The effect of cyclodextrin complexation on the solubility and photostability of nerolidol as pure compound and as main constituent of cabreuva essential oil

• Joyce Azzi,
• Pierre-Edouard Danjou,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2017, 13, 835–844, doi:10.3762/bjoc.13.84

• (randomly methylated β-CD, RAMEB, or a low 2-O-methylated-β-CD, CRYSMEB) and sulfobutylether-β-CD (SBE-β-CD) (Figure 1). Molecular complexation in CDs has been widely proposed for EOs to limit their degradation during processing and storage and to offer a good dispersion of compounds in the aqueous media

• -Ner isomer leading to a more stable inclusion complex [16]. An exception is observed for γ-CD, where cis-Ner is better encapsulated than trans-Ner, owing to the larger cavity of this CD. Phase-solubility studies also allow the determination of the complexation efficiency (CE) permitting to evaluate

• solubility studies. Indeed, formation constants determined by this method are generally overestimated since several effects are combined and not only complexation [25]. Phase solubility studies of cabreuva essential oil Phase solubility studies were also performed for the cabreuva EO, an EO rich in trans-Ner

Synthesis of ribavirin 2’-Me-C-nucleoside analogues

• Fanny Cosson,
• Aline Faroux,
• Jean-Pierre Baltaze,
• Jonathan Farjon,
• Régis Guillot,
• Jacques Uziel and
• Nadège Lubin-Germain

Beilstein J. Org. Chem. 2017, 13, 755–761, doi:10.3762/bjoc.13.74

• mixture by α- and β-attack; this second one can be explained by a magnesium complexation with the base. More interestingly, the methylation proceeded stereoselectively leading to 13b in 87% yield when trimethylaluminium was used [24]. The stereochemical outcome of this reaction was determined by selective

Inclusion complexes of β-cyclodextrin with tricyclic drugs: an X-ray diffraction, NMR and molecular dynamics study

• Franca Castiglione,
• Fabio Ganazzoli,
• Luciana Malpezzi,
• Andrea Mele,
• Walter Panzeri and
• Giuseppina Raffaini

Beilstein J. Org. Chem. 2017, 13, 714–719, doi:10.3762/bjoc.13.70

• single bond. The lack of disorder in the C9–C10 segment suggests that complexation constrains 2 in a single conformation in the solid state. The MD simulations led to the formation of a 1:1 inclusion complex of β-CD with molecules 1 and 2 both in vacuo and in explicit water. In both cases, the complex

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• negatively-charged polysaccharide, and shown by AFM, DLS and TEM, to have formed nano-aggregates of up to 250 nm. Interestingly, the emissive properties of the CDs were unchanged upon complexation to HA. The resultant nano-aggregates were then loaded with doxorubicin (DOX) and a strong correlation between

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• )anthraquinones with a series of cations demonstrated their high binding affinity to Cu2+, Al3+, and Cr3+. Keywords: amination; aminocholanes; bile acids; cation complexation; Cu-catalysis; diaminoanthraquinone; Pd-catalysis; Introduction Bile acids are known to ensure vital processes in vertebrate organisms

• react with aryl halides to provide a wide range of products in excellent yields. However, yet there was no evidence of the same technique being applied to steroidal amines. Our particular interest was drawn by the synthesis of cholane-diaminoanthraquinone derivatives that can possess good complexation

• in the arylation of cholic acid derived amine 3c with 6a affording 34% of 5e. Thus, Pd-catalyzed amination seems to be a very competitive route for the preparation of arylated aminocholanes. Complexation of bile acid derived ligands Steroidal ligands are known to be excellent hosts for different ions

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• decrease in the intensity of the original absorption bands of receptors R1 and R2 centered at 395 nm and 459 nm, respectively, and the gradual increase of the bands centered at 492 nm and 560 nm with clear isosbestic points indicates the complexation process. It is assumed that the AcO− ions interacted

• the hydroxy group. An isosbestic point is observed at 323 nm representing the interaction of Hg2+ with R1 involving the imine group and the oxygen of the hydroxy group. The corresponding B–H plot displayed a 1:1 complexation ratio between R1 and Hg2+ ion. A picture of the observed color change and the

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

• this ligand increase by about two to three orders of magnitude, respectively, when bound to CB[7]. Keywords: azoniahetarenes; cucurbit[7]uril; heterocycles; photoacids; supramolecular photochemistry; Introduction The complexation of ligands by macrocyclic host molecules, such as crown ethers

• ] hosts with high affinity [6]. In most cases, this complexation strongly affects the chemical or physical properties of the ligand. For example, it was demonstrated that the optical properties of organic dyes may be modified drastically upon complexation in the CB cavity [7]. At the same time, this

• photoreactions that are not possible in homogeneous solution [10][11][12][13][14][15]. Considering the importance of acid–base equilibria in chemistry and biology it is also tempting to employ the reversible complexation of acidic or alkaline guest molecules with CB[n] for the controlled modification of their

Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones

• Vinicius R. Campos,
• Ana T. P. C. Gomes,
• Anna C. Cunha,
• Maria da Graça P. M. S. Neves,
• Vitor F. Ferreira and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2017, 13, 195–202, doi:10.3762/bjoc.13.22

• ]. The use of the porphyrin zinc complex avoids the complexation of the tetrapyrrolic macrocycle with Pd(II) formed during the catalytic cycle, and in this way prevents the loss of the catalyst. In the first experiments, the reactions between 2-bromo-5,10,15,20-tetraphenylporphyrinatozinc(II) (1) and the

Phosphated cyclodextrins as water-soluble chiral NMR solvating agents for cationic compounds

• Cira Mollings Puentes and
• Thomas J. Wenzel

Beilstein J. Org. Chem. 2017, 13, 43–53, doi:10.3762/bjoc.13.6

• higher degree of complexation. However, in some spectra there have been an overlap of one of the substrate resonances with other resonances of the substrate or CD in such a way that it was not possible to determine in a regular one-dimensional NMR spectrum whether enantiomeric differentiation was present

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• when linked to nanoTiO2 colloids leading to restriction of charge–hole recombination [35]. The efficiency is further improved by keeping the ligands close to the surface of nanoTiO2 via inclusion complexation. In other studies the presence of CDs caused a delay in the photocatalytic degradation of

• -stabilized nanoTiO2 as additive hardly any decrease in the drug concentration upon UV irradiation was measured especially in tap water. It is well-known that the complexation often has a protective effect on the included guest molecules [8]. Either catalysis or inhibition of the light-induced cleavage can

• is deeply included into the cavity [51], while MB is too large to be completely shielded by complexation. The too strong association between IBR and the cavities of CMBCD-P can be a possible reason of protection instead of catalytic decomposition in this process. Further experiments are needed to

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• protein’s N-terminus. Spectral analysis of StaF showed that it exhibits the typical P450 absorption spectra, but with only half of the StaF species being in the catalytically competent state upon reduction and CO-complexation. Despite this, we successfully reconstituted the StaF activity in vitro and could

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• chloride complexation, the provided X-ray data are consistent with L13 acting as hydrogen bond donors (Scheme 10B). The published X-ray data for the chloride and bromide salts of L13 with R2 = C6F5 indeed provide evidence of anion–π bonding with the C6F5 group. In addition, we also noted that there is

• bond-donor catalysts by Bibal and co-workers [53][54]. Tetraalkylammonium catalyst (L6)-catalyzed dearomatization of isoquinolinium salts [50]. Tetraalkylammonium catalyst L6 complexation to halogen-containing substrates [51]. Tetraalkylammonium-catalyzed aza-Diels–Alder reaction by Maruoka and co

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• solution, the complexation is enthalpically and entropically driven. In addition, complementary interactions (e.g., van der Waals forces, H-bonds, etc.) appear between the CD and the guest. The non-polar suitably-sized guest may be bound in numerous molar ratios (e.g., 1:1, 2:1, 1:2, etc.). In all cases

• , the knowledge of the binding constants (Kass) is crucial because these values provide an index of host–guest binding forces. CDs can also form exclusion complexes where the CDs are bound to the guest through a H-bond network. For instance, the complexation of [PMo12O40] anion by β- and γ-CD results in

• complexation of endogenous substances are of potential interest for many applications. Biomolecule/cyclodextrin inclusions complexes Native and modified CDs can be used to complex certain chemicals produced naturally present in cells and tissues (i.e., endogenous substances). Indeed, CDs are able to form

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• complexation. In that way, it was possible to decorate CDVs with carbohydrates [32][33], with peptides [34], and also with DNA [35]. Moreover CDVs were also shown to form very dense membranes in combination with phospholipids and cholesterol [36]. Previous studies also showed promising results for PDT

• the presence of the aggregated form of AdSq (see Figure S2 in Supporting Information File 1). The fluorescence spectra show a saturation of the intensity maximum for a concentration of 60 µM CDV. Assuming that the accessible concentration of cyclodextrin available for the complexation of guest is only

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• decreased with the addition of competitive molecules, indicating that complexation between CD-CTA and the monomer plays an important role in determining polymerization rate. Results and Discussion Preparation of α-CD-CTA We designed a CTA reagent with α-CD or β-CD. Figure 1 illustrates the preparation of α

• inhibiting the molecular recognition of α-CD, the inclusion complexation ratio between the monomer and α-CD-CTA was decreased, which lead to lower yields and higher molecular weight of the resulting polymers due to preceding free radical polymerization. In the reaction of AAm monomer, which has a low

Synthesis, dynamic NMR characterization and XRD studies of novel N,N’-substituted piperazines for bioorthogonal labeling

• Constantin Mamat,
• Marc Pretze,
• Matthew Gott and
• Martin Köckerling

Beilstein J. Org. Chem. 2016, 12, 2478–2489, doi:10.3762/bjoc.12.242

• explored in terms of their NMR and complexation behavior. However, unsymmetrically substituted piperazines are rarely investigated [12][13]. N,N’-Unsymmetrically functionalized piperazines are the basis of the development of our new building blocks. In this case, one of the nitrogen atoms is used for the

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• very strong complexes with not only the native but with the substituted CDs, too. Although a solvent-free synthetic method does not solve the problem of complexation but the reduced amount of reagents can simplify the purification. Heptakis(6-azido-6-deoxy)-β-CD is the precursor to per-6-amino-β-CD

• /halogen molar ratios did not change such extent (Table 1). This can be explained satisfactorily by the complexation of the leaving group which might have high affinity to the CD cavity [3][25][26] preventing its departure from the reaction centres resulting in steric blocking. While the halogen → azide

• . The resulting crude mixture was only partially soluble in methylene chloride and MeOH precipitation gave a difficult-to-filter product, which still contained at least one mole of complexed DDS. This complexation resulted in not only technical difficulties, but also confounded the removal of impurities

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

• Ángel Cantín,
• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

• acid sites in the solids We have prepared Ti-Beta [31], Sn-Beta [32] and Al-Beta (Si/Al = 50) [33] considering that Lewis acid catalyzes the DAR [1]. This effect is known to occur by complexation of the carbonyl group of the dienophile with the Lewis acid that increases the electron deficiency of the

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• material was initially activated by NaHCO3. Discussion To explain the adsorption performance of polyBTCA-CD, a chemisorption mechanism involving several interactions can occur including ion exchange, electrostatic interactions, inclusion complexation and/or precipitation [3][12][13][14][15][16]. The

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• mode of complexation of L with Cu2+, 1H NMR titrations were carried out (Figure 7). Upon the initial addition of Cu2+ into the CD3CN solution of L, signals related to OH phenolic groups (Hb) and amidic protons (Ha) were first broadened and then finally disappeared. Furthermore, the signals of Ar–CH2

• (Hd, He) and –O–CH2 (Hf) porotons, which are close to the binding site of receptor L were affected and downfield shifted by the complexation of L with Cu2+. A detailed analysis of the 1H NMR spectra reveals the significant changes of almost all the other proton signals in the ligand. For instance, the

• indicated that the synthesized chemosensor L has a lower LOD and a higher Ka in comparison with other chemosensors, which shows a stable and selective complexation with Cu2+. Conclusion In this study, the amidoflourene-appended calix[4]arene 1,3-diconjugated L was synthesized as an efficient colorimetric

Cp₂TiCl/D₂O/Mn, a formidable reagent for the deuteration of organic compounds

• Antonio Rosales and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

• cyclic voltammetry, theoretical calculations and electro-paramagnetic resonance techniques studies [28][34]. These results are in agreement with the previously reported results by Wood et al. [35] and Renaud et al. [36] describing the effect of complexation with a Lewis acid on the strength of the O–H

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• contribute significantly to their structural and physical properties as well as to their biological activity [1][2][3]. Heterocycles can for example be involved in cation complexation as known for ionophoric polyethers or introduce conformational rigidity into a molecule, which is crucial for target binding

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• aryl halide, an associative mechanism for the complexation of carbon monoxide on the d8 square planar intermediate would occur prior to the key migratory insertion step. In the complex, the aryl group would be oriented perpendicularly to the plane to minimise steric interactions thus placing the ortho

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• from the secondary phosphines by deprotonation with KH in refluxing THF. The NeoPHOX ligands, which were obtained by this route in high overall yield, proved to be air and moisture stable and could be obtained in analytically pure form by simple filtration through silica gel [19]. Complexation with [Ir

• –76% yields (Scheme 7). From these ligands a library of iridium catalysts was prepared by complexation with bis(1,5-cyclooctadiene)diiridium(I) dichloride, followed by anion exchange with NaBArF. Comparative hydrogenation studies with iridium catalysts derived from 1st and 2nd generation NeoPHOX

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• reagents, also used as solvent, were cyclopentane, cyclohexane and cycloheptane. Two factors are noteworthy in this work. Unlike the carboxamide complexes (R)-18 and (S)-18 previously reported by Doyle and coworkers (Table 2), where the complexation of the chiral ligand to rhodium atoms occurs through the