Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• events in which all bonds involved in the cycloaddition are formed and broken and (ii) a second one consisting of the deprotonation of the nitrogen yielding a neutral compound and liberating the catalyst. The comparative quantitative analysis of the noncovalent interactions (NCI) [35][36] of fused

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

• excellent alternative parameters for the quantitative analysis of site-specific intramolecular distances, with a more particular significant value in the exploration of large proteins and macromolecular complexes where substrate spectral crowding and/or background incompatibility prevents the use of other

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• . Figure 4 shows the data at a scattering angle of θ = 90° for cycle I and II to indicate these size distributions of the assemblies formed in solution. For a quantitative analysis and the hydrodynamic radii quoted, angular extrapolated values are used. For each sample of both cycles, one main peak is

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• clear for the synthesis of β-CDMts, the magnitude of their contribution can nevertheless be assigned in a consistent way through the quantitative analysis depicted in this study. In view of the results, grinding and amorphization of the CDs are not systematically favorable to reactivity. Moreover

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• sedimentary rocks present in this area. Catalyst characterization The NDL catalyst was ground into a fine powder and then sieved in a 200-mesh sieve. The chemical composition of the catalyst was determined by standard quantitative analysis. The basic strength of the catalyst was analyzed by using Hammett

• indicators. The catalyst was characterized by XRD, IR, Raman, SEM, and EDAX analysis. The chemical composition of the NDL was determined by adopting a standard quantitative analysis [75]. The obtained results are summarized in Table 1. The basic strength of the NDL catalyst (H_) was measured using Hammett

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• , β-carbolines are also used as fluorescence standards. Recently, a novel β-carboline-based fluorescent chemosensor was developed by Batra and co-workers for the quantitative analysis of fluoride ions (F−) at ppb level [19]. Sulfur-containing organic compounds are broadly associated with numerous

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• measurements, without any significant loss of the unpolarized emission intensity. This behavior, which precluded a quantitative analysis of the CPL properties, may be attributed to a photoinduced racemization process. The differences in configurational stability of boomerangs are reproduced by DFT calculations

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• properties. Traditionally, organic dyes are the basis of well-established color indicators for qualitative and quantitative analysis. Nowadays, we cannot imagine research in the life sciences or in medical diagnostics without the sophisticated applications of organic dyes as fluorescent probes, dye labels

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• diffusion coefficient of 7.06 × 10−11 m2/s attributable to the 7+6 pseudo[2]rotaxane as TFPB− salt and significantly lower than that measured for the free triple-calix[6]arene host 6 of 3.02 × 10–10 m2/s. Through an 1H NMR quantitative analysis of a 1:1 mixture of 7+·TFPB– and 6 in CDCl3, using 1,1,2,2

New standards for collecting and fitting steady state kinetic data

• Kenneth A. Johnson

Beilstein J. Org. Chem. 2019, 15, 16–29, doi:10.3762/bjoc.15.2

• quantitative analysis, fulfilling the major goal of their work [1][2]. Estimating the binding affinity for the substrate as KS was an added bonus. These were profound discoveries that laid the foundation for enzymology throughout the 20th century. The Michaelis–Menten equation was originally derived assuming

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• remark, it is well known that the CP-MAS technique allows also a semi-quantitative analysis of the signals in the spectrum [11]. It is interesting to notice that along the series CaNS1–CaNS3 the area of the aliphatic signal at ca. 32 ppm increases as compared to cumulative area of the aromatic signals

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• or even higher than the IC50 value of the other compounds 2, 4 and 5. It can be assumed that this effect occurred due to the reduced release of the smallest Dau-containing metabolite. Confocal laser scanning microscopy (CLSM) studies Next to the quantitative analysis of the cellular uptake by flow

• co-localization with nuclei, DAPI-staining was performed. Images are displayed in BestFit mode to improve visualization of low signals and to optimize the image quality. The CLSM observations cannot be considered as quantitative analysis but provide qualitative information about subcellular

Enzyme-free genetic copying of DNA and RNA sequences

• Marilyne Sosson and
• Clemens Richert

Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47

• assays with immobilized primer–template duplex (Figure 10). The insights gained from the quantitative analysis of primer extension leaves several options to push assays to completion. The first is to employ highly reactive and well binding monomers only. For RNA, this approach does not appear realistic

Structural diversity in the host–guest complexes of the antifolate pemetrexed with native cyclodextrins: gas phase, solution and solid state studies

• Magdalena Ceborska,
• Magdalena Zimnicka,
• Aneta Aniela Kowalska,
• Kajetan Dąbrowa and
• Barbara Repeć

Beilstein J. Org. Chem. 2017, 13, 2252–2263, doi:10.3762/bjoc.13.222

• interaction strength in solution. The increased influence of hydrophobic effects on the overall stabilities of CDs/FA complexes was observed in experiments in which a mass spectrometer was treated as a detector for quantitative analysis of CDs/FA complexes. Only these experiments enabled the solution-like

(Z)-Selective Takai olefination of salicylaldehydes

• Stephen M. Geddis,
• Caroline E. Hagerman,
• Warren R. J. D. Galloway,
• Hannah F. Sore,
• Jonathan M. Goodman and
• David R. Spring

Beilstein J. Org. Chem. 2017, 13, 323–328, doi:10.3762/bjoc.13.35

• was observed (Figure 1). Whilst Hammett parameters are not tabulated for ortho-substitution, precluding an analogous quantitative analysis, the trend for ortho-halogenated substrates is qualitatively similar, although with even higher amounts of (Z)-product. This implies that electron-withdrawing

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• when nuclei are submitted to a strong magnetic field [13]. NMR spectroscopy is one of the most powerful and versatile methods for structural determination, enabling qualitative and quantitative analysis of samples. It can be applied to almost all elements in the periodic table, the only requirement

• reproducibility and the accuracy of the quantitative analysis of the reaction, especially if mixing is not perfect, the analyzed sample may be not representative of the whole reaction. Finally, this is an interdisciplinary field with implications in chemistry, physics, engineering and mathematics and with many

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• the quantitative analysis. The addition of CB[7] also affected the emission properties of ligand 2 (Supporting Information File 1, Figure S3). Specifically, the two emission maxima at 434 nm and 571 nm decreased, both at pH 7 and 5, without a shift of the emission maxima. As a general trend, the long

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• the solid state. The CP dynamic regime can be explored by acquiring several experiments at increasing contact time (CT). This methodology is called Variable Contact Time (VCT); generally, the CT is increased from few μs to some ms. A quantitative analysis of the CP data can be performed by fitting the

• resonances and quantitative analysis of SS 1H NMR spectra is still very challenging. The spectral resolution can be improved by applying line narrowing techniques such as magic angle sample spinning (MAS) [20], usually combined with complex homonuclear decoupling pulse sequences designed ad hoc [21][22]. The

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• structure–selectivity relationship was carried out by Davies and Sigman [27]. The quantitative analysis of the substrate and the reagent shows that a non-bulky electron-rich carbene and a non-bulky catalyst prefer secondary or tertiary C–H bonds, while bulky electron-deficient carbene and bulky catalysts

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• recent study, Tang and coworkers [52] performed a quantitative analysis of counterion exchange in cobaltocene-containing polyelectrolytes that are accessible by an initial ROMP, and subsequently derivatized with cobalt motifs. These results appear to be relevant for self-assembly and drug-delivery

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• the transmission function of the electron analyzer and the pertinent photoionization cross sections [43]. In the calculations, a homogeneous composition of the analyzed layer of the measured samples was assumed. The typical error for the quantitative analysis by XPS was approximately 10% [44]. The

Qualitative evaluation of regioselectivity in the formation of di- and tri-6-O-tritylates of α-cyclodextrin

• Keisuke Yoshikiyo,
• Yoshihisa Matsui and
• Tatsuyuki Yamamoto

Beilstein J. Org. Chem. 2015, 11, 1530–1540, doi:10.3762/bjoc.11.168

• Keisuke Yoshikiyo Yoshihisa Matsui Tatsuyuki Yamamoto Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan 10.3762/bjoc.11.168 Abstract The quantitative analysis of reaction products showed that the reaction of 6A,6D-di-O-trityl-α

• ,6C-di-O-trityl-α-CD’s. Keywords: 1H and 13C NMR spectroscopy; quantitative analysis; regioselectivity; tritylation; ultra-fast liquid chromatography (UFLC); Introduction Regioselective modification and deprotection on the primary hydroxy side of cyclodextrins (CDs) are of great importance in

• , respectively), the ABE-isomer will be the minor product and the ABD-isomer the major one. The quantitative analysis of the product in this reaction revealed that the ABE-isomer is formed in a smaller amount than the ABD-isomer, with a mole ratio of 0.25 ± 0.02:1.00 (Figure 7). This result indicates that the

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• important in biochemistry [1] and supramolecular chemistry [2], but still not fully understood on the level of individual non-covalent interactions [3]. Synthetic supramolecular systems are ideal for a quantitative analysis of multivalency on the level of single molecules, because specific ligand design can

Anion effect controlling the selectivity in the zinc-catalysed copolymerisation of CO₂ and cyclohexene oxide

• Sait Elmas,
• Muhammad Afzal Subhani,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 42–49, doi:10.3762/bjoc.11.7

• characteristic for the C–O–C bending vibration assigned to the ether linkages, while the intensity of the signal at 805 cm−1 characteristic for CHO decreased in parallel (Figure 1). At 1746 cm−1, the typical carbonate band [νst(C=O)] [25] appeared with low intensity. Quantitative analysis of the time-resolved IR

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• quantitative analysis of primary amino groups on nanodiamond has been developed and tested with a broad variety of aminated diamond samples. The modified conditions ensure the formation of sufficient amounts of the required hydrindantin intermediate and deliver reproducible and comparable results. The method