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Search for "X-ray" in Full Text gives 1307 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
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
- allopyranoses; b) synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose integrating the 2,3-cis, 3,4-cis relationship for the halogens (this work). Direct comparison of 19F resonances of halogenated talose analogues 12–15 (19F NMR; 470 MHz, CDCl3). X-ray analysis of compound 13–15
Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles
Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206
- –11). The stereostructure of the products was confirmed by X-ray crystallographic analysis using the minor diastereomer of 3bd, nicely separated from the major isomer by recrystallization, and the major product 4ba. As was our expectation, these compounds [49] possess the anti relationship between the
- was confirmed as 2,3-anti-3,4-syn by its X-ray crystallographic analysis [49] (Figure 2) whose construction could be readily understood as the result of a highly stereoselective SN2-type epoxy ring opening of 2a, followed by the intramolecular lactone formation with the pro-R ethoxycarbonyl group
Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt
Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204
- donors in recent years. Herein, a new structural motif for this compound class was developed: iodoloisoxazolium salts, bearing a cyclic five-membered iodolium core fused with an isoxazole ring. A derivative of this class was synthesized and investigated in the solid state by X-ray crystallography
Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments
Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202
- corresponding thiones. The yield of reaction products ranges from 42 to 80%. The crystal structures of catechols with 3-nitropyridine or 1,3,4-oxadiazole-2(3H)-thione moieties were established by single-crystal X-ray analysis. The possibility of forming intra- and intermolecular hydrogen bonds has been
- ), HRMS, and elemental analysis. The molecular structures of compounds 5, 6 and 8 in crystal state were determined by single-crystal X-ray analysis. X-ray data The X-ray suitable crystals 5, 6·0.5CH3CN, and 8 were grown by slow recrystallization of the compounds from acetonitrile solutions. The unit cells
- of complexes 5 and 8 do not contain any solvent molecules, while the unit cell of crystals 6·0.5CH3CN contains one acetonitrile molecule per two catechol molecules. The nitro-substituted pyridine group in 5 is disordered in two positions. The X-ray structure of catechol 5 is shown in Figure 1, and
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- enantioselectivities were in the range of 82–97% and were lowest for the prenylation, and highest for Z-geranylboronic acid. The absolute configurations of the products were established by X-ray crystallography of the hydrochloride salts of the corresponding bromoindole and bromodihydroisoquinoline derivatives 20 and
Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system
Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200
- additionally confirmed by X-ray diffraction (see Supporting Information File 1 for details) (Figure 2). To confirm the reaction mechanism, we performed diazotization followed by azo coupling of amide 2a using labeled Na15NO2 as the nitrosating reagent (Scheme 4). As a result, 15N-labeled triazinone 8 was
- physiological conditions. Moreover, the target bicyclic compounds were shown to be thermostable substances and could be used in various fields of materials science. Examples of bioactive compounds containing the 1,2,3-triazin-4-one core. The X-ray structure of compound 1b (CCDC 2363621) and 7h (CCDC 2363622
- . Supporting Information Supporting Information File 96: Experimental procedures, characterization data of all products, copies of 1H, 13C NMR, 15N spectra of new compounds, DSC curves,X-ray crystallographic data and copies of IR spectra. Acknowledgements The crystal structure determination was performed at
Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines
Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198
- proved by X-ray studies. Assuming the mechanism of addition is similar in the case of other nucleophiles, the configuration of others was assigned by analogy. More sterically demanding di-tert-butyl thiomalonate (2) reacted in a similar fashion as the dibenzyl thiomalonate (1), leading also to desired
Synthesis and reactivity of the di(9-anthryl)methyl radical
Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193
- , Supporting Information File 1). ESR and MS measurements as well as X-ray crystallography revealed that the radical species was assigned 10-mesityl-9-anthroyxyl radical (5), obtained in 47% yield (Figure 4c, Figure S8, Supporting Information File 1). Thus, two decomposition pathways were considered: a minor
- ) ESR spectrum of anthroxyl radical 5 (black line, Exp.) and its simulated pattern (red line, Sim.). (b) Hyperfine coupling constant of 5. (c) X-ray structure of 5. Hydrogen atoms are omitted for clarity. Cyclic voltammogram (CV) of DAntM cation. (a) CV measured with scan rate at 3.0 V s−1. (b) Scan
- . Decomposition pathway of the DAntM radical under air conditions. Supporting Information Supporting Information File 81: Synthetic procedure and compound characterization data (1H, 13C NMR, MS, melting point, X-ray crystallography) of new compounds. DFT calculation results and optimized structural Cartesian
Electrochemical allylations in a deep eutectic solvent
Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189
- end, the DES mixture from cycle 3 of Table 8 following product extraction was electrolyzed at 100 mA constant current using glassy carbon electrodes until 2 F/mol of current had passed. This deposited a metal clump on the electrode that was removed and then analyzed using X-ray fluorescent
- using a scoopula for further use and analysis using a Thermo Scientific Niton XL3t X-Ray Fluorescent Spectroscopy analyzer. Product characterization 1-(4-Methoxyphenyl)-3-buten-1-ol [39]: 1H NMR (300 MHz, CDCl3) 7.27 (d, J = 8.58, 2H), 6.86 (d, J = 5.82, 2H), 5.83–5.73 (m, 1H), 5.17–5.10 (m, 2H), 4.67
Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation
Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188
- reaction was expected, Figure 2) with morpholine under previously found conditions (Scheme 2). To our delight, the meta-1,2,4-oxadiazole aniline 3ab, formed by the sequence of aldol-type reactions, was isolated in 80% yield and its structure was confirmed by NMR and single crystal X-ray analysis (CCDC
Natural resorcylic lactones derived from alternariol
Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187
- substituted derivatives Alternariol: Alternariol (AOH, 1, Figure 4) was first isolated in the early 1950ies from Alternaria tenuis (synonymous with A. alternata). Its structure was elucidated with chemical analysis methods [33][54] and later unambiguously confirmed by X-ray crystallographic analyses [55][56
- an X-ray crystallographic analysis [108]. Further syntheses have been presented over the decades including a biomimetic synthesis [68] and a synthesis of deuterated AME [70]. It was isolated from numerous fungal sources, especially from Alternaria spp. (i.e., A. brassicae, capsici-anui, citri
- structure of verrulactone A was later unambiguously confirmed by X-ray crystallographic analysis [160]. Chirality and absolute configurations remained unresolved, where it should be noted that even verrulactones A and B are axially chiral with an assumed significant racemization barrier. At least it has
Computational toolbox for the analysis of protein–glycan interactions
Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180
- needed to deeply investigate the multifaceted aspects of protein–glycan interactions. To date, advanced and versatile NMR, X-ray crystallography, and MS methods [36][37][38] above all, have been developed to reach extensive information on the structural and conformational features of glycans and proteins
- . Several experimental techniques, including NMR, X-ray crystallography and Cryo-EM, can provide critical information for the characterisation of protein structure and conformation. Their widespread and wisely use permitted to experimentally determine the structures of around 200,000 proteins [78], all
Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps
Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178
- methyl esters 144. Subsequently, these esters are converted to various 3-hydroxypyrazoles 143 with hydrazine salts by microwave-assisted cyclization (Scheme 49) [152]. The method tolerates a large number of functional groups. In addition, X-ray structural analysis proved that the products are aromatic 3
Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates
Beilstein J. Org. Chem. 2024, 20, 2016–2023, doi:10.3762/bjoc.20.177
- undergoing yet another diastereoselective 6-endo-trig intramolecular oxa-Michael addition. The structure and stereochemistry of compounds 3 and 4 were confirmed by 1H-1H-COSY and 1H-1H-NOESY NMR experiments. This was further unambiguously established by single crystal X-ray analysis of a representative
- reported in due course. Biologically active derivatives of cyclohexanones. X-ray structure of 4a (CCDC 2351387). Origin of stereoselectivity in the double Michael addition. The Michael donor–acceptor reactivity of curcumin: previous vs present work. A plausible reaction mechanism. Scale-up reaction
Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies
Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176
- azobenzene (Azo) or, more recently, arylazopyrazoles (AAPs), which change shape and polarity on photoisomerisation between the E and Z states, thus changing the self-assembled structure. Small-angle X-ray scattering (SAXS) is a powerful technique to probe the morphology of PS and can be used to measure the
- mechanisms of structural changes using in-situ light irradiation with rapid, time-resolved data collection. However, X-ray irradiation has been shown previously to induce Z-to-E isomerisation of Azo-PS, which can lead to inaccuracies in the measured photostationary state. Here, we investigate the effect of
- light and X-ray irradiation on micelles formed from two different PS, containing either an Azo or AAP photoswitch using SAXS with in-situ light irradiation. The effect of X-ray irradiation on the Z isomer is shown to depend on the photoswitch, solvent, concentration and morphology. We use this to create
Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators
Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172
- toluene (Scheme 1). The reaction smoothly proceeded to afford dialkylated macrocycle 2a in 92% yield. In addition to 2a, monoalkylated product 3a and dipyrrin dimer 4a were obtained as minor products in 4% and 3% yield, respectively. The structure of 2a was unambiguously confirmed by single-crystal X-ray
- governed the regioselectivity. Reactivities of norcorroles with various reagents. Top and side views of the X-ray structures of a) 2a and b) 1 [2]. Mesityl groups and hydrogen atoms were omitted for clarity. Thermal ellipsoids are drawn at 50% probability. UV–vis–NIR absorption spectra of 1 and 2a in
Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations
Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170
- Scheme 1 compound 6 was treated with isopropyl iodide (7) in DMF in the presence of sodium hydride to provide products 8 and 9 in 38% and 46% yields, respectively. The structures of both compounds were unambiguously assigned using X-ray crystallography and 1H and nuclear Overhauser effect (NOE) NMR
- Texas A&M University for X-ray diffraction analysis. Funding All studies were funded by BioCryst Pharmaceuticals Inc. Conflict of Interest The authors declare the following competing financial interest(s): All authors are employees/former employees of BioCryst Pharmaceuticals Inc. and may hold stock in
Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles
Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164
- two diastereomers, lying in the intervals 5.5–6.0 Hz and 1.5–2.5 Hz for the cis and trans forms, respectively [33][34]. This makes it easy to assign the stereochemistry of the products obtained. Additional confirmation was gained from X-ray analysis data for structure 3t (Scheme 2). In some cases, we
- information, X-ray crystallographic data, synthetic procedures, analytical data and NMR spectra for the reported compounds. Acknowledgements We thank the Research Center for Magnetic Resonance, the Center for Chemical Analysis and Materials Research, and the Center for X-ray Diffraction Methods of Saint
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
Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides
Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157
- (1–3 % spectroscopic yield) when BF3·OEt2 was added to the reaction mixture. X-ray crystallography and DFT calculations The solid-state structure of difluoroiodane 6 is shown in Figure 2 and displays the expected square pyramidal geometry around the iodine atom, with only minor distortion (τ5 = 0.191
- Supporting Information File 1). DFT calculations were carried out to gain further insight into the structures of iodine(V) fluorides 21 and 22 whose X-ray structures could not be obtained, and hypothetical iodine(V) amides 7a and 7b which could not be made. Comparisons were made with iodine(V) compounds 6
Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations
Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156
- reaction step for the synthesis and purification of the starting azomethines 9, we cannot propose the Ugi-3CR approach as more suitable compared to the Ugi-4CR approach. The structure of the Ugi bisamides 5–8 were proved by X-ray diffraction study on the example of substance 8c (Figure 2), according to
- conventional thermal heating, amide 10a was isolated, albeit in a lower yield and accompanied with tar formation. In addition to the 1H, 13C NMR spectra and mass spectrometry data, the structure of compound 10d was established by X-ray diffraction analysis (Figure 3). It was also found that the substituents at
- case of bisamides 5d, 6a, 6c, 7b, 8a, and 8c (Table 2), additional transformation products were also isolated from the reaction mixture. According to 1H and 13C NMR, MS, and X-ray diffraction studies these were the corresponding ketobisamides 12, which are products of a nucleophilic substitution of the
Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides
Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155
- cyclic imides. The solid-state structures of the N-phenyl derivatives, determined by X-ray crystallography, reveal changes in packing preference based on the number of aromatic rings in the core. The optical and electronic properties of the title compounds compare favorably with other previously
- evaporation of CH2Cl2/MeOH solutions and characterized by X-ray crystallography. 7-Ph crystallizes in the Pbcn space group into a solvent superstructure of π-stacked columns of 7-Ph. The imide groups are pointed in alternating directions within a stack. While this may occur in part as a consequence of the
- -Ph as determined by X-ray crystallography. Representative C=O···H–C and C–H···π interactions are indicated in teal and magenta, respectively. Top-down views of π-stacking modes in c) 7-Ph and d, e) 8-Ph. Hydrogen atoms have been removed for clarity in c–e. Atom color code: C = tan, H = white, Cl
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
- single diastereomer (Scheme 5, Table 3), while N-phenylglycine afforded the enamine derivative 10 (Scheme 6, Table 4). Both structures were confirmed by single-crystal X-ray diffraction of compounds 9a and 10a (Figure 2). The diastereoselectivity observed in the hemiaminals and their stability can be
- further confirmed by single-crystal X-ray diffraction of compound 12c (Figure 3). Conclusion In this work, we have demonstrated the straightforward access to a variety of complex nitrogen heterocycles by using unprotected deactivated amines tethered to carboxylic acids combined with arylglyoxals in the
- functional group in the resulting Ugi adduct can be exploited in different post-condensation strategies to generate multiple fused nitrogen heterocycles in an easy manner. Fused heterocycles containing the piperazine and diazepine core. X-ray diffraction structures of pyrrolopiperazinones 9a (left) and 10a
Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations
Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151
- subsequently overexpressed in insect cells and purified as soluble proteins, culminating in the elucidation of the X-ray crystallographic structure of MaDA (Scheme 5B, PDB: 6JQH). With these key enzymes in hand, Lei and co-workers conducted a chemo-enzymatic total synthesis of 3 and related natural products
- the Diels–Alder reactions (Scheme 6B). Notably, MaDA-3 exhibited high exo-selectivity (original MaDA: endo-selective) and enabled the enantioselective rapid total synthesis of guangsangon J (60) and mongolicin F (61), which are epimers of 58 and 3, respectively. Comparative analysis of the X-ray
- total synthesis of 3 utilizing an identified Diels–Alderase, MaDA. (A) Chemo-enzymatically synthesized natural products by using the originally identified MaDA. (B) MaDA homologue enzyme MaDA-3: X-ray crystal structure and synthesized natural products by leveraging this enzyme. Proposed biosynthetic
Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds
Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142
- revealed by X-ray diffraction analysis. Upon visible-light irradiation, significant transformations of the DA geometry enabled transformations of the supramolecular assemblies on a microscopic scale, subsequently disassembling macroscopic soft scaffolds of DAs. The current work shows promising use for the
- investigated with through-view wide-angle X-ray diffraction (WAXD). The 2D WAXD image of the macroscopic soft scaffold of DA11 showed a diffraction ring in the region of q = 0.5–5.0 nm−1 (Figure 4c), which was similar to that of DA10 [37]. A low degree of angular dependency was observed in the macroscopic soft
- Rigaku NANOPIX equipped with a HyPix-6000 (Rigaku) detector. The scattering vector (q = 4⋅π⋅sin(θ)/λ), scattering angle θ, and the position of the incident X-ray beam on the detectors were calibrated using several orders of layer reflections from silver behenate (d = 58.380 Å), where λ refers to the
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