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Search for "cyclic" in Full Text gives 1268 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Copper catalysis: a constantly evolving field
Beilstein J. Org. Chem. 2025, 21, 1477–1479, doi:10.3762/bjoc.21.109
- substitution pattern on the regioselectivity and stereoselectivity of the reactions. A Review article by Papis and co-workers discusses various copper(II) triflate-catalyzed multicomponent reaction types [2]. Therein, the synthesis of cyclic and acyclic compounds, as well as three-component and four-component
Microwave-enhanced additive-free C–H amination of benzoxazoles catalysed by supported copper
Beilstein J. Org. Chem. 2025, 21, 1462–1476, doi:10.3762/bjoc.21.108
- Cu(I) derivative. Next, the scope of the optimised heterogeneous MW-assisted protocol was tested with a set of 16 different secondary amines (Scheme 3). This set included linear, branched aliphatic, and cyclic amines, both commercially available and ad-hoc synthesised derivatives (see Supporting
- Information File 1 for the syntheses of derivatives 1k, 1m–s). Encouragingly, all 16 amines were successfully converted to the corresponding 2-aminobenzoxazole derivatives with yields greater than 50%. Beyond piperidine, other cyclic amines, such as morpholine, piperazine, and pyrrolidine, also reacted
- its 5- or 6-substituted derivatives with a variety of cyclic, alkyl and branched secondary amines, probing the protocol’s versatility and confirming its potential usefulness. This study provides the basis for the application of the protocol in continuous flow systems, such as a continuous
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- , two cyclic dimers, designated as compounds 12c and 12d, were isolated, exhibiting strong absorption bands at 493 and 474 nm, high PLQYs of 0.61 and 0.54, and notable CPL activity (|glum| = 0.74 × 10−3 and 1.3 × 10−3, respectively), with corresponding brightness values (BCPL) reaching 19 and 31 M−1 cm
Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles
Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104
- , pyridinyl, furyl, isopropyl, and cyclohexyl substituents were introduced into position 3; cyano and various carbonyl groups were added to position 4 and cyclic amine residues were added to position 5 which increase the solubility of the synthesized compounds 3 (Scheme 2). An analysis of the yields of
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- Peter Gabko Martin Kalnik Maros Bella Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovakia 10.3762/bjoc.21.101 Abstract Oxetanes are 4-membered cyclic monoethers which have found important applications in medicinal chemistry as polar and metabolically
- was generally accepted that this cyclic ether is planar but this myth was eventually debunked by Luger and Buschmann in 1984 who carried out the first X-ray analysis of oxetane [2] and calculated a small puckering angle of 8.7° at 140 K, which is much smaller than the approximate 30° puckering angle
- base [5]. In fact, its hydrogen-bond-accepting ability is even stronger than that of the other 3-, 5- and 6-membered cyclic ethers, as well as the carbonyls of aldehydes, ketones, esters and carbonates [6][7][8]. The only better carbonyl-based hydrogen-bond acceptors are amides, carbamates and ureas [9
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- with dibromide 11 to form cyclic bisphosphonium salt 12, which was then subjected to alkaline hydrolysis. The direct precursor 13 was isolated in 10% yield after two steps and, finally, oxidized to PAH 14 using DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The second approach was inspired by well
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
- ), failed to react effectively. Additionally, the detailed reaction mechanism, explored through control experiments and cyclic voltammetry analysis, revealed a complex series of chemical transformations. The proposed mechanism involves the anodic oxidation of bromide ions to generate molecular Br2, which
- cyclization and deprotonation to yield the desired cyclic product 40, with Umemoto’s reagent serving both as the trifluoromethyl source and the oxidant. In 2023, Li and Fu’s group reported a novel metal-free electrochemical oxidative difluoroethylation method for constructing azaheterocycles, using sodium
- experiments and cyclic voltammetry (CV) indicated that the reaction mechanism proceeds via a radical pathway. DFES-Na undergoes single-electron oxidation at the anode, generating a radical that reacts with the olefinic amide, followed by intramolecular cyclization to form the target difluoroalkylated
Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents
Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97
- estimated from parameters for enamines (N = 10–16), cyclic N,N-ketene acetals (N = 18–20) [11][12] , and the deoxy-Breslow intermediate (N =15.6) [13]. The nucleophilicity of S,N-ketene acetal 4 clearly exceeds that of ethanol (N = 7.4). In addition, triethylamine is more nucleophilic (N = 17.30 in
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- well with the observed reactivities and selectivity. Attempted macrocyclization leading to linear polymers Formyl groups have diverse reactivities and enable facile condensation, dynamic covalent chemistry, and so on. In this work, we tried the synthesis of cyclic oligomers composed of naphthalene
- molecular weights. These results implied that formation of well-defined cyclic oligomers was quite limited. To increase the well-defined species, [4.3.3]_CH2OH was separated into two enantiopure fractions (Supporting Information File 1, Figure S505), one of which was used for the acid-mediated reaction
Gold extraction at the molecular level using α- and β-cyclodextrins
Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89
- together to form cyclic oligosaccharides. The naturally occurring cyclodextrins, also named native cyclodextrins, have typically six (α-CD), seven (β-CD) or eight (γ-CD) ᴅ-glucose units [26][27]. Their monomers are all linked by α-1,4 glycosidic bonds, which results in a molecular geometry with a shape
Supramolecular assembly of hypervalent iodine macrocycles and alkali metals
Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87
- curcumscribe the small cyclic core represented by blue color. Three carbonyl amides project outward. B) DFT image of 1 displaying the distribution of Mulliken charges on iodine (purple), oxygen (red), and carbon (grey); benzyl groups are ommited for clarity. C) Calculated electrostatic potential map showing
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
- and co-workers (2021) utilized oxime chloride and cinnamic acid to synthesize O-acylhydroxamate 68 in good yield (Scheme 23A) [57]. In the presence of a base, oxime chloride was converted to electrophilic nitrile oxide 69 and reacted with carboxylic acid to form the cyclic intermediate 70. On the
- bond of cyclopropenone to give a cyclic intermediate 316 (Scheme 74A) [125]. On the other hand, Wu and co-workers (2022) developed a Pd-catalyzed selective ring-opening of cyclopropenones and vinyl epoxide 318 to give the corresponding esters 319–321 in good yields via a π–allyl palladium intermediate
Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts
Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84
- biocompatibility. The electrochemical properties of such materials have been then evaluated by cyclic voltammetry (CV). For all the properties mentioned above, CDs emerged as low-cost and sustainable photocatalysts. Indeed, upon visible-light irradiation, the generated excited state CD* can operate as either
- four different CDs from citric acid and from blackberries with triarylsulfonium salts. A diffusional rate value was found for all examined nanomaterials (Table 3), pointing to an efficient interaction between the photoexcited CDs and 1b. Cyclic voltammetry experiments have been carried out on both CDs
- product was detected. Conclusion The results arising from cyclic voltammetry analyses, along with the Stern–Volmer fluorescence quenching data and with the isolated products and the GC yields obtained when irradiating the carbon dots in the presence of triarylsulfonium salts, indicate that carbon dots are
Recent total synthesis of natural products leveraging a strategy of enamide cyclization
Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81
- oxidation, the Meinwald rearrangement/aldol reaction gave rise to the bridge cyclic intermediate 35, which can finally be converted into both (−)-fortuneicyclidin A and (−)-fortuneicyclidin B. Polycyclization Cyclization/Pictet–Spengler reaction The hexahydropyrrolo[2,1-a]isoquinoline or tetrahydropyrrolo
Recent advances in controllable/divergent synthesis
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- utilizing in situ-generated π-allylpalladium complexes to capture strained cyclic allene intermediates (Scheme 4) [22]. By modulating the ligands in the reaction system, two distinct polycyclic scaffolds, 13 or 14, could be synthesized with high selectivity. Mechanistically, the Pd(0) catalyst coordinates
- to substrate 11, followed by oxidative addition and release of carbon dioxide to form the zwitterionic π-allylpalladium intermediate Int-21. Under the reaction conditions, silyl triflate 12 undergoes a fluoride-mediated 1,2-elimination to generate the cyclic allene intermediate Int-22. Through a
- , Koenigs, and co-workers demonstrated solvent-controlled bifurcation in the light-driven reactivity of cyclic diazo imides 41 with thiols 42, unveiling two mechanistically distinct pathways (Scheme 11) [40]. In dichloromethane (DCM), the reaction proceeds via a carbene intermediate, enabling cascade C(sp2
Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions
Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72
- metabolism [3][4]; cyclic peptides play critical roles in plant or bacterial defenses and as well as animal hormone signaling [5][6]; cyclic proteins exhibit diverse therapeutic functions [7]; and cyclic nucleotides are essential for molecular cloning and hold potential for disease treatment [8]. In contrast
Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters
Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69
- energy sensitizers, would represent an attractive platform for future reaction design. Here, we disclose the photoactivation of simple alkenylboronic esters established using alkene scrambling as a rapid reaction probe to identify a suitable catalyst and boron motif. Cyclic voltammetry, UV–vis analysis
- detrimental to reactivity leading to substrate degradation. Given the ease of access and enhanced stability of pinacol esters to column chromatography, this motif was advanced for further reaction design. Cyclic voltammetry analysis of 1a indicates that single-electron-transfer processes with the excited
- details). Conclusion In summary, photoactivation of simple alkenylboronic esters was established using alkene scrambling as a rapid reaction probe to determine the catalyst and boron moiety for sensitization. The use of cyclic voltammetry, UV–vis analysis, and control reaction probes support sensitization
Recent advances in the electrochemical synthesis of organophosphorus compounds
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- that when the reaction was carried out in the presence of TEMPO as a radical scavenger, a side product, TEMPO-P(O)R2, was formed (it was confirmed using high-resolution mass spectrometry). The results revealed that the reaction proceeded in a radical pathway (Scheme 1). Based on the cyclic voltammetry
- gave much better results than a graphite plate. The desired product was likely not formed due to the higher oxidation potential of diethyl phosphonate. Cyclic voltammetry experiments confirmed that Cp2Fe is oxidized first due to its lower oxidation potential than other compounds. Moreover, the reaction
- reaction proceeded via anodic indole oxidation, followed by a reaction with trialkyl phosphite to give the corresponding indole phosphonate (Scheme 11). Cyclic voltammetry experiments confirmed that free indole can oxidize at the anode and generate a radical-cation intermediate. Also, no product was
Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones
Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59
- -state structure, two bonds (Ca–O and Si–C) are broken, while a Si–O bond is simultaneously formed, in a concerted step implying a cyclic flow of six electrons in a five-membered ring. The isocyanide Ca–N–C bond angle in TS 11-12 lies between that of 7 and 9. While the replacement step is slow, and hence
Origami with small molecules: exploiting the C–F bond as a conformational tool
Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54
- favourable accommodation of a wider C–C(F2)–C angle within the cyclic product 11. Another illustration of the geometric perturbation caused by the wider C–C(F2)–C angle comes from the stearic acids 12 and 13 (Figure 3); the gem-difluorinated analogue 13 has substantially greater conformational disorder
- interruption of the fluorine pattern means that the C–F dipoles no longer all cancel each other out, and this results in a very high calculated molecular dipole (μ = 7.15 D). Having concluded our survey of linear alkanes, we will now focus on cyclic systems [48]. When fluorine is introduced into a small
- pendant aryl moiety, is better for target-binding and hence 41 is a ≈10-fold more potent inhibitor of BACE-1 than 40. Several further examples of cyclic ethers will be examined in section 5 (sugars). The anomeric effect applies in acyclic ethers, too. Consider the non-fluorinated scaffold, Ph–O–CH3 (42
Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters
Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50
- cyclic amino acids are common structural motifs in the design of small-molecule drugs and peptidomimetics [1]. For example, the clinically used anesthetics carfentanil (1) and remifentanil (2), the FDA-approved antipruritic medication defelikefalin (3), and the arginase inhibitor 4 [2] possess cyclic α,α
- -disubstituted piperidine-containing amino acid subunits. Likewise, a cyano-substituted cyclic aminal is a core structural unit of the fibroblast activation protein inhibitor 5 [3] (Figure 1). The widespread use of non-proteinogenic cyclic amino acids in drug discovery justifies both the design of new analogs
- feature at Ep = 1.78 V vs Ag/Ag+ (100 mV/s scan rate; see Figure 3A), and the electrolysis of pyrrolidine 6a under the optimized anodic decarboxylative cyclization conditions (entry 8, Table 1) afforded cyclic hemiaminal 12a (33% NMR yield), whose structure was proved by NMR experiments (Figure 3B). The
Formaldehyde surrogates in multicomponent reactions
Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45
- -donating or electron-withdrawing groups, work well under these conditions. However, the amine component does not react when primary or aromatic secondary amines are used. It works very well with cyclic or acyclic aliphatic secondary amines, such as piperidine or dibutylamine. In all cases, the yields are
- formation of an aminal intermediate E or the enamine derivative when they tried to obtain it from the reaction of CH2Cl2 and diethylamine in the absence of alkyne under suitable conditions (CuCl, 5 mol %, DBU 1 equiv, CH3CN, 60 °C) [62]. Only in some cases can the reaction of CH2Cl2 and certain cyclic
Vinylogous functionalization of 4-alkylidene-5-aminopyrazoles with methyl trifluoropyruvates
Beilstein J. Org. Chem. 2025, 21, 533–540, doi:10.3762/bjoc.21.41
- starting materials to study the vinylogous functionalization with alkyl trifluoropyruvates. The synthesis of compounds 3 was accomplished by the reaction of cyclic ketones 1 and 5-aminopyrazoles 2 in the presence of acetic acid (Scheme 1) [30][31]. Cyclohexenones 1a–c provided the corresponding products
- 3aa–ca in good yields (47–69%). On the other hand, the reaction with tetrahydro-4H-pyran-4-one (1d) occurred with a significant decrease in yield, dropping to 11%. The yield is also affected by the number of carbon atoms of the starting cyclic ketone 1. In the case of structure 3ea, which involves 2
- -indanone, the decrease in yield is not very pronounced. However, when cyclopentanone (1f) or cycloheptanone (1g) are used, the yields dropped significantly to 5% and 6%, respectively. Next, maintaining cyclohexanone as a cyclic ketone, a series of compounds 3 were synthesized by modifying the 5
Cryptophycin unit B analogues
Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40
- ongoing challenge. Cryptophycins are a class of cyclic depsipeptides renowned for their high cytotoxicity in the picomolar range often combined with efficacy against multidrug-resistant tumour cell lines. However, cryptophycins failed as stand-alone drugs in cancer treatment, and their naturally occurring
- obtained through Grubbs metathesis and subsequent acetonide cleavage in a superior yield of 76%. The finalising steps to obtain epoxides 26 and 2 (Scheme 3) were a diol–epoxide transformation [11][19][32], including firstly the formation of a cyclic orthoester, secondly the formation of a bromohydrin
Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction
Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36
- spectra [1]. Moreover, the ethylene bridge creates a cyclic 8-membered core, inverting the thermodynamically stability in favor of the Z boat conformation compared to parent azobenzene, which has a stable E configuration [1][2][3][4]. Preceding studies including azobenzene-based photopharmacophores showed
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