Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• by calix[4]arene derivatives 7 bearing the guanidine groups at the upper rim and O-(2-ethoxyethyl) groups at the lower rim [80]. The role of the latter groups was to improve solubility to hydroxylic solvents and to rigidify the calixarene system into the so-called cone conformation. HPNP (1) was used

• hydroxy function on phosphorus (Scheme 8). Similar results were obtained on using diphenylmethane as a scaffold 8 (Figure 8) [81]. A cyclohexylidene or adamantylidene substituent on the methylene carbon moderately enhanced the catalytic activity. Interestingly, the calix[4]arene-based agent 7 catalyzed

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• type of anion is needed. (Thia)calix[4]arene derivatives are a favorable platform for the design of such structures [24][25][26][27][28][29][30][31][32][33][34]. Due to their macrocyclic nature and the possibility to modify them in three different ways (upper and lower rims and bridge fragments), they

• ][54][55][56][57]. Modified macrocycles with the amide fragments at the lower rim can form complexes with the anions by hydrogen bonds of the amide group with the guest. It was shown that (thia)calix[4]arene derivatives with urea and thiourea fragments at the lower rim can bind anions through hydrogen

Correction: Inherently chiral calix[4]arenes via oxazoline directed ortholithiation: synthesis and probe of chiral space

• Simon A. Herbert,
• Laura J. van Laeren,
• Dominic C. Castell and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2017, 13, 347–347, doi:10.3762/bjoc.13.38

• Simon A. Herbert Laura J. van Laeren Dominic C. Castell Gareth E. Arnott Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa 10.3762/bjoc.13.38 Keywords: calix[4]arene; inherently chiral; ortholithiation; oxazoline; Tsuji–Trost; In

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

• Basic Science, University of Mazandaran, Babolsar, Iran 10.3762/bjoc.12.163 Abstract Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited

• of 9.6 × 10−8 M. Keywords: calix[4]arene; chemosensor; copper ions; fluorene; fluorescence; Introduction Owing to the substantial role of fluorescent chemosensors in biological, environmental, and chemical processes, their design and synthesis, especially for detection of metal ions has attracted

• supramolecular structures, especially calixarene derivatives, has been an appealing field for research [14]. Calixarene has been considered as an effective molecular scaffold in the improvement of fluorescent and chromogenic sensors, especially for metal-ion recognition [14][15]. Calix[4]arene derivatives having

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• project: constructing calix[4]arene-derived catenanes, such as 7a–c [15] (Scheme 3). I chose this project because I believed that I could make progress in a short time. Most of the work was done by myself, but I also received assistance from several young technicians. We succeeded in investigating the

• effect of the calix[4]arene moiety on the relative rotation of the two rings using 1H NMR, and from 1998 to 2000, we published four papers from this project. However, this was generally a tough period for me. Due to some nonacademic reasons, I could not build an efficient research group after several

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• key building block for the synthesis of calix[4]arene. Here, α,ω-bis(p-methoxyphenyl)alkanes 264 were used as starting materials. Compound 264 was treated with acetic anhydride and AlCl3 in nitrobenzene and 1,1,2,2-tetrachloroethane to generate diketone 265 in 58–93% yield. Diketone 265 was then

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• . Although being reported in the literature, it has so far not found wide spread use and was employed only with a narrow scope of aromatic derivatives with electron-donating substituents and alkylthio-substituted (R = SAlkyl) MPTTFS. Being interested in the preparation of calix[4]arene receptors with MPTTF

• reaction with bromophenol 8d to form the adduct 4f also confirmed the possibility of the reaction with hydroxy-substituted aryl derivatives, paving the way for application of this method with non-protected calix[4]arene derivatives [27]. Compounds 4a–c,e,f (Figure 3) display UV–vis spectra typical for TTF

Inherently chiral calix[4]arenes via oxazoline directed ortholithiation: synthesis and probe of chiral space

• Simon A. Herbert,
• Laura J. van Laeren,
• Dominic C. Castell and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2014, 10, 2751–2755, doi:10.3762/bjoc.10.291

• examined as ligands in the palladium-catalyzed Tsuji–Trost allylation reaction, returning results comparable to their planar chiral ferrocene counterparts pointing towards future application of these types of compounds. Keywords: calix[4]arene; inherently chiral; ortholithiation; oxazoline; Tsuji–Trost

• other efforts relying on various resolution techniques [16][19][20][21][22][23][24][25][26]. We, however, have reported that stereocontrolled meta-functionalization of a calix[4]arene is possible via chiral oxazoline-directed ortholithiation [27][28]. This has allowed for a range of functionalized

• speculated that the additional steric bulk surrounding the coordination centre is responsible for the instability of the complex, thus promoting the formation of palladium black. When comparing the enantiomeric ratios, the results show that all four inherently chiral calix[4]arene ligands promote the

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