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Search for "X-ray crystallography" in Full Text gives 307 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of a novel category of pseudo-peptides using an Ugi three-component reaction of levulinic acid as bifunctional substrate, amines, and amino acid-based isocyanides
Beilstein J. Org. Chem. 2019, 15, 852–857, doi:10.3762/bjoc.15.82
- transfer from oxygen to nitrogen (Mumm rearrangement) in D which completes the Ugi reaction accompanied by formation of the corresponding bis-amides. The structure of products was confirmed by IR, 1H and 13C NMR, CHN and HRMS analyses and by X-ray crystallography for 4a. The IR spectra of the derivatives
Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands
Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81
- , SQUID magnetometry and X-ray crystallography is reported herein. Preliminary results concerning the photoisomerization of compound 1 are reported as well. Results and Discussion Synthesis of ligands and metal complexes Scheme 1 shows the synthetic procedures. The yellow-orange colored zinc complexes (3
- assigned with the aid of APT, HSQC, HMBC and COSY spectra. The 13C NMR spectrum of complex 6 is also in agreement with C2v symmetry revealing only 11 signals (seven for the aliphatic and four for the aromatic carbon atoms) for the 38 carbon atoms of the [Cd2L]2+ fragment. X-ray crystallography Further
- an applied magnetic field of 0.5 and 1.0 Tesla. The observed susceptibility data were corrected for underlying diamagnetism. The synthesis of the complexes are shown in Supporting Information File 1. X-ray crystallography. Single crystals of 3', 5–8 suitable for X-ray crystallography were selected
Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors
Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73
- by NMR, ESIMS, and X-ray crystallography. The utility of this chemistry is further demonstrated by the tests of the novel catalysts (up to 10−2 mol %) in different metathesis reactions such as cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening cross metathesis (ROCM). Keywords: CM
- reagents. The structure of the catalysts were elucidated in detail by 2D NMR and X-ray crystallography. The high catalytic activity of the metallo complexes was demonstrated by several examples of cross metathesis (CM), ring-closing (RCM) and ring-opening cross metathesis (ROCM) reactions. Furthermore
Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts
Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60
- chemical shifts were referenced to TMS. GIAO magnetic shielding tensors were 31.88 for 1H, 182.5 for 13C, values related to the GIAO isotropic magnetic susceptibility. X-ray crystallography. Colorless crystals were isolated for 9{4,7,1} from acetonitrile and used for the following X-ray diffraction studies
A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12
Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42
- . However, after the structural revision of the most active stereoisomer, Kobayashi et al. synthesized (1R,3S)-HPA-12 (2, Figure 1) using a Zn-catalyzed asymmetric Mannich-type reaction in water, and unambiguously ascertained the revised configuration by X-ray crystallography [14]. The other syntheses of
Synthesis, biophysical properties, and RNase H activity of 6’-difluoro[4.3.0]bicyclo-DNA
Beilstein J. Org. Chem. 2019, 15, 79–88, doi:10.3762/bjoc.15.9
- oligonucleotides hybridized to RNA showed a similar structure than the natural DNA/RNA duplex. Furthermore, since the structural investigation on the nucleoside level by X-ray crystallography and ab initio calculations pointed to a furanose conformation in the southern region, a RNase H cleavage assay was
Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands
Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292
- et al. (118, Figure 22) [42]. NMR studies showed that complex 118 exists as a mixture of two rotational isomers in a 7:1 ratio. The major isomer was characterized by X-ray crystallography, while the minor isomer was characterized only in solution and was identified as consistent with two possible
Protein–protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics
Beilstein J. Org. Chem. 2018, 14, 2881–2896, doi:10.3762/bjoc.14.267
- ECSC 10 (Figure 3), which displayed an IC50 in the low micromolar range (IC50 = 40 μM). X-ray crystallography studies revealed that this biphenyl oxime derivative 10 also occupies subsite I of the β-clamp [61]. In 2014, the Zenobia’s First Pass Screen fragment library containing more than 350 fragments
- was screened by X-ray crystallography leading to the identification of four fragment hits. In an attempt to improve their binding affinities, another library was searched for compounds displaying similarity to these initial hits. After a docking-based screening followed by a fluorescence polarization
- fluorimetry) in combination with structural elucidation by combination of NMR and X-ray crystallography have played a pivotal role in identifying and deciphering the crucial target–inhibitor interactions with the aim of treating disease. Although this review covers the description of PPI in bacteria, there
Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine
Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214
- spectroscopy and X-ray crystallography (Figure 1) [38]. Surprisingly, the least thermodynamically stable atropisomer syn-syn-3 was isolated as a main product and the proportion of isomers 1:2:3 was ca. 8:42:50. This observation stimulated us to further investigate the mechanism of the palladium cross-coupling
Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study
Beilstein J. Org. Chem. 2018, 14, 2125–2145, doi:10.3762/bjoc.14.187
- (C6H3-t-Bu2-3,5)2BiCl (5) Colorless single crystals suitable for X-ray crystallography were isolated upon crystallization from a CH2Cl2 solution at ambient temperature (for 4) and at −28 °C (for 5). Compounds 4 and 5·2CH2Cl2 crystallize in the hexagonal space group P63 and orthorhombic space group Pna21
D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation
Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182
- the α-anomers (11), which were separated by column chromatography. No crystals suitable for X-ray crystallography could be obtained from the direct products of the Ritter reaction. To get a more polar molecule which is more appropriate to form crystals suitable for X-ray crystallography, a deprotected
- reaction mixture [35]. The deprotected oxazoline 10j was isolated in nearly quantitative yield. By covering a saturated solution of 10j in 2-propanol with n-heptane crystals suitable for X-ray crystallography were thus obtained. The compound crystallizes in the orthorhombic space group P212121. The
Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates
Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173
- gave molecular ion peaks with expulsion of two (in the case of 4) or four (in the case of 8) N2 fragments due to the lability of the azide group upon laser desorption [39]. The spatial structure of the product 8a was established by X-ray crystallography and is presented in Figure 1 including the atomic
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- X-ray crystallography, studies in solution add valuable information in molecular recognition studies as they take molecular dynamics as well as solvent effects into consideration. In the latter respect, photoaffinity labeling has evolved as a useful tool for studies under physiological conditions [1
A hemicryptophane with a triple-stranded helical structure
Beilstein J. Org. Chem. 2018, 14, 1885–1889, doi:10.3762/bjoc.14.162
- hemicryptophane 1 bearing both amide and amine functions in its three likers. In solution, the 1H NMR spectrum shows a C3 symmetrical cage, which is also observed in the solid state by X-ray crystallography. Moreover, in the solid, amide and amine functional groups of different linkers interact through hydrogen
Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium
Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160
- the formation of the corresponding pincer complexes 17c and 17d directly without formation of an isolable bidentate intermediate observed during the synthesis of complexes 17a and 17b. Furthermore, the successful synthesis of the pincer complexes was confirmed by X-ray crystallography and the
Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant
Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159
- formation of a precipitate consisting of needle-shaped organic crystals and microcrystalline powder of inorganic salts was observed. The needle-shaped organic crystals were manually separated from the inorganic salts and analysed by NMR spectroscopy and X-ray crystallography. 1H and 13C NMR spectra of these
- ) was established by single-crystal X-ray crystallography (for crystallographic details, see Table S1 in Supporting Information File 1). The X-ray structure of an independent unit of IBS-K is shown in Figure 1, and the corresponding structural drawing with interatomic bond distances is presented in
First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones
Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156
- X-ray crystallography (Figure 1). Remarkably, the presence of OH and Cl substituents in products 4i–l results in a bathochromic shift of UV–vis absorptions. The crystal structure of 4k is that of the regioisomer proposed on the basis of reactivity considerations. Since the space group is
Synthesis of spirocyclic scaffolds using hypervalent iodine reagents
Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152
- single crystal X-ray crystallography. Dong and co-workers [90] developed a novel way for the synthesis of five membered spiro pyrazolin-5-ones using amide and amine-containing precursors. Herein, five-membered azaheterocyclic derivatives were synthesized efficiently in presence of PIFA and with TFA as an
- groups. The structure of 75 was confirmed by single crystal X-ray crystallography. 3.2. Using hypervalent iodine reagents as catalysts In 2007, Kita and co-workers [98] investigated the first iodoarene-catalyzed spirocyclization of functionalized amides 76 to spirocyclic systems 77 by carbon–nitrogen
Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies
Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146
- Discussion Solid-state X-ray crystallography Nine X-ray crystal structures were obtained from BrC6 in combination with twelve PyNO guest molecules. Several attempts to obtain single crystals of BrC6 by itself, 1+BrC6, 2+BrC6 and 9+BrC6 in methanol were unsuccessful. In the following discussions, for example
- calculated energies of these bonds, E(x) (kcal/mol), proposed by Espinosa et al. [53][54]. Summary of endo/exo host–guest complexations studied in solution by 1H NMR in comparison to the solid state by single crystal X-ray crystallography. Supporting Information Supporting Information File 222: Experimental
- details, 1H NMR solution-data, X-ray crystallography experimental details and computational data. Acknowledgements The authors gratefully acknowledge financial support from the Academy of Finland (RP grant no. 298817), the University of Jyväskylä, Department of Chemistry, Oakland University, Michigan
A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene
Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134
- recognition of ZB4 using NMR, ITC titration and X-ray crystallography. Similar to TA4, ZB4 is able to host a wide range of organic cations. However, in contrast to TA4, ZB4 shows no large amplitude of conformational response to the electronic nature of substituents on the guests, and its binding affinities
One hundred years of benzotropone chemistry
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
An overview of recent advances in duplex DNA recognition by small molecules
Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93
- surface plasmon resonance, X-ray crystallography and molecular modeling [130]. These experiments revealed that these novel conjugates form 1:1 complexes
Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle
Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87
- oxidation of 2-iodo-N,N’-diisopropylisophthalamide with m-chloroperoxybenzoic acid under mild conditions. Single crystal X-ray crystallography of this compound revealed a five-membered bis-heterocyclic structure with two covalent bonds between the iodine atom and the nitrogen atoms. This novel benziodazole
- and peptides [23][24][25]. Numerous examples of five-membered hypervalent iodine(III) heterocycles containing other than oxygen heteroatoms, such as sulfur [26], boron [27][28], phosphorous [29], or nitrogen [30][31][32], have been synthesized and characterized by X-ray crystallography. In particular
- refrigerator for several weeks. Solutions of 7a in CDCl3 or CD3CN did not show any decomposition even after storage for over one month at room temperature. The solid state structure of compound 7a was characterized by X-ray crystallography. A single crystal X-ray diffraction of 7a confirmed the bicyclic
Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies
Beilstein J. Org. Chem. 2018, 14, 838–848, doi:10.3762/bjoc.14.69
- characterization of the cholesterol/β-CD inclusion complex [22], its binding affinity [23][24][25], the inclusion mode of the complex [26] and its dynamic behavior through MD simulations [27][28][29] but its crystal structure is absent. In this work, the structure of CHL/β-CD is determined by X-ray crystallography
- dimers [24][25][33]. In this study, the determination by X-ray crystallography of the CHL inclusion in a head–head β-CD dimer conclusively resolves this ambiguity. The binding affinity calculations based on this model give high absolute ΔG values at both 300 K and 340 K temperatures (Table 2) indicating
- the slow cooling crystallization technique. More specific, 10.22 mg (0.026 mmoles) of CHL were added in a 2 mL equimolar aqueous solution of β-CD. The mixture was stirred at 70 °C for 4 h and gradually cooled to room temperature over a period of seven days. X-ray crystallography A prismatic colorless
Phosphodiester models for cleavage of nucleic acids
Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68
- of nucleases by pH-rate dependency, X-ray crystallography, amino acid/nucleotide substitution and computational approaches, experimental and theoretical studies with small molecular model compounds still play a role. With small molecules, the importance of various elementary processes, such as proton
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