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Search for "structure" in Full Text gives 2877 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer
Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119
- largest cyclic array in the series. The oxidative fusion reaction with [bis(trifluoroacetoxy)iodo]benzene (PIFA) afforded a cyclophane-type aza[5]helicene-incorporated macrocycle, the structure of which was unambiguously revealed by X-ray diffraction analysis. Its optical properties have been investigated
- 1) [6][7][8][9][10][11][12]. Nevertheless, partially fused macrocyclic intermediates are also important as they exhibit structural strain associated with both the polycyclic segments and the inherent strain stemming from the macrocyclic structure. For instance, cyclic chrysenylenes [13][14][15][16
- an aza[5]helicene-incorporated macrocycle. The resulting cyclophane-like structure and its optical properties have been analyzed in detail. Results and Discussion Synthesis and characterization Synthesis We obtained o-phenylene-pyrrole-thiophene hybrid icosamer 4 during our attempt to synthesize
Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins
Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118
- bioactive fragments into a single molecule through a spacer. An alternative strategy of combining heterocyclic pharmacophores is to incorporate them into a spiro-jointed structure that lacks any intermediate link between the active parts [17]. Despite the fact that these strategies share numerous
- form two new carbon–heteroatom bonds in a 1,2,4-oxadiazoline ring through both variants of orbital overlap. It should be noted that, in this case, NMR spectroscopy is not applicable to assign the product structure due to the presence of only quaternary carbon atoms in the tetrasubstituted 1,2,4
- -oxadiazolines [40]. Therefore, single crystal X-ray diffraction analysis is typically used to confirm the structure, as we have applied for the hydantoin/1,2,4-oxadiazoline spiro-compounds 5k (CCDC 2432465) and 5l (CCDC 2432466) (for details see Supporting Information File 1). The effect of the substituents on
Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent CyreneTM under one-pot conditions
Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117
- -triazoles in CyreneTM (Figure 4). It was shown that the protocol resulted in the formation of products 3a and 5b–f with yields of 57–91% depending on the structure of the bromide derivatives. The isolated yields were in the same range as reported by Citarella et al. [39]. The presence of a terminal carbon
- –carbon double bond in a certain molecular structure could allow for efficient subsequent functionalization via, for example, an addition reaction, opening possibilities for building even more complex molecular skeletons involving 1,2,3-triazole units. Using allyl bromide in the reaction sequence results
General method for the synthesis of enaminones via photocatalysis
Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116
- components of drug derivative formulations, present in more than 7,000 active pharmaceutical compounds [43], the possibility of introducing a pyridine ring into the enaminone structure could be useful for the development of new drug candidates. When pyrrolidine was used as amine reagent, the target enaminone
Azobenzene protonation as a tool for temperature sensing
Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115
- other transformations that can offer useful functionalities. These include ionization via protonation of one of the nitrogens forming the azo bond [12][13], azo–hydrazone tautomerization [14][15], and binding of analytes to side groups [16]. Such transformations depend on the azobenzene structure but
- complexes between 1–3 and MSA (X-MSA and X-(MSA)2, X = 1, 2 or 3). The geometry-optimized structure of 3H+MSA−MSA is shown in Figure 3. In this structure, the second MSA molecule does not bind directly to the azo group but forms a hydrogen bond with the mesylate anion, and one of its oxygen atoms interacts
- to account for the implicit solvation. Frequency calculations were performed for geometry-optimized structures to ensure that the structure was a true minimum energy structure (i.e., no imaginary frequencies). The molecular structures were visualized with ChemCraft version 1.8 (http
Calcium waste as a catalyst in the transesterification for demanding esters: scalability perspective
Beilstein J. Org. Chem. 2025, 21, 1520–1527, doi:10.3762/bjoc.21.114
- of δ-valerolactone (4e) successfully led to the opening of the ring structure of the lactone and the formation of methyl 5-hydroxypentanoate (5e) in 91% yield at a catalyst loading of 1 wt % and for 3 h. The transesterification of triglycerides obtained from the esterification of linear saturated C5
Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones
Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113
- products formed via S–H and N–H insertion reactions should also be tested. This method of modification of the structure of enolizable 5-mercapto-1H-tetrazole has not yet been described. Results and Discussion New precursors 2c,d of sterically crowded thiocarbonyl S-methanides 1c,d Based on the well
- , the quality of the X-ray measurements and structure determination meets all high standards for reliable data. The same applies to the crystal data of 10i, even though its crystal structure contains four independent molecules per unit cell. These molecules exhibit slight differences in their geometry
- , ensuring that no additional symmetry elements were omitted during structure refinement. The obtained data undoubtedly confirmed the anticipated structures and their experimental characterizations. Thioaminal 9i and dithioacetal 10i differ significantly in the substitution of the tetrazole ring. This
Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112
- originating from a hexagonal type of lattice. To further understand the microscopic structure of the assembly, we have performed STM experiments on ultra-thin films of FNAAP. Figure 3a,b shows constant current STM topographs of ultra-thin films of an FNAAP adlayer on HOPG (0001) at different resolutions
- voltage, which is ≈1.1 V. This suggests that while switching, the molecules may not be in their neutral state. Since the graphite–molecule interaction is weak and van der Waals-type, we use the gas-phase calculations and no major change in the electronic structure is expected for molecules upon adsorption
- number, letter, etc. Depending on the state of the adjacent molecules in an array, one can assign a combination of states to address number, letters etc. Thus, in an array of 8 molecules, 88 permutations are possible. Conclusion We have investigated the microscopic structure and electron/hole-induced
Wittig reaction of cyclobisbiphenylenecarbonyl
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- formation between carbonyl and alkene units. Keywords: bathtub; chirality; cyclobisbiphenylenecarbonyl; figure-eight; Wittig reaction; Introduction Figure-eight π-conjugated molecules represent chiral macrocycles with a twisted crossover structure [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15
- ]. Various figure-eight π-systems including aromatic hydrocarbons, belt-type extended π-systems, and porphyrinoids have been reported. The structural twisting in figure-eight macrocycles leads to cross-linked conjugation at the molecular center and a highly symmetric chiral structure with D2-symmetry
- stable figure-eight conformation A to a metastable bathtub conformation B with a small energy difference of approximately 2 kcal mol–1 [21]. In this paper, we discuss the effect of the transformation of the carbonyl groups on the conformational change of the figure-eight structure. We thus intentionally
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
- helicenes. Particular attention is given to multi-heteroatom systems co-doped with elements such as boron, oxygen, sulfur, and selenium, highlighting their influence on CPL performance and structure–property relationships. We classify the nitrogen-doped helicenes into only N-containing helicenes, B,N
Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds
Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105
- substitution in 7-OH quinoline, where the most of the requirements for clean switching are achieved if the K tautomer is considered as off-state and the E one as on-state. Experimental Synthesis and structure elucidation Materials The starting reagents and solvents were purchased from Sigma-Aldrich and
- M06-2X [96][97] functional with the TZVP [98] basis set was used for the structure optimizations in the ground state. The use of M06-2X provides very good predictability in the ground state [51][53][99][100][101][102][103] of the tautomeric composition in tautomeric compounds and proton cranes as well
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
- analogy with an aza-Michael reaction first with the addition of iminoiodinane accompanied with reorganization of double bonds including attack of the negatively charged sulfur atom on nitrogen with subsequent elimination of iodobenzene as good leaving group. The diversity of the structure of the target
- 2,3-dihydro-1,2-thiazole ring are in the range of 75.3–72.4 ppm and signals of the carbon atom of the cyano group in the range of 117.7–116.6 ppm. The structure of 2,3-dihydro-1,2-thiazole 3aa was additionally confirmed by single crystal X-ray diffraction (Figure 2). According to the X-ray diffraction
- (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
N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B
Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103
- human system. In this study, we isolated two previously undescribed N-salicyl-amino acids as natural products (1 and 2) and other two new derivatives (3 and 4) from the organic extract of a culture broth in a modified starch–glucose–glycerol (SGG) medium of Pseudomonas sp. UIAU-6B. The structure of the
- to C-10 showing the presence of the carboxyl functionality of the threonine moiety. Based on this conclusion, the structure of 1 was elucidated and named pseudomonin D. Compound 2 was obtained as a reddish oil, and the molecular formula deduced as C16H20N4O4 (Δ: +0.4 ppm, calcd. for C16H21N4O4
- Supporting Information File 1, Figure S16) confirming that both of these protons were present on the same side of the double bond. The structure of 3 was confirmed using mass spectrometry, 1D and 2D NMR data as a new compound, named pseudomonin F. Compound 4 was isolated as a pink oil. The negative mode
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- substrate scope revealed that the reaction stereoselectivity is highly dependent on the structure of the ketoester component and tends to be unpredictable. 1.3.2 Formal cycloadditions: These stepwise processes typically take place between an enolate or enol ether and a carbonyl under Lewis acid or base
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
- ], medicine [3], sensing [4] and energy storage [5]. Typically, bulk graphene is obtained using a top-down approach, where graphite is exfoliated using chemical or mechanical methods [6][7]. However, this method does not provide precise control over the structure of graphene and graphenoid materials, which is
- crucial for fine-tuning their properties. An alternative is the bottom-up approach where various nanographenes are synthesized form smaller building blocks via classical organic synthesis. This strategy enables precise control over the structure and topology, leading to the development of a vast array of
- benzenoid nanographenes, also known as polycyclic aromatic hydrocarbons (PAHs) [8][9]. PAHs can be considered molecular models of bulk graphene, offering invaluable insights into structure–property relationships in graphene and graphene-based materials. Structural defects appear to be inevitable in real
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- % probably owing to the network structure. By contrast, soluble [3.3.3]_oligo and [3.3.3]_linear had relatively high T90 of 528–532 °C and CY of 68–76 wt %. The high values were ascribed to two unsubstituted naphthalene rings in precursor [3.3.3]_CH2OH, which caused facile branching in the reaction or
Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups
Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94
- structure on the potential energy surface is located, which can be done straightforwardly using standard optimization algorithms. While the use of intermediate energies provides a computationally efficient alternative to explicit transition state searches, it rests on the assumption that there is a
- the transition state [10][11]. The site with the lowest reaction energy is expected to correspond to the experimentally observed reaction site. Therefore, instead of locating the structure of the transition state, the preceding palladacycle intermediate structure is generated and optimized, as shown
- carbon at the reaction site and to the heteroatom of the directing group, as illustrated in Figure 5. To assess the geometry of these complexes, we generate a 2D structure using RDKit, where all atoms are constrained to lie in a single plane. Although this type of 2D embedding is typically used only for
A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones
Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92
- , Supporting Information File 1), but it was not stable enough for isolation. The structure of 8a was confirmed by single crystal X-ray diffraction analysis. The optimized reaction conditions were used to evaluate the substrate scope of the synthesis of imidazopyridine-fused isoquinolinones 8 (Scheme 3). The
- the dienophile presents a negative charge (−0.280 to −0.325, 6a), (−0.280 to −0.327, 6h) and (−0.280 to −0.327, 6r), respectively. This structure induces electrostatic repulsion instead of the requisite attraction for a successful interaction between the electron-rich diene and the electron-deficient
- detected by LC–MS from the reaction mixture. The X-ray structure of 6t indicated that the diene and dienophile are perpendicular to each other which prevents them from being properly aligned for the IMDA reaction. The transition state of the IMDA is electronically destabilized by the sulfur group of the
Synthetic approach to borrelidin fragments: focus on key intermediates
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- a cancer therapeutic, exhibiting anti-inflammatory, anti-angiogenic, antimicrobial, antifungal, and antimalarial activities. While Keller-Schierlein first determined its chemical structure, Anderson later confirmed its absolute configuration using X-ray crystallography [16]. During the screening of
- complex structure, remains an attractive target for synthetic organic chemists worldwide. Several comprehensive reviews on borrelidin have been published, with a strong focus on its synthesis. The first notable comparison of total synthesis methods was conducted by Ōmura in 2005 [48], highlighting four
- LiAlH4 in ether to form alcohol 40 (89%) (Scheme 3). The primary alcohol 40 was then converted to its iodide derivative 42 (89%), from which single crystals were obtained, and its structure was determined unequivocally by XRD crystallography. Iodide 42 was then reacted with sodium phenylsulfinate in DMF
Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold
Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90
- HMBC spectrum of 2 allowed unambiguous assignment of the amine substitution at C-8 with the amine proton (δH 8.30) showing strong HMBC correlations into the triazolopyrazine scaffold [δC 147.9 (C-8), 139.7 (C-9)]. 2D NMR correlations used to characterise the structure of 2 are shown in Figure 2, along
- with relevant position numbering. Crystals obtained for 2 were analysed by X-ray crystallographic studies and confirmed the NMR-based structure assignment. The crystal structure of 2 is shown as a thermal ellipsoid plot below (Figure 3). With a simplified approach for the synthesis of aminated
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
- stripping from activated carbon using α-cyclodextrin. J. Am. Chem. Soc. 2021, 143, 1984–1992. Copyright 2020 American Chemical Society. This content is not subject to CC BY 4.0. Solid-state structure of the complex 2β-CD·HAuBr4·DBC. (a) Capped-stick and space-filling representation of different views of 2β
A versatile route towards 6-arylpipecolic acids
Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88
- . It contains a six-membered ring and is, like its five-membered correlate, known for its secondary structure inducing properties, which are particularly useful in the design of peptide conformations. We present a new and improved way to generate enantiomerically pure pipecolic acid derivatives with
- structure of pipecolic acid is rather challenging and often necessitates early-stage derivatization followed by the formation of the six-membered ring [29][30][31][32]. An alternative is to utilise derivatization reactions such as Suzuki–Miyaura [33] or Sonogashira–Hagihara [34] cross-coupling reactions on
- the Sonogashira–Hagihara cross-coupling products [35]. Furthermore, an in-depth NMR analysis was conducted on the resulting constraints leading to conformational structure predictions. ᴅ-2-Aminoadipic acid (1) [36], a side product formed in the pharmaceutical semisynthesis of 7-aminocephalosporanic
Supramolecular assembly of hypervalent iodine macrocycles and alkali metals
Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87
- pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen–lithium–oxygen bond angle is approximately 98.83
- durability, low harmful, and convenient alternative to heavy-metal reagents [10][11]. Hypervalent iodine compounds exist as trivalent (λ3-iodanes) or pentavalent (λ5-iodanes) species. The λ3-iodanes have an T-shaped structure [12], with the energetically preferred arrangement of the two most electronegative
- projecting outward denoted by an asterisk. Furthermore, the resulting crystal structure reveals that 1 is also a distorted planar macrocyclic system consisting of the amino acids carbonyl oxygens facing inside the ring. All three benzyl groups are located above a single plane (more figures are provided in
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
- ; the first one involves the direct carbonization (at 200–400 °C) of the precursor material for 24–100 hours under solvent-free conditions. The obtained carbon nanomaterials exhibit predominantly a graphitic core structure. In contrast, under hydrothermal conditions, the starting substrates were
- dissolved or suspended in water, and the resulting mixture transferred to an autoclave and treated at a temperature ranging 140–200 °C; the treatment yields CDs with an amorphous structure. The synthetic procedure, as well as the structural and morphological characteristics of these materials, have been
- previously reported by the research group of M. Selva and A. Perosa (see also Supporting Information File 1 for further details) [30][31][32][33][34][35]. As shown in Table 1, the materials synthesized via pyrolysis exhibit a graphitic core, characterized by an ordered structure, whereas those synthesized
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
- , lycopodine features a characteristic tetracyclic structure with a bridged cyclohexanone. To address the challenges associated with constructing the complex ring systems of this structure, She and co-workers devised an intramolecular aza-Prins cyclization strategy to form both the bridge ring and the N-hetero
- [2,1-a]isoquinolin-3(2H)-one framework is a pivotal core structure among various pyrrolo[2,1-a]isoquinoline alkaloids, exemplified by (+)-crispine, annosqualine, and erysotramidine, among others (Scheme 5) [29]. These bioactive alkaloids exhibit a broad spectrum of biological activities, including
- notable example is (−)-cephalocyclidin A, a cytotoxic pentacyclic cephalotaxus alkaloid [33][34]. Although the molecular structure contains a benzo-bridge ring system, disconnection of this bridge reveals a critical tricyclic N-heterocycle. To efficiently synthesize this tricycle, polycyclization of
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