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

• 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

• treated with the α-CD-siloxane derivatives. The solutions were stirred overnight and analyzed by 1H NMR and 2D ROESY NMR. As seen in Figure 2, 1H NMR spectra of pure ferrocene and the resulting complexes are compared with regard to the proton signals of the cyclopentadienyl rings of the ferrocene. In the

• strands can be linked with each other through the host–guest interactions of the terminal α-CD units and pure ferrocene without the need for covalent bonds. In order to complete the characterization of these host–guest interactions of the novel compounds, they were also examined by 2D ROESY NMR

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

• )-interactions. The supramolecular structures were characterized by 1H NMR-ROESY spectroscopy, dynamic light scattering, UV–vis spectroscopy, fluorescence spectroscopy, and asymmetric flow field-flow fractionation. By adding potassium adamantane-1-carboxylate, the thiazol dye is displaced from the CD-cavity and

• and β-CD was proven by 1H NMR rotating-frame Overhauser effect spectroscopy (ROESY) (Figure 1). NOE correlation signals of the β-CD cavity protons between 4 and 3.5 ppm and the aromatic protons of the pyridine moiety 8.6–7.4 ppm were observed, clearly proving the formation of complexes. However, no

• , OH), 3.75–3.53 (br, 28H, CH), 2.22 (br, 3H, CH3) ppm; IR: 3301 (OH), 2923 (C-H), 1653 (C=C), 1548 (ring vibr.), 1329 (OH), 1153 (COH), 1078 (COC), 1027 (COH) cm−1; MS (MALDI–TOF) (acetonitrile/water 1:10): m/z = 1412 [M + Na]+. 1H NMR-ROESY spectrum of the modified CD 3. UV–vis spectrum of 3 (4 × 10

Influence of cyclodextrin on the solubility and the polymerization of (meth)acrylated Triton^® X-100

• Melanie Kemnitz and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2176–2183, doi:10.3762/bjoc.8.245

• a few minutes (Scheme 1). In the solid state, the complex formation could be proved by FTIR, as the ether-band shifted from 1102 to 1033 cm−1. By using 2D-ROESY NMR, the interactions between the inner protons H-3 and H-5 of 2,6-dimethyl-β-cyclodextrin (DIMEB-CD) and the protons of the tert-octyl and

• tert-octyl group were broader after the polymerization. The 2D-ROESY spectrum indicates that the complex was still intact after the polymerization (Supporting Information File 1, Figure S3). DSC measurements of the dried samples indicate a high influence of RAMEB-CD. The Tg value was found to be about

• . 2D-ROESY and 1H NMR measurements were performed on a Bruker AVIII-300 spectrometer at 300.13 MHz. The δ scale relative to tetramethylsilan was calibrated to the solvent value δ 7.26 ppm for CDCl3 and δ 4.79 ppm for D2O. Infrared (IR) spectra were determined on a Nicolet 6700 FTIR spectrometer

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• combined successfully with mono-6-azido-6-deoxy-β-cyclodextrin (6) in a click-type reaction to give copolymer 7 (Scheme 1). ROESY measurements show some weak interaction of the protons of β-CD with the protons of the ferrocene (Fc) moiety and the tert-butyl-moiety (Supporting Information File 1

• with excess potassium adamantylcarboxylate overnight. The residue was then filtered off and the remaining filtrate was used for measurement. NMR experiments (1H, ROESY) were performed on a Bruker Avance DRX 200 spectrometer operating at 200.13 or 500 MHz for protons with DMSO-d6 or CDCl3 99.9% as

• complex with adamantylcarboxylate (•••). Synthetic pathway to the desired polymer 7. Summary of peak potentials acquired by cyclic voltammetry (ferrocenyl oxidation or reduction/phenol oxidation or reduction). Supporting Information The Supporting Information features a copy of the ROESY NMR spectrum of

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

• proved by use of 2D ROESY NMR spectroscopy (Supporting Information File 1). The correlation signals between the protons of the RAMEB-CD cavity and the aromatic protons of the azo dye were observed. However, the correlation signals between the RAMEB-CD cavity and the methyl protons of the N,N

• -responsive behavior in aqueous solution was analyzed by absorption and cloud-point measurements. In addition, the influences of RAMEB-CD on both effects were investigated. The intermolecular interaction between the dye end group and RAMEB-CD was proven by absorption and 2D ROESY NMR experiments. Furthermore

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• solubility of 5 at room temperature (about 25 °C). However, the turbid dispersion becomes completely clear by the addition of methylated β-cyclodextrin (Me2-β-CD). This means that a water-soluble inclusion complex 7 of 5 with Me2-β-CD is formed (Figure 3). The 2D ROESY NMR spectrum of 7 indicates the

• . Optical transmittance of aqueous solutions (c = 20 mg/mL) of 3, 6 und 8 during heating. 2D ROESY NMR spectrum of a 5/Me2-β-CD deuterated water solution. Temperature-dependent transparency measurements of aqueous solution of the supramolecular complex 7 (c = 20 mg/mL in water). Mechanism of free radical

Impact of cyclodextrins on the behavior of amphiphilic ligands in aqueous organometallic catalysis

• Hervé Bricout,
• Estelle Léonard,
• Christophe Len,
• David Landy,
• Frédéric Hapiot and
• Eric Monflier

Beilstein J. Org. Chem. 2012, 8, 1479–1484, doi:10.3762/bjoc.8.167

• biphenyl moiety. Additionally, the phosphane nonlinear geometry resulting from the zig-zag diazo structure also disfavored the recognition process between the phosphane and the CD cavity. The existence of phosphaneCD supramolecular complexes was confirmed by using a 2D NMR T-ROESY sequence sensitive to

• dipolar contacts between the CD host and the phosphane guest. Correlations were detected on T-ROESY spectra of stoichiometric mixtures of RAME-β-CD and phosphanes 1–4. However, a clear assignment of the CD and phosphane protons could not be properly made due to a severe broadening of the NMR signals (ESI

• , we are currently widening the scope of the CD/amphiphilic phosphane interaction in other aqueous-phase organometallic reactions. Water-soluble phosphanes 1–4. 2D T-ROESY NMR spectrum of a stoichiometric mixture of β-CD and 4 (3 mM each) in D2O at 20 °C. Effect of increasing concentrations of β-CD

Partial thioamide scan on the lipopeptaibiotic trichogin GA IV. Effects on folding and bioactivity

• Marta De Zotti,
• Barbara Biondi,
• Cristina Peggion,
• Matteo De Poli,
• Haleh Fathi,
• Simona Oancea,
• Claudio Toniolo and
• Fernando Formaggio

Beilstein J. Org. Chem. 2012, 8, 1161–1171, doi:10.3762/bjoc.8.129

• performed in CD3CN solution for all of the ψ[CS-NH]-containing [Leu11-OMe] trichogin GA IV analogues. The proton resonances were fully assigned following the Wüthrich procedure [64]. Regions of the ROESY spectrum acquired for ψ[CS-NH]9 are shown in Figures 5–7. The patterns of NH(i)–NH(i+1) connectivities

• (e.g., Figure 5) strongly suggest the onset of an overall helical structure for all analogues. More relevant 3D-structural information was extracted from the fingerprint regions of the ROESY spectra (e.g., Figure 6 and Figure 7), which show evidence for dα(β),N (i, i+2), (i, i+3), and (i, i+4) medium

• related ROESY spectrum (Table S-I, Supporting Information File 1), were used in the SA protocol. The structures possessing violations to the NOE restraints lower than 0.5 Å were selected out of the 150 generated structures. The superposition of the 18 structures with a total energy <144 kcal/mol is shown

Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel

• Elena A. Khatuntseva,
• Vladimir M. Men’shov,
• Alexander S. Shashkov,
• Yury E. Tsvetkov,
• Rodion N. Stepanenko,
• Raymonda Ya. Vlasenko,
• Elvira E. Shults,
• Genrikh A. Tolstikov,
• Tatjana G. Tolstikova,
• Dimitri S. Baev,
• Vasiliy A. Kaledin,
• Nelli A. Popova,
• Valeriy P. Nikolin,
• Pavel P. Laktionov,
• Anna V. Cherepanova,
• Tatiana V. Kulakovskaya,
• Ekaterina V. Kulakovskaya and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2012, 8, 763–775, doi:10.3762/bjoc.8.87

• -glucuronic acid (D-GlcA). Similar investigation of compound 2 revealed the same sugar composition as for compound 1. The structures of both compounds 1 and 2 were confirmed on the basis of their 1H NMR, 13C NMR, APT, COSY, TOCSY, ROESY, HSQC, and HMBC spectra. In accordance with the earlier reports [18] on

• triterpene aglycon and showed the positions of the substitutions within the oligosaccharide fragments (Table 1 and Table 2). The ROESY spectra (identical for compounds 1 and 2) disclosed the sequence of the residues in two oligosaccharides and their location at the C-3 and C-28 of the aglycon. Thus, the

• . Esterification of the position 1 of Fuc (residue d) with the carboxy group of the triterpene was unambiguously shown by the high-field shift of C-1 (94.4 ppm), being indirectly confirmed with the long-range correlation peak in the ROESY spectra 16Agl/3d. The sequence of the other residues was disclosed from the

Enantioselective supramolecular devices in the gas phase. Resorcin[4]arene as a model system

• Caterina Fraschetti,
• Matthias C. Letzel,
• Antonello Filippi,
• Maurizio Speranza and
• Jochen Mattay

Beilstein J. Org. Chem. 2012, 8, 539–550, doi:10.3762/bjoc.8.62

• was pointed out from previous NMR experiments [44]: In CDCl3 solution the neutral homochiral aggregate is significantly more stable than the heterochiral one, while NMR 1D ROESY results indicated that the dipeptidic guest is not located in the cavity of the host, but that the interaction that is

Chiral recognition of ephedrine: Hydrophilic polymers bearing β-cyclodextrin moieties as chiral sensitive host molecules

• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1516–1519, doi:10.3762/bjoc.7.177

• -containing polymer. The supramolecular structures obtained by complexation of ephedrine and cyclodextrin were verified by 2-D ROESY NMR measurements. Dynamic light scattering showed clear differences in the mean coil size. Keywords: chiral recognition; cyclodextrins; ephedrine; host–guest interaction

• -exclusion chromatography (SEC), dynamic light scattering (DLS) and turbidity measurements. To confirm the formation of the proposed host–guest structure of β-cyclodextrin and ephedrine in principle, 2-D ROESY NMR spectroscopy was performed at room temperature with β-CD in excess. Thus the correlation

• recognition with a CD-containing polymer complexed with (+)- or (−)-ephedrine. The supramolecular structures obtained by complexation of ephedrine and CD were detected by 2-D ROESY NMR measurements. Dynamic light scattering exhibited clear differences of 5 nm in the mean coil size, between the two enantiomers

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• corresponding Job plot confirms the 1:1 complex between 1h and SMD (Supporting Information File 1). Moreover, complex formation was confirmed by a weak NOE effect, as determined by ROESY NMR experiments, between the protons in the ortho position of the phenyl group of the mandelate and the bis(trifluoro)phenyl

Chiral recognition of macromolecules with cyclodextrins: pH- and thermosensitive copolymers from N-isopropylacrylamide and N-acryloyl-D/L-phenylalanine and their inclusion complexes with cyclodextrins

• Sabrina Gingter,
• Ella Bezdushna and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 204–209, doi:10.3762/bjoc.7.27

• between the copolymers and CD, which was added in excess, the corresponding monomers 2D and 2L were used as models to prove complexation. Thus, 2D ROESY NMR spectroscopy was performed to show the correlation between the protons of the β-CD and the protons of the guest 2D. Figure 1 indicates as an example

• concluded, that the complex composition with 2D or 2L has a stoichiometry of 1:2. To assure for further investigations that the complexation also takes place in the copolymer, additional ROESY experiments were carried out (Figure 2). The NMR experiments clearly show that the complexation takes place in

• (dd, J = 365.4 Hz, 367.1 Hz, 9H) FT-IR (diamond cm−1): ν = 3288 (NH amide I), 2970, 2932, 1713 (C=O), 1641 (NH amide II), 1538 (Ar), 1457, 1386, 1256, 1172, 1095, SEC (DMF): Mn (3L) 16000 g/mol; PDI (3L) 3.6, Mn (3D) 7000 g/mol, PDI (3D) 2. 2D NMR ROESY spectrum of monomer 2D with RAMEB-CD. 2D NMR

Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water

• Helmut Ritter,
• Beate E. Mondrzik,
• Matthias Rehahn and
• Markus Gallei

Beilstein J. Org. Chem. 2010, 6, No. 60, doi:10.3762/bjoc.6.60

• (cp) + 3.52 ppm (2) in 1H1H ROESY-NMR spectrum. The LCST of the copolymer in water was slightly increased from 17 °C to 19 °C (Figure 4) after the addition of cyclodextrin. Conclusion It can be concluded from the experiments described above that vinylferrocene can be easily polymerized in water after

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• inclusion complexes with aromatic guest molecules [54] and Cu(II) ion [56]. Additionally, van Well et al. have described a cyclization/cleavage strategy for solid phase synthesis of cyclic trimers and tetramers containing pyranoid δ-SAAs (Scheme 2) and reported their structural analysis from ROESY data in

• -oligomers of mannose- and glucose-derived furanoid SAAs [58] in order to constrain their conformational degrees of freedom and to induce desirable structural elements essential for their biological activities, such as tubular structures for transporting ions or molecules across membranes. Detailed ROESY

• can give rise to defined secondary structures or be exploited in molecular recognition. Conformational studies by temperature coefficient measurements and ROESY experiments showed that thioureidodisaccharides adopt the Z,E conformation at N–(C=S) bonds, which is stabilised by intramolecular hydrogen

An efficient partial synthesis of 4′-O-methylquercetin via regioselective protection and alkylation of quercetin

• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang,
• Jian-Ping Yang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2009, 5, No. 60, doi:10.3762/bjoc.5.60

• Frame Overhauser Effect Spectroscopy (ROESY) (Figure 2). A cross-peak observed in the ROESY spectrum between δ 3.98 (C4′-OCH3) with 6.96 (C5′-H) confirmed that the position of the methyl group was at C4′-O (Figure 2). This corresponds to the one-dimensional (1D)-nuclear Overhauser effect (NOE) reported

• +H]+, 339 [M+Na]+; Anal. calcd. for C16H12O7: C, 60.76; H, 3.82. Found: C, 60.71; H, 3.87. Structures of quercetin and methylated metabolites. ROESY correlations of compound 2. Synthesis of 4′-O-methylquercetin (2, tamarixetin). a) Ph2CCl2, Ph2O, 175 °C, 30 min, 86%; b) MOMCl, K2CO3, acetone, reflux