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Search for "conformation" in Full Text gives 765 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions
Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246
- -fluorinated analogs [38]. It is anticipated that the introduction of a CF2 could eventually stabilize the conformation of the six-membered ring via stereolectronic interactions of the CF σ* orbitals with the neighboring CH σ orbital [40]. The 180° FCCH dihedral would rigidify the six-membered ring. We present
The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives
Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244
- single-crystal X-ray analysis were obtained by slow evaporation of a dichloromethane/isopropanol solution of 3b. The crystal structure of 3b, displayed in Figure 4, shows a very similar twisted conformation of the core of the molecule to that of the related methoxy-substituted structure obtained from
- dihydroxyviolanthrone. Chemical structures of 2b and 3b. Optimised ground state geometries of compounds 2 and 3 calculated using B3LYP/6-311G(d,p) in the gas phase. Views of the crystal structure of 3b (left, shows displacement ellipsoids drawn at 50% probability level, right showing the twisted conformation
N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity
Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240
- (4a) initially resulted in the glycosylation of the oxygen atom to give intermediate A (−20 °C, 1.5 h). Extension of the reaction time (20 °C, 12 h) afforded N-indigoglycoside 5a which was isolated in 35% yield. The product contained an α-rhamnosyl moiety with 4C1 conformation. The formation of the
Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines
Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236
- inhibitor conformation found by docking is energetically unfavorable and therefore the expected activity of compound 5e will be much lower than that of compounds 4a–e. Molecular docking data can therefore be used to infer the structure–activity relationship. The substituent on the C-5 atom of
C–C Coupling in sterically demanding porphyrin environments
Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234
- were determined. All structures were investigated using the NSD method [8][9], which allows a quantification and visualization of distortion modes. It can be observed from the crystal structures that the porphyrins’ rings all exhibit the typical saddle-shaped conformation. Interestingly, substitution
Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study
Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221
- (Figure 1): (1) facing inward into the cavity, which creates a belt of hydrogen bonds (the so-called “head–tail” arrangement, “closed” conformation). Notably, in this way, the size of the cavity vestibule is significantly reduced and in the second way (2) they are directed outside the cavity, thus
- G09 package. The PyMOL software was used to create molecular graphics images [32]. Chemical structure of γ-CD (A); M062X/6-31G(d,p) optimized conformers of nonhydrated γ-CD in two projections – side view (B) and top view from O6 side of the truncated cone (C). The "closed" conformation is with
Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels
Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220
HFIP as a versatile solvent in resorcin[n]arene synthesis
Beilstein J. Org. Chem. 2024, 20, 2469–2475, doi:10.3762/bjoc.20.211
- -shaped conformation it precipitates out of solution acting as a thermodynamic sink [5][6]. Shortly after, Cram et al. recognized the potential of resorcin[n]arenes as compounds large enough to encapsulate other simple molecules or ions and group them with other known macrocyclic arene compounds, e.g
- , chlorinated species 1h and 1i, and carboxylic acid-containing 1s, developed high quality crystals from standing solutions in dimethyl sulfoxide for 1h and 1i, and methanol for 1s. Their molecular crystal structures were determined and are shown in Figure 1b displaying the classic cone conformation for both
Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose
Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208
- and nonbonding interactions for the halogen at C4. Finally, density functional theory (DFT) calculations corroborate the preference of talose analogues to adopt a 4C1-like conformation and a natural bonding orbital (NBO) analysis demonstrates the effects of hyperconjugation from C–F antibonding
- orbitals. Keywords: organofluorine; pyran inter-halide; solid-state conformation; solution-state conformation; Introduction Polyfluorinated pyran analogues of carbohydrates have attracted attention over the years. This class of glycomimetics has great biological potential with useful applications [1][2
- ][25][26][27][28][29][30], such as the solution-state conformation of diastereomeric polyfluorohexitols [31]. Herein, we report the synthesis of pyran inter-halide analogues of ᴅ-talopyranose 6, integrating also the 2,3-cis, 3,4-cis relationship for the halogens, from known intermediate 5 (Figure 1b
Phenylseleno trifluoromethoxylation of alkenes
Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207
- ], electronic effects [17][18], and conformation [19][20][21]. Some trifluoromethoxylated molecules can be used as drugs in the treatment of various pathologies (Figure 1) [22][23][24][25][26][27][28][29]. On the other hand, despite its toxicity at higher doses, selenium is also an essential trace element in
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- -methylcrotylsilane (product 52) and disubstituted cyclic silanes (such as the silane, leading to 53), locked in syn-conformation. For the 2,3-disubstituted allylation products such as 52 and 53, the diastereomeric ratio spanned across 18:1 to >50:1. Notably, all 2,3-disubstituted silanes required an increased
Factors influencing the performance of organocatalysts immobilised on solid supports: A review
Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183
- catalyst closer to the support, impacting electronic properties and ligand conformation. With large catalyst molecules, the pores of an ordered mesoporous material being similar in size to the catalyst can create significant diffusion barriers as the catalyst attempts to enter the pores. As a result, the
- covalent bonding. These adsorptive interactions can alter the electronic properties and conformation of the supported organocatalyst, thereby influencing its catalytic activity compared to its homogeneous counterpart. For instance, Fotaras et al. showed that the incorporation of a tripeptide-like
Computational toolbox for the analysis of protein–glycan interactions
Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180
- , depending on the values adopted by the torsional angles around the glycosidic linkages [10]. The high variability of linkages type, branching, stoichiometry, anomeric configuration (alpha and beta), and conformation contributes to the intricate nature of glycans. The complexity of the glycome is even higher
- only by their chemical composition but also by their conformation. As mentioned above, glycans are characterised by a huge conformational diversity (see Figure 1): even individual furanoid or pyranoid monosaccharides can assume various shapes and in longer glycans the relative orientation of the
- design and discovery providing access to physics-based molecular modelling tools and machine learning technologies from a single modelling environment, however, it is not free-accessible. Further valuable insights into the structure and conformation of saccharides, determined by experiment and simulation
Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies
Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176
- ) that contains mostly Z isomers. This can be reversed using blue light or heat in a process that is stable over many cycles [7]. Isomerisation of azobenzene leads to a change in its conformation and polarity which, when combined into a surfactant molecule, modifies the resulting molecular geometry and
- . It should be noted that a lag between the time taken to reach the PSS and the time for the new micelle morphology to form is expected. This is due to the additional time that is required for diffusion and reassembly of the AzoTAB in the Z conformation into the new equilibrium structure [22]. The
- , Supporting Information File 1). This morphology change can be attributed to two changes in the AAPTAB on E–Z isomerisation [19]. Firstly, the shape change of the AAPTAB to the bent, “T-shape” conformation prevents the π–π stacking which was previously possible in the more planar, E isomers that were arranged
The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)
Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162
Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles
Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154
- assayed in our group. Under these conditions, the bis-1,4-benzodiazepines 7 resulting from the reaction of the amino group with the imine on the benzodiazepine were obtained as a single diastereomer. On the basis of the preferred conformation for the 1,4-benzodiazepin-5-ones 5 and 6 [20][22], where the
- amide substituent in C3 is pseudoaxially oriented in an all-trans conformation, only the unlike attack would be allowed (Scheme 3). On the other hand, when 3-bromopropanamine was used, the formation of the pyrrolobenzodiazepinone system 8 was observed albeit along with benzodiazepinone 5c (Scheme 4). In
Ring opening of photogenerated azetidinols as a strategy for the synthesis of aminodioxolanes
Beilstein J. Org. Chem. 2024, 20, 1671–1676, doi:10.3762/bjoc.20.148
- ). The corresponding protecting group (PG) was thought to control the conformation of the 1,4-biradical 2, which is known to be important for efficient Norrish–Yang cyclizations [27][28]. Furthermore, the PG was deemed crucial for the development of further functionalizations of the azetidinols (vide
- effect on product formation, potentially by changing the substrate’s conformation. Ring opening Based on its outstanding performance in the photoreaction, we selected Ts-protected azetidinol 3a as our preferred substrate to test ring-opening reactions. However, initial attempts were met with limited
Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry
Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147
- its β-helical structure; reversion of the N-methylation led to complete conformation loss. The methylated asparagine residues at positions 16, 22, and 28 form an intramolecular chain of hydrogen bonds along the outside of the β-helix. Hydrogen atoms from the amide methyl group form hydrogen bonds with
Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines
Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140
- conformational stability of proline-rich proteins such as collagen [2]. Therefore, pyrrolidine derivatives are particularly susceptible to conformational control induced by a fluorine substituent. The 5-membered pyrrolidine ring is a cyclic alkylamine that adopts a conformation that resembles the familiar
- fluorine gauche effect, commonly observed in compounds containing the F‒C‒C‒X fragment (where X is an electron-withdrawing substituent, such as nitrogen), typically favors a conformation where F and X are gauche to each other. This preference is attributed to stabilizing σCH→σ*CF and σCH→σ*CX
- interactions [4]. Protonation of 3-fluoropyrrolidine generates the 3-fluoropyrrolidinium cation, and this typically results in a highly favored conformation in both the gas phase and solution where the fluorine and nitrogen atoms are cis, mirroring the behavior observed in analagous 4- and 6-membered ring
Mining raw plant transcriptomic data for new cyclopeptide alkaloids
Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138
- the β-carbon of leucine ether linkage. Structurally related cyclopeptide alkaloids have similar J-values (Jα-β ≈ 8.0 Hz) and have been assigned as ʟ-erythro (anti) conformation [20][39]. Metabolomic analysis and GNPS networking Live samples of C. americanus and G. jasminoides were separated into
Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA
Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132
- /off or from low to high. This strategy can be used for specific targeting or local drug activation to reduce its toxicity [14]. There is an increasing use of the photoisomerization to control the conformation as well as the activities of various biomolecules with the development of photopharmacology
- the known crystal structure. The extended E-isomer establishes contact through galactoside and the first aryl ring only, while the bent Z-isomer has proper conformation to wrap around the central His53 residue and to establish a more extended interaction with the protein surface. This would be in
- LecA binding by light. Few differences were observed for the meta- (2 and 4) and ortho-substituted azobenzenes (5). Thermodynamics contributions exhibit larger variations with stronger enthalpy of binding for the Z-isomer, probably in relation with a folded conformation generating additional contact
Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement
Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129
- compounds by changing their metabolic stability, hydrogen bonding ability, lipophilicity, solubility, bioavailability, conformation and general structure [1][2][3][4]. About 20% of commercially available drugs contain fluorine, and this ratio is estimated to increase further [5][6]. Among organofluorines
Synthesis of cyclic β-1,6-oligosaccharides from glucosamine monomers by electrochemical polyglycosylation
Beilstein J. Org. Chem. 2024, 20, 1421–1427, doi:10.3762/bjoc.20.124
- disaccharide 16 was obtained as an exclusive product. The optimized structure of 15 calculated by DFT (B3LYP/6-31G(d)) suggested that the pyran ring preferred the boat conformation because the chair conformation of the pyran ring was controlled by the introduction of the 2,3-oxazolidinone protecting group (see
Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes
Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115
- . Scaffold exploration of the eunicellane skeleton During protonation-induced cyclization of 1 and 2, the C6–C7 alkene showed higher nucleophilicity than either of the other two double bonds likely due to the unique conformation of the eunicellane skeleton. This selective reactivity was further supported
Sustainable tandem acylation/Diels–Alder reaction toward versatile tricyclic epoxyisoindole-7-carboxylic acids in renewable green solvents
Beilstein J. Org. Chem. 2024, 20, 1308–1319, doi:10.3762/bjoc.20.114
- in a much shorter time (Table 1, entry 4) when the temperature of the reaction medium was increased to 50 °C. According to X-ray and Raman spectroscopy techniques, triglyceride molecules in liquid form are arranged in a dynamic chain-like conformation [114][115][116]. As the temperature of the
- in good agreement with those reported for this compound in the literature. In all synthesized compounds, Ha and Hb protons are only in endo conformation and therefore the amide and carboxylic acid functional groups are arranged in exo conformation. The fact that the flexible 2n and 2o compounds in
- reaction medium has been previously demonstrated by 1H NMR studies [129]. The elongation of the alkyl chain attached to the N atom facilitates the formation of the epoxyisoindole product by favoring the s-cis conformation due to steric factors (Thorpe–Ingold effect) [130][131]. Briefly, in this type of
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