An Fe(II)-catalyzed synthesis of spiro[indoline-3,2'-pyrrolidine] derivatives

• Elizaveta V. Gradova,
• Nikita A. Ozhegov,
• Roman O. Shcherbakov,
• Alexander G. Tkachenko,
• Larisa Y. Nesterova,
• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2025, 21, 2383–2388, doi:10.3762/bjoc.21.183

• model ketone oxime acetate from β-3-indolyl ketone 3a using the previously described telescopic protocol [17]. This substrate was subjected to FeCl2-catalyzed spirocyclization in acetonitrile at room temperature, affording the desired spirocyclic product 4a in 70% yield as a mixture of diastereomers (dr

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• bulky stoppers at both ends to prevent dethreading (Figure 1) [1][8]. Functionalization of the axle with recognition sites allows the macrocycle to shuttle between positions in response to external stimuli, including light, redox, temperature, pH, and reactions with chemicals such as carbodiimides [9

• , temperature, and acid–base stimuli. Additionally, this spiropyran-based rotaxane showed pronounced photochromic and fluorescent behavior in both powder and solid film under alternating UV/sunlight and visible light/heating conditions, highlighting its suitability for dynamic optical systems and anti

• stiff-stilbene facilitated the formation of aggregates, resulting in organic room-temperature phosphorescence. The phosphorescent properties can be modulated by inducing macrocycle translation through acid–base stimuli or by disrupting the aggregates via stiff-stilbene photoisomerization. The authors

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

• blue LEDs at room temperature constructed a single diastereoisomer 23 in 90% yield. From 23, the ABCDE pentacyclic skeleton of phainanoids (27) was ultimately established via a Mitsunobu reaction, intramolecular nucleophilic substitution with in situ-generated aryllithium, and protecting group

• room temperature, delivering spiroacetal (S)-114 with complete retention of configuration (>99% ee). The subsequent one-pot acetylation generated (S)-115 in 83% overall yield over three steps from (S)-112. The following functional group manipulations of (S)-115 – including debenzylation/debromination

Halogenated butyrolactones from the biomass-derived synthon levoglucosenone

• Johannes Puschnig,
• Martyn Jevric and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175

• enamine 9b, which was completely consumed in 6 hours at room temperature. Following acidic hydrolysis of the enamine, a mixture of α-trifluoromethylated ketone diastereomers was obtained, and subsequent epimerization with K2CO3 afforded 19 as a single stereoisomer in 48% yield. The equatorial position of

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

• control principles for gold catalysis. Temperature-controlled cyclization of 1,n-enynes Temperature, a pivotal thermodynamic parameter, not only governs reaction kinetics but also determines reaction pathways. Typically, kinetic product formation is favored at lower temperatures via pathways with reduced

• activation barriers, while thermodynamic products dominate under elevated thermal conditions. Recent advancements have yielded novel cyclization methodologies enabling pathway control through precise temperature regulation. In 2016, the Liao group reported a temperature-regulated strategy enabling the

• and hydrogen elimination then occurred, affording 3-azabicyclo[4.1.0]hepta-2,4-diene derivatives 156. In contrast, when the temperature was raised to 110 °C, intermediate 155 underwent a 6π electrocyclic ring-opening, which was trapped by in situ-generated cyanide ions to form 4,5-dihydro-3H-azepines

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

• 100 μM target concentration (1% DMSO). In the case of 7i, 7j, (E)-9a, and (E)-9b, samples were prepared with 50 μM (1% DMSO) and 100 μM (10% DMSO) target concentration, respectively. The plate was then sealed and shaken for 2 hours at room temperature. Each compound was investigated in 3 replicates

• PBS (pH 6.5) in each well to achieve 100 μM target concentration (1% DMSO). These samples were shaken for 1 hour at room temperature then filtered the same way as the kinetic solubility samples to make initial solutions for the PAMPA assay. The artificial membrane was fabricated by dissolving ʟ-α

•  4 was applied at a constant flow rate of 1.0 mL/min. The mass spectrometer operated in sensitivity mode with a capillary voltage of 3.0 kV, source temperature was 100 °C, and desolvation temperature was 350 °C. The cone gas flow was set to 0 L/h and desolvation gas flow to 800 L/h. LockSpray

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

• at room temperature [41][42][43]. The central biphenyl moiety of conjugates 2a–h also rotates freely, forming an equilibrium mixture of P and M conformers. The relative amounts of P and M conformers depend on the chirality of the linked amine moieties. Figure 1a shows the UV and CD spectra of the

• )-5,7-dihydro-6H-dibenzo[c,e]azepin-6-yl]propan-1-ol ((S)-2a). A mixture of m-quaterphenyl probe 1 (290 mg, 0.526 mmol), ʟ-alaninol (48.3 mg, 0.643 mmol) and K2CO3 (294 mg, 2.12 mmol) in CH3CN (12 mL) was stirred at 85 °C for 3 h. After cooling to room temperature, the mixture was filtered through a pad

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

• were conducted to study the reaction process. The reaction of 1a, 2a, 3b, and 4 at 40 °C afforded the Ugi–azide product 10 in 85% yield without formation of a triazole ring, which indicates that the intramolecular click reaction needs a higher temperature (Scheme 7A). The reaction involving the

• lactamization step was carried out using 2-isocyanoacetate (9) which gave the tetrazole-fused piperazinone 6a in 93% yield, which also indicates that at this reaction temperature, lactamization could take place prior to the click reaction (Scheme 7B). Compounds 6a and 8a have same molecular weights, but their

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

• -synthesis of formamides and formates was achieved in particularly good yield by selective oxidation of DHA using a Cu/Al2O3 catalyst with single active CuII species at room temperature without using a base (Scheme 20). 1-Hydroxypropan-2-one Gu et al. reported the [3 + 2] cyclization reaction of 1

• HFO with benzoic acid amide or furan-2-carboxamide in 1:1 molar ratio at 70 °C for 4–8 h (Scheme 42, path c) [132]. The reaction of HFO with 2-methylfuran in a 1:2.2 molar ratio in diethyl ether solution at room temperature in the presence of catalytic amounts of perchloric acid for 5 hours led to the

• low miscibility with water. Investigations of the catalytic transformation of levulinic acid to 2-methyltetrahydrofuran over bimetallic NiCo/γ-Al2O3 catalyst or Ni phyllosilicates have shown that high temperature, high pressure and low selectivity are still important limitations [243][244]. Reductive

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• azobenzene derivatives [82][83][84][85][86][87][88]. From an energy charging perspective, some solvent-free systems store energy in the solid state [89] or via photoinduced solid–liquid phase transitions [61][69][74], which occur because the melting temperature (Tm) of trans-azobenzene is above room

• temperature and the Tm of the isomerized cis-azobenzene is below room temperature, while others require solvent-assisted charging mechanisms [70][71]. This structural and functional diversity makes them particularly valuable for solar thermal storage applications. Feng et al. incorporated fluorinated

• azobenzene small molecules into polymer fibers [65], enabling solvent-free charging and discharging under visible light (Figure 6a). This material exhibited good capacity for releasing high-temperature heat (80–95 °C) at room temperature and in cold environments, along with an energy storage lifetime

Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid

• Yana I. Sakhno,
• Oleksander V. Buravov,
• Kostyantyn Yu. Yurkov,
• Anastasia Yu. Andryushchenko,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158

• -triazoles, pyruvic acid, and salicylaldehydes were studied under different conditions. Upon conventional heating, benzotriazolooxadiazocine-5-carboxylic acids were formed in the three-component reactions as single reaction products. Upon ultrasonic activation or mechanical stirring at room temperature, the

• devoted to the study of the reactions of aminoazoles, pyruvic acid and its derivatives with salicylaldehydes and it was found that depending on the conditions (reaction time, temperature, and method of process activation, in particular ultrasound and microwave irradiation), different types of heterocycles

• -aminotriazoles 1a,b having pronounced electron-donating substituents (methylthio- and methoxy groups). On the other hand, the MCR of the reagents 1a, 2a–c and 3 under ultrasonic irradiation for 2 h at room temperature (25 °C) (Scheme 3) afforded a mixture of 5-(2-hydroxyphenyl)-2-(methylthio)-7-((3-(methylthio

α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• -methylisoxazol-3-yl)-5-oxo-2,5-dihydro-1H-pyrrol-3-yl]acetic acids II (Scheme 1, pathway B). Subsequently, a four-component Ugi reaction of compounds II with temperature-controlled formation of diastereomers of peptidomimetics III was also studied [52]. Taking into account all mentioned above, this work is

• isocyanide (4) in a molar ratio of 1:2:2:2 in MeOH and subsequent stirring at a temperature of 45 °C for 24 hours led to the formation of N1,N5-bis(2-(tert-butylamino)-1-(4-chlorophenyl)-2-oxoethyl)-N1,N5-bis(4-chlorophenyl)-2-oxopentanediamide (6a) in 55% yield (Scheme 2, pathway B; Table 2). Compounds 5

Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics

• Leticia A. Gomes and
• Steven A. Lopez

Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156

• and 5 (Scheme 2) through direct photolysis and with benzophenone as photosensitizer. No diastereomeric excess was observed [72] for reactions with photosensitizer. Trofimov and co-workers reported the temperature and solvent effect on the stereoselectivities [73][74][75][76] and observed a general

Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis

• Rasma Kroņkalne,
• Rūdolfs Beļaunieks,
• Armands Sebris,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154

• ) resulted in the formation of more side products (Table 3, entry 9), and we therefore decided to proceed with 5 mol % of the catalyst for the substrate scope. We also observed that, in the absence of base, even at room temperature, only the protodecupration product 12 was obtained (with up to 69% NMR yield

• ). A reaction temperature of 60 °C was found to be optimal and lower temperatures resulted in incomplete conversion. Under the optimized conditions we explored the reaction scope (Scheme 3). Unlike the previously explored dienes 10, the obtained tetrahydrofuran products 8 were easy to purify by

Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization

• Miao Xiao,
• Liuyang Pu,
• Qiaoli Shang,
• Lei Zhu and
• Jun Huang

Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152

• was initially investigated (Scheme 3). Chan’s diene (16) was subjected to condensation with freshly distilled aldehyde 17 in THF at room temperature, using a catalytic system comprising Ti(OiPr)4/(S)-BINOL complex (2.0 mol %). Subsequent deprotection with pyridinium p-toluenesulfonate (PPTS) at 0 °C

• -deficient [28], thereby lowering the energy barrier for electrophilic radical addition. Increasing the reaction temperature to 70 °C proved detrimental, yielding only trace amounts of product 14 (Table 1, entry 5). Finally, replacing Mn(OAc)3·2H2O/Cu(OAc)2·H2O with other oxidants, such as ceric ammonium

• was treated with p-toluenesulfonic acid (p-TSA) in EtOH at room temperature to afford ketal 24 in 83% yield as a single diastereomer. Subsequently, palladium-catalyzed decarboxylative allylation delivered compound 25 in 89% yield. The efficiency of our first-generation strategy for asymmetric

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• (c) MC3. (d) Molecular arrangements of MC3. Hydrogen atoms are omitted for clarity. (a) Absorptions and (b) emissions of compounds 3a, 3b, MC1, MC2, and MC3 measured in dichloromethane at room temperature. The inset shows the photographs under UV light at 365 nm. The concentration is 10 μM

• . Calculated frontier molecular orbitals and relative energy levels of MC1 (left), MC2 (middle), and MC3 (right) calculated at the B3LYP/6-31G(d) level of theory. (a) CD spectra, (b) |gabs|, and (c) glum values of enantiomers of MC1 measured in dichloromethane at room temperature. The concentrations were 10 μM

Synthesis, biological and electrochemical evaluation of glycidyl esters of phosphorus acids as potential anticancer drugs

• Almaz A. Zagidullin,
• Emil R. Bulatov,
• Mikhail N. Khrizanforov,
• Damir R. Davletshin,
• Elvina M. Gilyazova,
• Ivan A. Strelkov and
• Vasily A. Miluykov

Beilstein J. Org. Chem. 2025, 21, 1909–1916, doi:10.3762/bjoc.21.148

• h, while the temperature did not rise above 0 °C. After removal of the precipitate by filtration at 25 °C (filter consisted of layers of Celite, sodium sulfate and activated carbon), the filtrate was evaporated under reduced pressure to remove dichloromethane and excess glycidol. After vacuum

• precipitating for 12 h, while the temperature did not rise above 0 °C. After removal of the precipitate by filtration at 25 °C (filter consisted of layers of Celite, sodium sulfate and activated carbon), the filtrate was evaporated under reduced pressure to remove dichloromethane and excess glycidol. After two

• mixture with constant stirring in 1 hour. The reaction mixture was additionally stirred at −25 to −30 °C for 3 h and precipitating for 12 h, while the temperature did not rise above 10 °C. After removal of the precipitate by filtration at 25 °C (filter consisted of layers of Celite, sodium sulfate and

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

• , 5.4 mmol) and DMAP (132 mg, 1.1 mmol) in CH2Cl2 (45 mL) at room temperature. After 4 d, saturated aqueous NaHCO3 (45 mL) was added and the layers were separated. The organic layer was dried (MgSO4), filtered and evaporated. The residue was purified by column chromatography on silica gel, eluting with

• , dimethyl sulphide (51.3 mL, 693 mmol) was added, and the mixture was warmed to room temperature and stirred. After 16 h, the solvent was evaporated and the residue was purified by column chromatography on silica gel, eluting with EtOAc/petrol 1:1. The product was recrystallised from n-hexane/CH2Cl2 to give

• -methylmaleimide (255 mg, 2.30 mmol) was added and the mixture was heated under reflux. After 3 h, further N-methylmaleimide (128 mg, 1.84 mmol) was added, and the mixture was heated under reflux for a further 1 h. The mixture was cooled to room temperature and the solvent was evaporated. The crude product

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• enantioselective synthesis of planarly chiral macrocycles through a dynamic kinetic resolution approach [15]. Despite bearing an amino group on the phenyl ring, the configuration of the macrocyclic paracyclophane 32 was found to be unstable at room temperature. Consequently, by employing a CPA-catalyzed asymmetric

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

• with a photoswitch, several factors must be considered: substituents, temperature, and solvent strongly affect the photophysical properties. For instance, the presence of electron-withdrawing (for instance -Cl, -Br, -CN, -NO2) and electron-donating groups (-alkyl, -OR, -NR2), which are directly

• the time within 50% of the metastable isomer is thermally converted to the stable one [3]. It depends on the photoswitch class, solvent, substitution pattern, and temperature. For some photoswitch classes, proton exchange and intramolecular hydrogen bonds are known to accelerate the thermal relaxation

Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp²)–C(sp²) bond scission of styrenes

• Prafull A. Jagtap,
• Manish M. Petkar,
• Vaishnavi R. Sawant and
• Bhalchandra M. Bhanage

Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142

• observed when the amount of trifluoroacetic acid (TFA) was reduced from 1.5 equiv to 1.0 equiv (Table 1, entry 12). Consequently, in the absence of the additive, the yield was significantly diminished due to the incomplete consumption of 1a (Table 1, entry 13). Lowering the temperature to 100 °C

• 26% yield. Then, in reaction 3, a one-pot, two-step reaction involving phenylglyoxalic acid (2aa) was carried out. In step 1, compounds 1a and 2aa were stirred at room temperature for 5 minutes in the presence of a catalyst and an additive. Subsequently, in step 2, styrene (2a) was added, and the

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• times. This bis-vesicle structure possesses the following intelligent responsive characteristics: (1) temperature sensitivity originating from the enthalpy-driven nature of the host–guest interaction; (2) redox responsiveness due to the reversible electron transfer of MVC12; (3) competitive complexation

• making the system sensitive to cyclodextrins. Experiments have confirmed that this carrier can efficiently encapsulate DOX and trigger drug release through multiple stimuli, demonstrating good potential for anticancer therapy in vitro. This intelligent delivery system, integrating temperature, redox, and

• binary vesicle system based on WP6 and SAINT molecules (G5), which exhibits multiple stimulus-responsive characteristics to pH, Ca2+ and temperature (Figure 20). WP6 and G5, as amphiphilic molecules containing pyridine groups and alkyl chains, form supramolecular amphiphiles through host−guest

Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue

• Mai Uchibori,
• Nanami Murate,
• Kanako Shima,
• Tatsunori Sakagami,
• Ko Kanehisa,
• Gary James Richards,
• Akiko Hori and
• Osamu Kitagawa

Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138

• vapour diffusion of hexane into a methanol solution of the compound at room temperature) and their X-ray crystal structural analyses were performed (Figure 2) [33]. In the crystals of rac-1a, a π-type intermolecular interaction between the bromine atom and the benzene ring of the quinolinone was found

• observed in the crystals of optically pure forms (P)-1a,b (Figure 3, single crystals of (P)-1a,b were obtained by vapour diffusion of hexane into a methanol solution of the compound at room temperature) [34]. Meanwhile, the halogen atoms in (P)-1a,b were found to interact with the C4 atom on the lactam

• racemic quinolinones rac-1 in Figure 2 (single crystals of rac-2a were obtained from slow evaporation of hexane/methanol (1:1) mixture at room temperature) [37]. That is, in contrast to rac-1, in which homochiral layered polymer chains were formed, crystallization of quinoline-2-thione rac-2a led to the

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

• are uncorrected. tert-Butyl 3-(2-methoxy-2-oxoethyl)-1H-indole-1-carboxylate (21). A solution of indol-3-yl acetic acid (20, 5.1 g, 29.0 mmol, 1.0 equiv) in dry MeOH (200 mL) was cooled to 0 °C, and SOCl2 (10.5 mL, 145 mmol, 5.0 equiv) was added slowly. After stirring for 12 h at room temperature, the

• DMAP (0.63 g, 5.2 mmol, 0.2 equiv) were added [32]. The mixture was stirred for 2 h at room temperature after which the solvent was removed under reduced pressure. The residue was dissolved in EtOAc (250 mL) and subsequently washed with saturated aqueous NH4Cl (150 mL), saturated aqueous NaHCO3 (150 mL

• , 3 equiv) in H2O (250 mL) was added to a solution of 21 (5.0 g, 17.2 mmol, 1.0 equiv) in THF (300 mL) and MeOH (150 mL). After stirring for 18 h at room temperature, the mixture was concentrated in vacuo and a 10% aqueous solution of citric acid (100 mL) was added. The aqueous layer was extracted

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• (69/61/72% over two steps, see Figure 6). However, only if temperature and reaction times in this step were carefully controlled, the reaction proceeded cleanly. Deviations from the optimized conditions (see Supporting Information File 1 for details) resulted in greatly diminished yields due to the