Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

• Silvia Bernardi,
• Paola Fezzardi,
• Gabriele Rispoli,
• Stefania E. Sestito,
• Francesco Peri,
• Francesco Sansone and
• Alessandro Casnati

Beilstein J. Org. Chem. 2014, 10, 1672–1680, doi:10.3762/bjoc.10.175

• Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy 10.3762/bjoc.10.175 Abstract Four novel calix[4]arene-based glycoclusters were synthesized by conjugating the saccharide units to the macrocyclic scaffold using the CuAAC reaction and using long and hydrophilic ethylene glycol spacers

• efficient multivalent ligands for a series of pathological lectins. For instance, cholera toxin is bound rather efficiently by calix[4]arene [16] and calix[5]arene [17] derivatives, while examples of Pseudomonas aeruginosa LecB binding were reported with galactosylcalixarenes blocked in different

• convergent synthetic approach. This approach was based on the connection, by CuAAC reaction, of the azido-terminating tetraacetylgalactose 5 [40][41] to calix[4]arene 8 decorated at the upper rim with alkyne terminating chains (Scheme 1). In order to introduce the alkyne units at the upper rim of the

Orthogonal dual thiol–chloroacetyl and thiol–ene couplings for the sequential one-pot assembly of heteroglycoclusters

• Michele Fiore,
• Gour Chand Daskhan,
• Baptiste Thomas and
• Olivier Renaudet

Beilstein J. Org. Chem. 2014, 10, 1557–1563, doi:10.3762/bjoc.10.160

• in our group to prepare tetravalent structures displaying two sugars either in 2:2 or 3:1 relative proportions [20]. In the meanwhile, the group of A. Dondoni has developed a sequential orthogonal TEC in combination with CuAAC for grafting two different sugar motifs on calix[4]arene scaffold [21

Low-generation dendrimers with a calixarene core and based on a chiral C₂-symmetric pyrrolidine as iminosugar mimics

• Marco Marradi,
• Stefano Cicchi,
• Francesco Sansone,
• Alessandro Casnati and
• Andrea Goti

Beilstein J. Org. Chem. 2012, 8, 951–957, doi:10.3762/bjoc.8.107

• , Parco Area delle Scienze 17/A, I-43124 Parma, Italy 10.3762/bjoc.8.107 Abstract The preparation of low-generation dendrimers based on a simple calix[4]arene scaffold by insertion of the iminosugar-analogue C2-symmetric 3,4-dihydroxypyrrolidine is described. This methodology allows a rapid incorporation

• dendrimers, based on the C2-symmetric (3S,4S)-3,4-dihydoxypyrrolidine (1) unit, to a simple calix[4]arene scaffold (Figure 1). This allows a rapid increase of the valency of the iminosugar dendrimer in a reduced volume. The C2 symmetry of pyrrolidine 1, its ready accessibility from the “chiral pool” (L

• strategy. A convergent synthetic approach was chosen for the conjugation of pyrrolidine 4 and pyrrolidine-based dendron 5 (see Scheme 1) to the calix[4]arene core, via intermediate 11, in order to obtain iminosugar-based calixarene-dendrimers 2 and 3 (see Scheme 2). The starting calixarene used in this

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• inversion in CDCl3 was <38 kJ mol−1, in contrast with 66 kJ mol−1 for the calix[4]arene analogue. To freeze the oxacalix[3]arene conformer, through-the-annulus rotation must be prevented. This can be achieved by the introduction of sufficiently large groups on the lower rim of the macrocycle. Upper-rim

• CH2Cl2 indicated that the n-butyl ether derivative 10 showed a high affinity for n-BuNH3+ (82% E) as postulated by the authors, because both host and guest possess the same C3-symmetry [24]. Ethyl ester 12a was more efficient at extracting n-BuNH3+ picrate from water into CH2Cl2 than its calix[4]arene

Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene

• Conrad Fischer,
• Wilhelm Seichter and
• Edwin Weber

Beilstein J. Org. Chem. 2011, 7, 1602–1608, doi:10.3762/bjoc.7.188

• the lower-rim site as well as tert-butylated or non-tert-butylated upper-rim positions. Whereas this reaction fails for symmetric calix[4]arene ethers with alkoxy residues greater than methoxy, the carboxylation of mixed methoxy-propoxy calixarene ethers is possible. In connection with this, several

• the lithiation of differently upper- and lower-rim-modified calix[4]arenes, allowing us to draw helpful conclusions about the necessary structural requirements for the bridge lithiation and subsequent substitution of a basic calix[4]arene. Results and Discussion Since the calixarene 2 is known to

• undergo lithiation and subsequent carboxylation to yield the carboxylic acid 6 [4], we became interested in the question of whether the upper-rim unsubstituted calix[4]arene 1, as well as higher ether homologues, such as 3 and 4, can also be used for this reaction (Scheme 1). While the upper-rim site

Calix[4]arene-click-cyclodextrin and supramolecular structures with watersoluble NIPAAM-copolymers bearing adamantyl units: “Rings on ring on chain”

• Bernd Garska,
• Monir Tabatabai and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 784–788, doi:10.3762/bjoc.6.83

• 5,11,17,23-tetra-tert-butyl-25,27-dipropargylether-26,28-hydroxy-calix[4]arene (calix[4]arene-dipropargylether) (2) onto 6I-azido-6I-deoxycyclomaltoheptaose (3) under microwave assisted conditions. The coupling was proven by MALDI-TOF mass spectrometry, 1H NMR and IR-spectroscopy. The pH dependent

• supramolecular complex formation with poly(NIPAAM) bearing attached adamantyl units was investigated by dynamic light scattering (DLS) and turbidity measurements. Keywords: β-cyclodextrin; calix[4]arene; click chemistry; poly(NIPAAM); Introduction Supramolecular interactions of macrocycles with different types

• calixarenes and β-CD via click reaction and their application in the field of supramolecular chemistry has not yet been reported. Herein, we describe the synthesis and complexation behavior of a dual type calix[4]arene-click-cyclodextrin (4) receptor by the cycloaddition of a dipropargylether of calix[4]arene

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

Synthesis and properties of calix[4]arene telluropodant ethers as Ag⁺ selective sensors and Ag⁺, Hg²⁺ extractants

• Yang Lu,
• Yuanyuan Li,
• Song He,
• Yan Lu,
• Changying Liu,
• Xianshun Zeng and
• Langxing Chen

Beilstein J. Org. Chem. 2009, 5, No. 59, doi:10.3762/bjoc.5.59

• performances have not been described to date. Aiming to construct receptor molecules which are sensitive to transition metal ions, a large number of calix[4]arene derivatives containing N, S, Se and P(III) atoms as soft donors have been prepared and their sensor properties have also been evaluated by ion

• atoms on the lower rims linked via methylene groups respectively, and study their Ag+-selective behavior by electromotive force measurements of polymer membrane electrodes. Results and Discussion Synthesis and conformations of calix[4]arene 6–8, 10 and 12 As shown in Scheme 1, the calix[4]arenes 6–8

• were synthesized in yields between 92% and 97% by the reaction of the preorganized cone conformation calix[4]arene dibromides 3–5 [54][55] with the sodium salt of phenyltellurate, which was prepared in situ by the reaction of diphenylditelluride with sodium borohydride in the presence of NaOH at the

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• have been synthesized by O-alkylation of the parent calix[4]arene. The compounds are formed in the cone conformation. They are soluble in several fluorous solvents and show promise for use in sensing, selective extractions and other applications. Keywords: calixarene; fluorous; hydrofluoroethers

• provided the X-ray structure in Figure 2. Two crystallographically independent calixarene molecules made up the asymmetric unit, each molecule having a similar calix[4]arene ring and differing in the number and location of the gauche bonds in the (perfluorooctyl)propyl chains. The asymmetric unit also

• molecular recognition interactions. Calix[4]arene in cone conformation. Full (top), top (bottom left)a, and side (bottom right)a views of 5; afluorous chains omitted for clarity. Preparation of 3a and 3b. Preparation of 4 and 5. Preparation of 6. Preparation of 8 and 9. Solubility of 3a and 3b in fluorous