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Search for "HPLC" in Full Text gives 800 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

  • Wilfred J. M. Lewis,
  • David M. Shaw and
  • Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

Graphical Abstract
  • configurationally unstable in aqueous solution. Chiral HPLC analysis of samples of pyrrolizixenamide A isolated from culture clearly indicated racemic specimens but also revealed the presence of the two C(7a)-hydroxylated derivatives whose presence in the mixture became enriched during purification. Taken together
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Published 02 Feb 2021

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

  • Olga Gherbovet,
  • Fernando Ferreira,
  • Apolline Clément,
  • Mélanie Ragon,
  • Julien Durand,
  • Sophie Bozonnet,
  • Michael J. O'Donohue and
  • Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

Graphical Abstract
  • lignocellulosic matrix. Moreover, Faes are useful tools to obtain commercially relevant ferulic acid, which represents up to 3 wt % of plant the cell wall dry weight [8]. So far, the detection and characterization of Faes has mainly relied on either the use of HPLC or on UV–visible spectrophotometry, using
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Published 01 Feb 2021

19F NMR as a tool in chemical biology

  • Diana Gimenez,
  • Aoife Phelan,
  • Cormac D. Murphy and
  • Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

Graphical Abstract
  • convenient technique to study a range of factors that might influence the plasma and metabolic stability of the lead compounds, proving itself as a valuable alternative to more challenging conventional HPLC or 1H NMR analyses. It is also worth noting that recent investigations within the Dalvit group have
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Published 28 Jan 2021

1,2,3-Triazoles as leaving groups in SNAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

  • Kārlis-Ēriks Kriķis,
  • Irina Novosjolova,
  • Anatoly Mishnev and
  • Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

Graphical Abstract
  • conversion of starting material 6d was monitored by HPLC, and after completion, product 4d was precipitated from the reaction mixture by hexane. For entries 1 and 3 in Table 2, an extra purification step by silica gel column chromatography was required. For compound 4d, the optimal reaction conditions were 2
  • compounds were monitored by HPLC and TLC analysis using silica gel 60 F254 aluminum plates (Merck). Visualization was accomplished by UV light. Column chromatography was performed on silica gel (60 Å, 40−63 μm, ROCC). The yield of the products refers to chromatographically and spectroscopically homogeneous
  • 1H,13C-HSQC 2D NMR experiments for representative products of each compound class. Crystallographic diffraction data were collected with a NoniusKappa CCD diffractometer (Mo Kα, λ = 0.71073 Å) equipped with a low-temperature Oxford Cryosystems Cryostream Plus device. HPLC analysis was performed using
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Published 20 Jan 2021

Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders

  • David Straßburger,
  • Svenja Herziger,
  • Katharina Huth,
  • Moritz Urschbach,
  • Rainer Haag and
  • Pol Besenius

Beilstein J. Org. Chem. 2021, 17, 97–104, doi:10.3762/bjoc.17.10

Graphical Abstract
  • purified by RP-HPLC and separated from impurities, like disubstituted byproduct, to finally afford 5 in 68% yield. Subsequently, an azide functionality was easily introduced using azidoacetic acid NHS ester to obtain compound 6. In the next step, the solubilizing side-arm 4 was attached twice to the
  • copper-catalyzed azide–alkyne cycloaddition (Scheme 2). The reaction took place in degassed DMSO at 50 °C with CuSO4 pentahydrate, sodium ascorbate and tris(benzyltriazolylmethyl)amine (TBTA) as chelating species. HPLC-monitoring of the reaction showed a full conversion after three days and the crude
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Published 12 Jan 2021

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

  • Dimas J. P. Lima,
  • Antonio E. G. Santana,
  • Michael A. Birkett and
  • Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

Graphical Abstract
  • precursor (−)-75 was 97.6%, determined by HPLC. The overall yield for this synthesis was 13.4% and specific rotation [α]D25 −13.0 (c 0.73, CHCl3) {lit. [α]D −13 (CHCl3), [17]}. Spino synthesis – 2009 Spino et al. synthesized both (−)-adaline (1) and (+)-euphococcinine (2) [53]. The main features in this
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Published 05 Jan 2021

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

  • Daria I. Tonkoglazova,
  • Anna V. Gulevskaya,
  • Konstantin A. Chistyakov and
  • Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

Graphical Abstract
  • band gaps (by ≈0.5 eV). In cases of pyrazine and pyridine-fused analogs, differences are not so noticeable. Experimental The synthetic procedures, HPLC, X-ray studies and spectra (1H and 13C NMR) of all new compounds can be found in Supporting Information File 1. Molecular structure of carbazole-based
  • ]helicenes 10. Supporting Information Supporting Information File 76: Experimental procedures and analytical data, copies of 1H and 13C NMR spectra of all new compounds, X-ray data for 9c and 10a–c, HPLC spectra of helicenes 10a–c, UV–vis and fluorescence spectra of 10a–c. Acknowledgements The authors
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Published 04 Jan 2021

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

  • Joon Min Cha,
  • Dong Hyun Kim,
  • Lalita Subedi,
  • Zahra Khan,
  • Sang Un Choi,
  • Sun Yeou Kim and
  • Chung Sub Kim

Beilstein J. Org. Chem. 2020, 16, 3078–3085, doi:10.3762/bjoc.16.257

Graphical Abstract
  • data were acquired on a Waters SYNAPT G2 (Milford, MA, USA). The HPLC–DAD–MS data were measured using an Agilent 1260 Infinity HPLC system (Agilent, Santa Clara, CA, USA) with a Kinetex C18 5 μm column (250 mm length × 4.6 mm i.d.; Phenomenex, Torrance, CA, USA). Purification was achieved using a semi
  • -preparative HPLC system equipped with a Gilson 306 pump (Middleton, WI, USA), a Shodex refractive index detector (New York, NY, USA), a Luna C18 10 µm column (250 mm length × 10 mm i.d.; Phenomenex, Torrance, CA, USA), and an Apollo Silica 5 μm column (250 mm length × 10 mm i.d.; Apollo, Manchester, UK) at a
  • g) was chromatographed on an RP-C18 silica gel column (90% aqueous MeOH) to yield 12 subfractions (H3-1–H3-12), and compound 11 (5 mg) was obtained from subfraction H3-12 (50 mg) by semi-preparative normal-phase HPLC (hexanes/EtOAc 8:1). The CHCl3-soluble fraction (15 g) was subjected to passage
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Published 17 Dec 2020

Controlled decomposition of SF6 by electrochemical reduction

  • Sébastien Bouvet,
  • Bruce Pégot,
  • Stéphane Sengmany,
  • Erwan Le Gall,
  • Eric Léonel,
  • Anne-Marie Goncalves and
  • Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

Graphical Abstract
  • controlled decomposition of sulfur hexafluoride was described under electroreduction. The reduction potential was firstly determined and used for preparative studies. The extrapolation on large scale of this methodology is under current development in our laboratory. Experimental Acetonitrile (HPLC grade
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Published 01 Dec 2020

Incorporation of a metal-mediated base pair into an ATP aptamer – using silver(I) ions to modulate aptamer function

  • Marius H. Heddinga and
  • Jens Müller

Beilstein J. Org. Chem. 2020, 16, 2870–2879, doi:10.3762/bjoc.16.236

Graphical Abstract
  • hydrogen citrate (Supporting Information File 1, Table S1, Figures S9–S20). The purity was confirmed by means of HPLC chromatography (Figures S21–S32, Supporting Information File 1). Towards this end, a Macherey–Nagel NUCLEODUR C18 HTec column (5 μm, 124 × 4 mm) was used in combination with the following
  • ATP, oligonucleotide sequences, MALDI–TOF spectra of the oligonucleotides and HPLC traces to confirm the oligonucleotide purity. Acknowledgements We thank D. Defayay for performing the HPLC analysis of the oligonucleotides.
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Published 25 Nov 2020

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

  • David Liese,
  • Hans Henning Wenk,
  • Xin Lu,
  • Jochen Kleinen and
  • Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

Graphical Abstract
  • C12, with a little portion of double bonds (according to HPLC–MS measurements this portion amounts to ca. 4–12%). A novel synthetic route was chosen for the synthesis of the dirhamnolipid esters. In contrast to the previously used methods [26][27][28], our approach is applicable for any desired alkyl
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Published 19 Nov 2020

Synthesis and investigation of quadruplex-DNA-binding, 9-O-substituted berberine derivatives

  • Jonas Becher,
  • Daria V. Berdnikova,
  • Heiko Ihmels and
  • Christopher Stremmel

Beilstein J. Org. Chem. 2020, 16, 2795–2806, doi:10.3762/bjoc.16.230

Graphical Abstract
  • , and FkrasT. 9-(Azidoalkyl)berberine derivatives 3a–e [54] and 9-propargyladenine (2) [53] were synthesized according to published procedures. Stock solutions of the ligands (1.0 mM) were prepared in MeOH (HPLC grade). Buffer solutions were prepared with biochemical grade chemicals in E-Pure water
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Published 18 Nov 2020

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of 1JC,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

  • Md. Rokon Ul Karim,
  • Enjuro Harunari,
  • Amit Raj Sharma,
  • Naoya Oku,
  • Kazuaki Akasaka,
  • Daisuke Urabe,
  • Mada Triandala Sibero and
  • Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

Graphical Abstract
  • those of synthetically prepared model imidazoles. The absolute configurations of the anteisoalkanoyl group present in 1, 4, and 5 were determined by low-temperature HPLC analysis of the degradation products labeled with a chiral anthracene reagent, which revealed that 1 is a mixture of the R- and S
  • anthracene reagent to yield the esters of (R)- or (S)-2-(anthracene-2,3-dicarboximido)propanol (nat-10-(R)-2A1P, (S)-10-(R)-2A1P, and (S)-10-(S)-2A1P), which were subjected to HPLC analysis for comparison (Figure 4). The retention times of the standard samples were 177 min for (S)-10-(S)-2A1P
  • of nocarimidazole B (4) produced by strain TK35-5. The same compound was originally isolated from marine Nocadiopsis, but the absolute configuration was not elucidated. The conversion of 4 into the derivative nat-11-(R)-2A1P, followed by HPLC analysis, revealed that 4 is an enantiomerically pure S
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Published 05 Nov 2020

Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides

  • Dongsik Yang,
  • Hongjian He and
  • Bing Xu

Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221

Graphical Abstract
  • , we used TFA at room temperature for 2 h to cleave the tert-butyl protecting groups of 1b and 2b. After adding diethyl ether to precipitate the crude peptides, centrifugation, and washing three times, we used reversed-phase HPLC and acetonitrile (containing 0.1% TFA) and double-distilled water
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Published 04 Nov 2020

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

  • Lena Reinke,
  • Julia Bartl,
  • Marcus Koch and
  • Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

Graphical Abstract
  • acid by using O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU) as the coupling reagent. The yield in this step only amounted to 51% because the product had to be purified by preparative HPLC to obtain it in analytically pure form. The enantiomerically pure analog (R)-1 was
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Published 02 Nov 2020

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

  • Yuvixza Lizarme-Salas,
  • Alexandra Daryl Ariawan,
  • Ranjala Ratnayake,
  • Hendrik Luesch,
  • Angela Finch and
  • Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

Graphical Abstract
  • difluorinated acid 20. Finally, coupling of the acid 20 with piperidine afforded the target compound 2 in moderate yield (Scheme 3). The enantiopurity of 2 was investigated using chiral HPLC. From a spectroscopically pure sample of 2, two HPLC peaks were observed, with an integral ratio of 99:1. It is assumed
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Published 28 Oct 2020

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases

  • Julia N. Artsemyeva,
  • Ekaterina A. Remeeva,
  • Tatiana N. Buravskaya,
  • Irina D. Konstantinova,
  • Roman S. Esipov,
  • Anatoly I. Miroshnikov,
  • Natalia M. Litvinko and
  • Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2020, 16, 2607–2622, doi:10.3762/bjoc.16.212

Graphical Abstract
  • The resulting PF-1Pis have been studied in three ways: (1) after completion of the phosphorolysis, Dowex-nPi was filtered off, the recombinant E. coli PNP and a purine base were added to the filtrate, and the formation of the desired purine nucleoside was monitored by TLC and HPLC, (2) the resulting
  • , OMG and E. coli PNP were added to the combined filtrate and washings, and the resulting new reaction mixture was stirred at 55 °C for 120 h (Scheme 3B); the progress of the reaction was monitored by TLC and HPLC. The ca. 1:2 (mol) ratio of the purine base to the crude Ara-1Pi was chosen from the
  • -nPi (6 mL; 1.2 mequiv/mL) and MgCl2·6H2O (0.35 mmol) catalyzed by UP (105 IU; 150 units per 1 mmol of substrate) at 40 °C for 72 h giving rise to the formation of uracil in practically quantitative yield (>97%) according to HPLC analysis. The reaction mixture was worked up as described above, the
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Published 22 Oct 2020

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

  • Emine Kayahan,
  • Mathias Jacobs,
  • Leen Braeken,
  • Leen C.J. Thomassen,
  • Simon Kuhn,
  • Tom van Gerven and
  • M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

Graphical Abstract
  • mixers [44]. The photocatalytic oxidation of methionine was performed in the Corning laboratory reactor. Two LED panels coupled with heat exchangers were placed on both sides of the reactor. Flow was supplied with an HPLC pump. Full conversion was achieved with a residence time ranging from 0.6 min to
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Published 08 Oct 2020

Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis

  • David Van Craen,
  • Jenny Begall,
  • Johannes Großkurth,
  • Leonard Himmel,
  • Oliver Linnenberg,
  • Elisabeth Isaak and
  • Markus Albrecht

Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195

Graphical Abstract
  • -Alder reaction at hierarchical helicates with solvent and chiral ligand screening. Enamine-catalyzed nitro-Michael reaction with hierarchically assembled helicates.a Supporting Information Supporting Information File 446: Synthetic procedures, characterization data, SFC and HPLC conditions and copies
  • of 1H and 13C NMR spectra of new compounds. Acknowledgements We sincerely thank Prof. Magnus Rüping, Cornelia Vermeeren, Prof. Carsten Bolm and Marcus Frings for the determination of the enantio- and diastereoselectivities via SFC and HPLC. Parts of this publication have been published in the Ph.D
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Published 24 Sep 2020

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

  • Patrizia Andreozzi,
  • Lorenza Tamberi,
  • Elisamaria Tasca,
  • Gina Elena Giacomazzo,
  • Marta Martinez,
  • Mirko Severi,
  • Marco Marradi,
  • Stefano Cicchi,
  • Sergio Moya,
  • Giacomo Biagiotti and
  • Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

Graphical Abstract
  • JEM 1010 microscope, operating at an acceleration voltage of 120 kV. A fresh solution of Dex-1b was prepared at a concentration of 10 mg/mL in ultra-HPLC water, and sonicated for 15 s at room temperature. A short spin of 30 seconds at 10 krpm was applied in order to remove the big aggregates and dust
  • . The stock solution was diluted 1:2 in ultra-HPLC water, and 1 μL of the solution was deposited on the top of the TEM grid and left dried at room temperature. Steady state fluorescence measurements were performed on a Fluorolog®-3 spectrofluorometer (Horiba-Jobin Yvon) using 1.0 × 1.0 cm quartz cuvette
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Published 11 Sep 2020

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

  • Benjamin Jeffries,
  • Zhong Wang,
  • Robert I. Troup,
  • Anaïs Goupille,
  • Jean-Yves Le Questel,
  • Charlene Fallan,
  • James S. Scott,
  • Elisabetta Chiarparin,
  • Jérôme Graton and
  • Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

Graphical Abstract
  • by reversed-phase HPLC). Lipophilicity modulations discussed in this contribution. Distribution of the experimental lipophilicity values of series D, E and F (* denotes an estimated value, see Supporting Information File 1). Comparison of lipophilicities between the linear alkyl, isopropyl
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Published 02 Sep 2020

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

  • Alexander N. Reznikov,
  • Dmitry S. Nikerov,
  • Anastasiya E. Sibiryakova,
  • Victor B. Rybakov,
  • Evgeniy V. Golovin and
  • Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

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  • of Henry/acetalyzation reaction with phosphonate 6ea. Supporting Information Supporting Information File 451: Experimental procedures, copies of NMR, FTIR, and mass spectra, HPLC and X-ray diffraction data. Supporting Information File 452: Crystallographic information files (CIF). Funding The
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Published 25 Aug 2020

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

  • Annike Weißenstein,
  • Myroslav O. Vysotsky,
  • Ivo Piantanida and
  • Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

Graphical Abstract
  • second step, the naphthalene nucleus was functionalized via a nucleophilic aromatic substitution with the Boc-protected amino acids ʟ-Dap and ʟ-Lys. The reaction was carried out in dry DMSO at 60–65 °C for 1.5–2 hours. After two preparative HPLC purifications in an acidic environment (with TFA) and
  • preparative HPLC and treatment with 1 M HCl solution, NDI 5 with three cationic substituents at the imide and bay positions could be obtained in 44% yield. The 1H, 13C NMR data, and high-resolution mass spectra correspond well with the structures of all new compounds synthesised. Spectrophotometric properties
  • ), calf thymus (ct)-DNA, and poly(dG-dC)2 were obtained from Sigma–Aldrich. The starting compound 1 was prepared according to the literature [31]. Column chromatography was performed on silica gel (MerckSilica 60, particle size 0.04–0.063 mm). Semipreparative HPLC was performed on a Jai system (LC-9105
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Published 19 Aug 2020

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

  • Goutam Ghosh and
  • Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

Graphical Abstract
  • peptide from the solid support, and iv) purification of the peptide by reversed-phase HPLC. Fmoc-protected Rink amide resin (0.45 g, 0.5 mmol) was swelled in 10 mL of DMF for two hours. After that, the swelled resin was loaded into the special apparatus [23], and the solvent was drained off. The swelled
  • . The lyophilized peptide was dissolved in water/acetonitrile 1:1, v/v, in the presence of 0.1% TFA and purified by RP-HPLC using eluent A (10% acetonitrile, 90% water containing 0.1% TFA) and eluent B (80% acetonitrile, 20% water containing 0.1% TFA) in a linear acetonitrile→water gradient (11% B→50% B
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Published 17 Aug 2020

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

  • Jundi Xue,
  • Ziyi Han,
  • Gen Li,
  • Khalisha A. Emmanuel,
  • Cynthia L. McManus,
  • Qiang Sui,
  • Dongmian Ge,
  • Qi Gao and
  • Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

Graphical Abstract
  • )-3-hydroxytetradecanoate (5) in 98% yield. The same hydrogenation reaction was carried out using the (S)-Ru(OAc)2(BINAP) catalyst. Then both the R and S products were compared using chiral HPLC to confirm the absolute configuration and enantiomeric purity (Figure S1, Supporting Information File 1
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Published 10 Aug 2020
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