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

• 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

• superstructures, CDs and calixarenes turned out to be very attractive not only as molecular receptors but also as building blocks for the construction of supramolecular architectures [5]. For that reason, we were encouraged to couple these two different types of macrocycles via click type reactions. Recent

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

• solvent-ligand bonds to break – as well as entropic – macrocycles [33] or cavities [34] being less conformationally flexible so losing fewer degrees of freedom upon complexation as a result of the reorganization energy already paid in advance in the synthesis. In a few examples, guest molecules are

• ]. Important heterocrowns (Figure 6) are macrocycles such as cyclens (6) and cyclams (7), which show excellent complexation properties towards transition metal ions [110]. Special classes of crown ethers are pyridino crowns (9), with one or more oxygen atoms replaced by pyridino moieties in the polyether chain

• )propane and the corresponding heteroaromatic macrocycles containing pyridine units [129] (Figure 9). The cyclic receptor 13 is a most effective carrier of ammonium ions (ν = 57 μM h−1) and exhibits an excellent selectivity for NH4+ in relation to three metal cations investigated (NH4+/Na+ = 9.2, NH4+/K

(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

• acid. Following the same objective, Xie’s group prepared orthogonally protected cyclic homo-oligomers with two to four SAA units that can be selectively or fully deprotected to afford macrocycles that can undergo further functionalisation (Figure 11) [55]. Conformational analysis by molecular modelling

Templated versus non-templated synthesis of benzo-21-crown-7 and the influence of substituents on its complexing properties

• Wei Jiang and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2010, 6, No. 14, doi:10.3762/bjoc.6.14

• complexes with several C7 crown ethers, this peak distribution can only be assigned to a series of macrocycles with different sizes ranging from dibenzo-42-crown-14 (2-(1)) up to heptabenzo-168-crown-56 (2-(7)). Although the peak intensity does not necessarily reflect the solution composition quantitatively

Synthesis and binding studies of two new macrocyclic receptors for the stereoselective recognition of dipeptides

• Ana Maria Castilla,
• M. Morgan Conn and
• Pablo Ballester

Beilstein J. Org. Chem. 2010, 6, No. 5, doi:10.3762/bjoc.6.5

• explained below. The exploration of the conformational space of both macrocycles, using molecular modeling, indicated the existence of a built-in cavity. These studies also suggested that the reduced conformational flexibility of the receptors avoids the complete collapse of the cavity through the formation

• skeleton of the receptor. The two designed macrocycles, 1 and 2, have been synthesized and fully characterized. One of the key synthetic steps, which is common to both synthetic routes, consists in the use of a Stille carbonylative cross-coupling reaction that affords orthogonally tetraprotected 4,4’-bis

An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III) ions

• Markus Albrecht,
• Olga Osetska,
• Thomas Abel,
• Gebhard Haberhauer and
• Eva Ziegler

Beilstein J. Org. Chem. 2009, 5, No. 78, doi:10.3762/bjoc.5.78

• should be prototypes for further lanthanide(III) complexes with an enterobactine analogue binding situation. Keywords: CD spectroscopy; enterobactin; lanthanide; macrocycles; molecular modeling; Introduction The availability of metal ions for biological systems is essential for growth and function

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• Andreas Speicher Timo Backes Kerstin Hesidens Jurgen Kolz Department 8.1 Chemistry – Organic Chemistry, Saarland University, 66041 Saarbrücken, Germany 10.3762/bjoc.5.71 Abstract Macrocycles of the bisbibenzyl-type are natural products that are found exclusively in bryophytes (liverworts). The

• macrocycles. Keywords: axially chiral biaryl; isoplagiochin; macrocycle; ring strain; total synthesis; Introduction The cyclic bisbibenzyls isoplagiochin C (1) and D (2) were isolated from the liverworts Plagiochila fruticosa [1], Plagiochila deflexa [2], Herbertus sakuraii [3] and Lepidozia fauriana [4

• separated. By 2D NMR experiments (COSY, HSQC, HMBC) at 100 °C four sharp signals could be assigned to the methoxy groups in rings a–d (Figure 3). To gain insight into possible ring strain limitations for the preparation and stability of modified macrocycles of the isoplagiochin type we performed molecular

Synthesis of dihydrophenanthridines by a sequence of Ugi-4CR and palladium- catalyzed intramolecular C-H functionalization

• Florence Bonnaterre,
• Michèle Bois-Choussy and
• Jieping Zhu

Beilstein J. Org. Chem. 2008, 4, No. 10, doi:10.3762/bjoc.4.10

• developed two-step syntheses of a number of macrocycles including cyclophanes and cyclodepsipeptides [7][8][9][10]. We have also reported the elaboration of Ugi-adduct containing two arylhalide functions for the synthesis of 1,4-benzodiazepine-2,5-diones [11] and their tetracyclic derivatives [12] featuring

Shape- persistent macrocycle with intraannular alkyl groups: some structural limits of discotic liquid crystals with an inverted structure

• Sigurd Höger,
• Jill Weber,
• Andreas Leppert and
• Volker Enkelmann

Beilstein J. Org. Chem. 2008, 4, No. 1, doi:10.1186/1860-5397-4-1

• -Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany 10.1186/1860-5397-4-1 Abstract The synthesis and thermal properties of new shape-persistent macrocycles of different sizes decorated with intraannular alkyl chains are described. The alkyl chain length is in all cases sufficient

• than spheres. For the larger macrocycles it is shown that longer adaptable substituents decrease the phase transition temperatures compared to previously described structures. Background During the past several years, the interest in the design and study of shape-persistent macrocycles with an

• , the supramolecular chemistry of rigid rings is currently investigated with considerable effort. For example, shape-persistent macrocycles can act as host structures for appropriate guest molecules; they can form 1D aggregates (in solution or gas phase) or regular 2D lattices after deposition at

Molecular recognition. 1. Crystal structures of hexaazamacrocyclic amines containing p-xylylene spacers and their adducts with acids

• Teresa Borowiak,
• Grzegorz Dutkiewicz,
• Maciej Kubicki,
• Marek Pietraszkiewicz,
• Agnieszka Gil and
• Rainer Mattes

Beilstein J. Org. Chem. 2005, 1, No. 16, doi:10.1186/1860-5397-1-16

• +-H groups which come from two different macrocycles. Hereby the zigzag arrangement mentioned above is formed. A second bifurcated hydrogen bonding is formed to two different water molecules which fill up the empty space between two neighbouring tapes (Figure 2). Further, each of two C-O- bonds of the