)ethyl isocyanate, followed by separation of the resulting diastereomers via silica gel chromatography (Scheme 3). By converting diastereomer 32 to (−)-illisimonin A, the absolute configuration of the natural product

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• is secured from the commercial source. Results and Discussion Based on the known protocol [33], diacetone-ᴅ-allofuranose 8 was first introduced with a propargyl group (Scheme 2A). Upon treatment of AcOH to afford diol 9, oxidative cleavage with Shing’s protocol (NaIO4 on silica gel) [34] proceeded

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• mixture was filtered through a Celite pad, and the filtrate was concentrated using a rotary evaporator. The crude residue was purified through silica gel column chromatography using n-hexane/EtOAc 99:1 as eluent to give the pure C1-nitrated carbazole 2. ORTEP diagram of compound 2a (CCDC 2478298

Ex-situ generation of gaseous nitriles in two-chamber glassware for facile haloacetimidate synthesis

• Nikolai B. Akselvoll,
• Jonas T. Larsen and
• Christian M. Pedersen

Beilstein J. Org. Chem. 2025, 21, 2465–2469, doi:10.3762/bjoc.21.188

• of difluoroacetimidates was therefore attempted, but in our hands, these proved even more unstable than the trifluoroacetimidates and were not possible to isolate by chromatography due to decomposition. However, the purity of these compounds, after filtration through a block of silica gel, was

• was the p-methoxy derivative 11 which, as expected, was more reactive and hence more difficult to purify due to decomposition on silica gel. The p-methoxybenzyl trifluoroacetimidate (9) has been shown to be an effective regent for the acid-catalyzed benzylation of alcohols [12][30]. Conclusion In

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• 90% yield to (+)-stephadiamine (71). The authors noted that the identification of the structure of (+)-stephadiamine (71) was carried out without purification of the reaction mixture due to its instability on a silica gel column under acidic or basic conditions. Zhang et al. [47] proposed an

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• performed using silica gel (60 F254, Merck, Darmstadt, Germany) plates. Melting points were recorded using a Büchi melting point B-540 apparatus (Büchi Labortechnik AG in Flawil, Switzerland). The IR spectra were measured by Spectrum Two FT-IR spectrometer (PerkinElmer, Massachusetts, USA). The NMR spectra

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• southern furan moiety of 69. Finally, hydrolysis of the carbonate followed by oxidation of the resulting diol completed the Norrish–Yang cyclization precursor gracilisoid A (49). Irradiation of 49 under anaerobic conditions with a CFL, followed by treatment with silica gel, successfully generated a pair of

• separable regioisomers: gracilisoid F (54) in 42% yield and gracilisoid H (56) in 40% yield, respectively (Scheme 8). Here, light triggered a regiodivergent Norrish–Yang cyclization, while the acidic nature of silica gel sufficiently promoted an α-hydroxy ketone rearrangement. This type of rearrangement was

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• activated ynamide. This sequence resulted in the formation of spiroindoleninium intermediate 130 (Scheme 27, path a). Subsequent intramolecular Mannich cyclization proceeded, yielding the 1H-pyrrolo[2,3-d]carbazole derivatives 131. When silica gel was utilized as the catalytic medium, the same Michael

• addition happened to generate the spiroindoleninium intermediate. This transient species was subsequently trapped by water physisorbed in the silica gel, forming hemiaminal adduct 132. A 1,5-hydride shift was then mediated by Al2O3, ultimately affording the spiro[indoline-3,3'-pyrrolidin]-2-one derivatives

Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates

• Gyöngyvér Pusztai,
• László Poszávácz,
• Anna Vincze,
• András Marton,
• Ahmed Qasim Abdulhussein,
• Judit Halász,
• András Dancsó,
• Gyula Simig,
• György Tibor Balogh and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169

• spectrometer equipped with a Direct Insertion Probe (EI+ ionization) or on a Bruker Q-TOF Maxis Impact mass spectrometer (ESI+ ionization) coupled with a Waters Acquity I-Class UPLC system equipped with a diode array detector. The reactions were followed by analytical thin-layer chromatography on silica gel 60

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• structure analysis was performed on a Bruker SMART diffractometer equipped with a CCD area detector at 120 K. Silica gel 60 F254 precoated plates on glass from Merck Ltd. were used for thin-layer chromatography (TLC). General procedure for the synthesis of conjugates 2a–h (S)-2-[2,10-Bis(4-methoxyphenyl

• of Celite, and then evaporated to dryness. The crude product was purified by column chromatography on silica gel (EtOAc) to yield amine (S)-2a (203 mg, 83% yield) as colorless solid: mp 164.2–165.5 °C; 1H NMR (400 MHz, CDCl3) δ 7.73 (d, J = 1.8 Hz, 2H), 7.62–7.56 (m, 6H), 7.44 (d, J = 7.8 Hz, 2H

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• mixture was evaporated to remove MeOH solvent and the residue was redissolved in MeCN (2 mL) and heated at 130 °C for 2 h in a sealed vial. After the reaction had reached completion as monitored by TLC, the reaction mixture was concentrated in vacuo. Column chromatography on silica gel afforded products

Bioinspired total syntheses of natural products: a personal adventure

• Zhengyi Qin,
• Yuting Yang,
• Nuran Yan,
• Xinyu Liang,
• Zhiyu Zhang,
• Yaxuan Duan,
• Huilin Li and
• Xuegong She

Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160

• was then treated with AcOH to afford the putative iminium cation to be chemoselectively reduced with NaBH3CN to ultimately reach the amine functionality. Through this protocol, the amine product was obtained, but it could not be isolated from silica gel for its high polarity. Thus, the extracted crude

Stereoselective electrochemical intramolecular imino-pinacol reaction: a straightforward entry to enantiopure piperazines

• Margherita Gazzotti,
• Fabrizio Medici,
• Valerio Chiroli,
• Laura Raimondi,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2025, 21, 1897–1908, doi:10.3762/bjoc.21.147

• CH2Cl2 (3 × 10 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under vacuum. The reaction crude was purified by flash column chromatography on silica gel (n-hexane/ethyl acetate 8:2) to give the desired pure product. General procedure for in-flow electrochemical imino

• purified through flash column chromatography on silica gel to give the isolated pure product. X-ray determined structure of chiral piperazine 2b. Synthesis of vicinal diamines via imino-pinacol coupling in the presence of metal-based reductants. Light-promoted imino-pinacol coupling for the synthesis of

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• chromatography on silica gel. The structure of this isomer could not be ascertained with certainty from NOESY analysis and initial crystallisation attempts were unsuccessful. However, through use of encapsulated nanodroplet crystallisation (ENaCt), a high-throughput crystallisation technique which controls the

• silica gel 60F254 plates and visualised by UV irradiation at 254 nm or by staining with an alkaline KMnO4 dip. Flash column chromatography was performed using silica gel (40–63 micron mesh). Infrared spectra were recorded on a Perkin Elmer Spectrum RX Fourier Transform–IR System and only selected peaks

• ), dried (MgSO4), filtered and evaporated. The residue was purified by column chromatography on silica gel, eluting with EtOAc/petrol 1:2, to give the alcohol 2 (824 mg, 30%) as an amorphous solid; data as reported [30]. Et3N (1.5 mL, 10.8 mmol) was added to the alcohol 2 (782 mg, 3.6 mmol), TsCl (1.03 g

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• ), and brine (100 mL). After drying over anhydrous MgSO4, the solvent was removed in vacuo and the crude product was purified by flash chromatography on silica gel (EtOAc/hexane; gradient 1:10 → 1:2) to give 21 as a colorless solid (6.7 g, 80%, 2 steps); Rf = 0.5 (EtOAc/hexane 1:2); mp 50–52 °C (lit. mp

• with EtOAc (3 × 50 mL) and the combined organic layers were washed with water (100 mL) and brine (100 mL), and then dried over anhydrous MgSO4. The solvent was removed under reduced pressure and the residue was purified by flash chromatography on silica gel (EtOAc/hexane gradient 1:10 → 1:1, 1% AcOH

• ), followed by brine (40 mL). The organic layer was dried over anhydrous Na2SO4, and the solvent was evaporated under reduced pressure. The residue was purified by flash chromatography on silica gel using a gradient of EtOAc/hexane (1:10 → 1:1), affording compound 23 as a colorless viscous oil (425 mg, 50

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• . tuberculosis [121]. The TMS-glycosides were prepared from the corresponding hemiacetals by acid-catalyzed silylation, involving a silica gel-promoted in situ anomerization of the O-TMS-β-glycoside to its more thermodynamically stable α-counterpart [121]. This protocol enabled the efficient synthesis of TMS

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• standard. Analytical thin-layer chromatography (TLC) was performed with silica gel 60 Merck F254 plates. Column chromatography was performed with silica gel 60N (spherical neutral). Recyclable preparative high-performance liquid chromatography (HPLC) was carried out on a Japan Analytical Industry Model

Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins

• Juliana V. Petrova,
• Varvara T. Tkachenko,
• Victor A. Tafeenko,
• Anna S. Pestretsova,
• Vadim S. Pokrovsky,
• Maxim E. Kukushkin and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118

• chromatography on silica gel using DCM as eluent. Design and synthetic strategies for the target hydantoin/1,2,4-oxadiazoline spiro-compounds. Atropoisomerism of ortho-substituted spiro-compounds 5b and 5d. Cytotoxicity investigation of hydantoin/1,2,4-oxadiazolines 5 (MTT test, HCT116 cell line) and selected

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• Commercial chemicals and solvents were used as received. If not stated otherwise, products were purified by filtration through short silica gel plugs (200–400 mesh) by using freshly distilled solvents as eluents or by recrystallization. Melting points were determined in capillaries with an Aldrich Melt-Temp

• evaporated, and the residue was analyzed by 1H NMR. Depending on the composition of the crude product, this material was either separated by preparative layer chromatography on the plates coated with silica gel (CH2Cl2 as the mobile phase) (separation of 9h and 10h) or crystallized from hexane/CH2Cl2 mixture

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• foundation, the same group in 2024 developed a series of structurally refined aza[7]helicenes (compounds 12a and 12b) under modified Scholl reaction conditions [25]. These products were obtained as optically active diastereomers, which were successfully separated using silica gel chromatography. Additionally

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• Fluorochem and used as received. The solvents used for the experimental synthesis (HPLC grade) were purchased from Sigma-Aldrich. All other materials were commercial products of analytical grade and used as supplied. Analytical TLC (thin-layer chromatography) was performed on Merck silica gel 60 F254

• on silica gel, using dichloromethane/ethyl acetate 6:1 as eluent to obtain the pure product as bright orange solid (0.31 g, 62% yield). 1H NMR (500 MHz, CDCl3) δ 8.93 (dd, J = 1.2 Hz, 4.6 Hz, 1H), 7.95 (d, J = 8.0 Hz, 1H), 7.87 (d, J = 8.0 Hz, 2H), 7.70 (d, J = 9.5 Hz, 1H), 7.49 (t, J = 8.0 Hz, 2H

• formed, was washed with water several times and dried. The crude material was purified by column chromatography on silica gel, eluting with dichloromethane. Evaporation of the solvent afforded the pure target compound as orange solid (0.26 g, 38% yield). 1H NMR (500 MHz, DMSO-d6) δ 14.7 (br s, 1H), 8.90

Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles

• Vladimir G. Ilkin,
• Pavel S. Silaichev,
• Valeriy O. Filimonov,
• Tetyana V. Beryozkina,
• Margarita D. Likhacheva,
• Pavel A. Slepukhin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104

• solution was stirred for 10 min in an ice bath, then iodonium salt 2a or 2f (1.5–2.0 equiv) was added in one portion. The reaction vessel was removed from the ice bath and the reaction mass was stirred for 6–60 min, then transferred to a silica gel column and the corresponding 2-sulfonyl-2,3-dihydro-1,2

• (1.5 mL) was added dropwise. The reaction vessel was removed from the ice bath and the reaction mass was stirred for 10–30 min, then transferred to a silica gel column and the corresponding 2-sulfonyl-1,3-thiazole 3 was isolated. X-ray structure determination of 3aa. Crystal data for C21H21N3O3S2 (M

Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents

• Julius Krenzer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97

• in Table 1. The yield of compounds 1 after flash chromatography on silica gel under modified conditions (B) are significantly higher than under standard conditions (A). The results demonstrate the broad applicability of the optimized reaction conditions. Acid chlorides with electron-withdrawing (-CN

• ® and purified by flash chromatography on silica gel (n-hexane/acetone 3:1). Then, the crude product was suspended in n-hexane, the supernatant separated by filtration and the precipitate was dried under vacuum to afford aroyl-S,N-ketene acetal 1i (1.78 g, 4.93 mmol, 99%) as a yellow solid. Mp 159 °C

Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates

• Alexander S. Budnikov,
• Igor B. Krylov,
• Fedor K. Monin,
• Valentina M. Merkulova,
• Alexey I. Ilovaisky,
• Liu Yan,
• Bing Yu and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96

• chromatography on silica gel. Recent approaches for the synthesis of β-ketophosphonates by the oxyphosphorylation of unsaturated compounds. The scope of the discovered copper(II)-mediated phosphorylation of enol acetates. Gram-scale synthesis of 3a. Control experiments. Proposed mechanism for copper(II) mediated