Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• spectroscopy. The magnetic interaction of the monomer with the cavity of RAMEB-CD is obvious in the 2D ROESY NMR spectra as shown in Figure 1 (marked areas). Principally, cyclodextrins and their derivatives are able to discriminate enantiomeric compounds [9][10]. Such chirality recognition is provable with 1H

Effect of cyclodextrin complexation on phenylpropanoids’ solubility and antioxidant activity

• Miriana Kfoury,
• David Landy,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2014, 10, 2322–2331, doi:10.3762/bjoc.10.241

• , France ULCO, UCEIV, F-59140 Dunkerque, France 10.3762/bjoc.10.241 Abstract The complexation abilities of five cyclodextrins (CDs) with seven phenylpropanoids (PPs) were evaluated by UV–visible spectroscopy, phase solubility studies and molecular modeling. Formation constants (Kf), complexation

• efficiency; cyclodextrins; formation constant; phenylpropanoids; solubility; Introduction Phenylpropanoids (PPs), produced through the shikimic acid pathway, are one of the major groups of natural compounds. They could be found in a wide variety of plants (clove, anise, basil, tarragon, fennel, parsley

• limited water solubility, stability and poor bioavailability [8][9]. Thus, their encapsulation may enhance their apparent solubility without losing their structural integrity and bioactivity. During the past years, cyclodextrins (CDs) have been widely used as encapsulating agents to enhance the solubility

End group functionalization of poly(ethylene glycol) with phenolphthalein: towards star-shaped polymers based on supramolecular interactions

• Carolin Fleischmann,
• Hendrik Wöhlk and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2263–2269, doi:10.3762/bjoc.10.235

• combination of CRP with supramolecular complex formation, e.g., by the use of cyclodextrins (CDs) [6][7][34]. The most important representatives of these cyclic oligosaccharides with respect to industrial applications consist of six (α-CD), seven (β-CD) and eight (γ-CD) glucopyranose units and have a cone

• moieties serving as the dipolarophil in a subsequent treatment with β-cyclodextrin azide. Thereby, a dipentaerythritol derivative carrying six cyclodextrins (DPE-CD) that are covalently attached through triazole rings was obtained. Mixing of mPEG-PP and DPE-CD resulted in the formation of stable complexes

Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

• Nattawut Yotapan,
• Chayan Charoenpakdee,
• Pawinee Wathanathavorn,
• Boonsong Ditmangklo,
• Hans-Achim Wagenknecht and
• Tirayut Vilaivan

Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224

• confirmed that the Nile red label is buried well within the hydrophobic pocket of the bulged duplexes and therefore not available to form an inclusion complex with the cyclodextrins [17]. Less pronounced shifts were observed with complementary and mismatched duplexes (2 and 4 nm, respectively) upon the

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• granular morphology with a lower dispersity supported by a smaller roughness exponent compared with the non-rotaxane counterpart. Keywords: cyclodextrins; energy band gaps; fluorescence lifetimes; persilylated cyclodextrins; supramolecular encapsulation; surface morphology; Introduction Semiconducting π

• used to synthesize copolymers with smaller electrochemical and optical band gaps, so that materials with improved electronic and optical properties can be obtained [17]. The construction of mechanically interlocked molecules such as rotaxanes and polyrotaxanes with native cyclodextrins (CDs) as

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• of CF in pharmaceutical preparations (Figure 9) [29]. However, solutions containing both phosphate buffer and CF have been found to influence the photodegradation of RF by inhibiting the photoreduction pathway and enhancing the photoaddition pathway [35]. Different types of cyclodextrins have been

• studied for complexation with RF to achieve its stabilization [111][112][113][114][115][116][117]. In a comparative study of complexation between α- and β-cyclodextrins with RF, β-cyclodextrin was found to form more stable inclusion complexes with RF [116]. The formation of strong and stable inclusion

• complexes of RF with β- and γ-cyclodextrins have also been observed in other studies [111][112][113][114][115]. Such β-cyclodextrin complexes are suitable for fluorescent compounds for which the fluorescence intensity is influenced by the presence of cyclodextrins [113]. A non-inclusion complexation between

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• ]. There is also promise being seen with organic hydroxylated and oxygenated compounds such as cellulose triacetate [87], cyclodextrins [88], amorphous poly(lactic acid) and glucopyranoside [89] (Table 2, compounds 25–28) as well as polymers with incorporated ether linkages [87]. Beckman and Enick et al

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• PEGylation. Hydrogels with supramolecular structures have been obtained by inclusion complexation of the PEG grafted dextrans with α-cyclodextrins. The unique thermoreversible sol-transition properties of the gels were considered interesting for drug delivery applications [65]. Conclusion The advantage of

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

• Martin Popr,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

• methylation. The majority of the presented reactions are very straightforward with a simple work-up, which avoids the need of chromatographic separation. Thus, these reactions are suitable for the multigram-scale production of monosubstituted cationic CDs. Keywords: cationic; cyclodextrins; monosubstitution

• ; regioselectivity; tetraalkylammonium derivatives; Introduction Cyclodextrins (CDs) are cyclic oligosaccharides with the shape of a hollow truncated cone, first described in 1891 by Villiers [1]. Naturally occurring CDs are named α-, β- and γ-cyclodextrin and are composed of 6, 7 or 8 D-glucopyranose units

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• shallow binding sites that bind non-polar substrates via dispersive interactions. Hence, we wanted to take this approach one step further by using β-cyclodextrins as another class of macrocyclic compounds that are very well-known for their excellent recognition properties towards non-polar substrates [25

• cyclodextrins cannot interact with a substrate in a cooperative fashion (off-state) but change their conformation to a closed syn-conformation (on-state) upon binding of a suitable transition metal ion or complex as an effector. This is shown schematically for a 4,4’-substituted bipyridine-based receptor in

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

• Malamatenia D. Manouilidou,
• Yannis G. Lazarou,
• Irene M. Mavridis and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 774–783, doi:10.3762/bjoc.10.73

• and animals in vivo have been demonstrated [6]. Cyclodextrins (CDs, Scheme 1c), are cyclic oligomers of glucopyranose that act as hosts to hydrophobic molecules in aqueous environment [9][10]. CDs have been recognized as potent drug solubilizers and transporters through biological barriers with

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• functionalization is supported by 1H NMR-, SEC-, FTIR- and MALDI–TOF measurements. Keywords: chain-transfer polymerization; cyclodextrins; end-group functionalization; host–guest interaction; lower critical solution temperature (LCST); poly(N,N-diethylacrylamide); Introduction Supramolecular chemistry was first

• interactions in living systems [3][4]. Since then, the field of self-assembly through molecular recognition has attracted much attention also in the design of smart materials. In this context, cyclodextrins (CD) are of interest as ring shaped host molecules, e.g., for the design of stimuli-responsive hydrogels

N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

• Julian Fischer,
• Simon Millan and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2834–2840, doi:10.3762/bjoc.9.318

• adequate phase transfer catalysts and the cyclodextrin–guest complexes were characterized by 1H NMR and 2D NMR ROESY spectroscopy. Finally, the curing properties of the diepoxide with lysine-based α-amino-ε-caprolactam were analyzed by rheological measurements. Keywords: alkylation; cyclodextrins; epoxy

• concentrations [10][11][12]. An alternative route is a two-step reaction via N-allylation and further Prilezhaev epoxidation with peroxides [13][14][15]. The solubility of hydrophobic reactants in water can be increased significantly by cyclodextrins (CD) and thereby the use of organic solvents can be reduced

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• [5]. The Tc can be influenced for example through copolymerization with hydrophobic or hydrophilic comonomers and further through supramolecular interactions of these comonomers with cyclodextrins (CD) [6][7][8][9][10]. Generally, CDs are water soluble and their ability of forming inclusion complexes

Structure elucidation of β-cyclodextrin–xylazine complex by a combination of quantitative ¹H–¹H ROESY and molecular dynamics studies

• Syed Mashhood Ali,
• Kehkeshan Fatma and
• Snehal Dhokale

Beilstein J. Org. Chem. 2013, 9, 1917–1924, doi:10.3762/bjoc.9.226

• which a guest is encapsulated into the internal cavity of a larger host molecule. The most widely used hosts are cyclodextrins (CDs) which are crystalline, homogeneous and non-hygroscopic substances composed of α-1→4 linked glucose units. The outside surface of CDs is hydrophilic while the interior of

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• -to-head dimer. The degree of complexation of coumarin could be increased by employing the salting out effect. Keywords: acenaphthylene; anthracene; coumarin; cyclodextrins; photodimerization; quantum yield; stereoselectivity; Introduction Photochemical reactions have been considered highly

• smallest possible templates for the control of photoreactions. Such a host provides a well-defined nano environment, a so-called molecular reaction vessel [6], which can catalyze and direct particular transformations. Calixarenes [7], cucurbiturils [8][9], and cyclodextrins (CDs) [10][11][12][13][14][15

Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

• Helmut Ritter,
• Berit Knudsen and
• Valerij Durnev

Beilstein J. Org. Chem. 2013, 9, 1278–1284, doi:10.3762/bjoc.9.144

• terminally substituted oligo(dimethylsiloxanes) bearing α-cyclodextrins (α-CD) as host end groups for the cyclopentadienyl rings of ferrocene. This double complexation of unsubstituted ferrocene leads to a supramolecuar formation of the siloxane strands. Structural characterization was performed by the use

• verified by the shifts of the protons in the 1H NMR spectra and in the correlation signals of the 2D ROESY NMR spectra. Keywords: cyclodextrins; ferrocene; host–guest systems; polysiloxanes; supramolecular chemistry; Introduction Polymers containing cyclodextrins (CD) covalently or supramolecularly

• cyclodextrin and ferrocene as a representative of metallocenes has been the subject of numerous works. Especially Takahashi and Harada were engaged in the analysis of ferrocene complexes with different cyclodextrins [5], which could be obtained in aqueous solution in high yields. In addition, the crystal

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

• Sophie Fourmentin,
• Anca Ciobanu,
• David Landy and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1185–1191, doi:10.3762/bjoc.9.133

• constants strongly increase with the amount of space filling of the CD cavity and the salt concentration. β-CD thioethers show a 3–10 times higher binding potential than native β-CD. Keywords: cyclodextrins; inclusion compound; molecular modelling; space filling; static headspace gas chromatography; vapor

Superstructures of fluorescent cyclodextrin via click-reaction

• Arkadius Maciollek,
• Helmut Ritter and
• Rainer Beckert

Beilstein J. Org. Chem. 2013, 9, 827–831, doi:10.3762/bjoc.9.94

• the elongated noncovalent polymeric structures collapse. Keywords: fluorescent dye; cyclodextrins; host–guest interaction; supramolecular polymer; Introduction Most small heterocyclic molecules show low fluorescence. However, as we reported earlier, substituted 4-hydroxythiazoles have a high

The β-cyclodextrin/benzene complex and its hydrogen bonds – a theoretical study using molecular dynamics, quantum mechanics and COSMO-RS

• Jutta Erika Helga Köhler and
• Nicole Grczelschak-Mick

Beilstein J. Org. Chem. 2013, 9, 118–134, doi:10.3762/bjoc.9.15

• mechanics; Introduction Cyclodextrins (CD) are a family of conical shaped cyclic oligosacharides consisting of 6–8 (or up to 10) glucopyranose units linked by α-(1→4) glycosidic bonds. At the narrower rim of the truncated cone (O6 side) there is one primary hydroxy group per glucose unit whereas at the

• wider rim there are two secondary hydroxy groups (O2/O3 side) [1]. Cyclodextrins have many possibilities of forming hydrogen bonds [2]: firstly, cyclodextrin monomers form some intramolecular hydrogen bonds or closed rings of hydrogen bonds at both rims of the cone; secondly, they form intermolecular

• -fluorophenol in α-CD [3]. The reactivity of aromatic guest molecules, radicals or excited states, was found to be altered because of complex formation with cyclodextrins [4]. Cyclodextrins form three types of dimers, O2/O3 to O2/O3, O2/O3 to O6, and O6 to O6. They can also associate to extended stacks in

Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

• Dyanne L. Cruickshank,
• Natalia M. Rougier,
• Raquel V. Vico,
• Susan A. Bourne,
• Elba I. Buján,
• Mino R. Caira and
• Rita H. de Rossi

Beilstein J. Org. Chem. 2013, 9, 106–117, doi:10.3762/bjoc.9.14

• ; hydrolysis; inclusion complex; Introduction Whereas cyclodextrins (CDs) have been employed for many years in the pharmaceutical industry to modify drug-delivery properties, the application of CD technology to the improvement of agrochemicals is a more recent innovation [1][2]. Nevertheless, very significant

• ]. In our recent reports on the interaction between CDs and the organophosphorus insecticide 1 we gave an account of the X-ray crystal structures and thermal decomposition profiles of two solid inclusion complexes between permethylated α- and β-cyclodextrins, hexakis(2,3,6-tri-O-methyl)-α-CD (TRIMEA

• solution containing 2% dioxane at 25 °C and in the presence of the native cyclodextrins α-CD, β-CD, γ-CD as well as the permethylated derivatives TRIMEA and TRIMEB, was performed [6]. This revealed weak host–guest association in the case of α-CD and insoluble complex formation in the case of the host

Theoretical study on β-cyclodextrin inclusion complexes with propiconazole and protonated propiconazole

• Adrian Fifere,
• Narcisa Marangoci,
• Stelian Maier,
• Adina Coroaba,
• Dan Maftei and
• Mariana Pinteala

Beilstein J. Org. Chem. 2012, 8, 2191–2201, doi:10.3762/bjoc.8.247

• methods consists of the complexation of antifungals with cyclodextrins and/or with soluble polymers. Propiconazole (PP) is a triazole derivative effective as a fungicide, with a broad spectrum, designed and launched by Janssen Pharmaceutics (Belgium). It is widely used in agriculture as a systemic foliar

• compared to unmodified PP. The inclusion compound based on β-cyclodextrin (β-CD) and PPH+ (further abbreviated as β-CD/PPH+) was preliminarily investigated in vitro, and its antifungal activity was reported [4]. Cyclodextrins (CDs) are macrocyclic oligosaccharides consisting of six to twelve glucopyranose

Cyclodextrin-based nanosponges as drug carriers

• Francesco Trotta,
• Marco Zanetti and
• Roberta Cavalli

Beilstein J. Org. Chem. 2012, 8, 2091–2099, doi:10.3762/bjoc.8.235

• nanoscale structural characteristics can be expected to provide many potential applications in the field of nanomedicine. Cyclodextrins [1][2][3] are nanometric biomaterials with a close relationship between molecular status and supramolecular properties. They are a class of cyclic glucopyranose oligomers

• and are synthesised by enzymatic action on hydrolysed starch. The main common native cyclodextrins are α, β and γ, which comprise six, seven and eight glucopyranose units, respectively. They have a characteristic toroidal shape, which forms a well-defined truncated cone-shaped lipophilic cavity

• . Cyclodextrins are able to include compounds whose geometry and polarity are compatible with that of their cavity. However, native cyclodextrins are not able to form inclusion complexes with certain molecules, such as hydrophilic or high-molecular-weight drugs. Moreover, β-cyclodextrin, the cheapest type, has

Cyclodextrin-induced host–guest effects of classically prepared poly(NIPAM) bearing azo-dye end groups

• Gero Maatz,
• Arkadius Maciollek and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 1929–1935, doi:10.3762/bjoc.8.224

• observed. Additionally, this azo-dye-end-group-labeled polymer was complexed with hyperbranched polyglycerol (HPG) decorated with β-CD to generate hedgehog-like superstructures. Keywords: azo-dye; cyclodextrins; end-group functionalization; host–guest interaction; supramolecular aggregation; Introduction

Influence of intramolecular hydrogen bonds on the binding potential of methylated β-cyclodextrin derivatives

• Gerhard Wenz

Beilstein J. Org. Chem. 2012, 8, 1890–1895, doi:10.3762/bjoc.8.218

• : binding constant; cyclodextrin; hydrogen bond; methylation; regioselective; Introduction Cyclodextrins (CDs) are a well-known class of organic hosts able to include various guests, preferably in aqueous solution [1][2][3]. Inclusion is mainly driven by hydrophobic and van der Waals interactions [4][5][6