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

• increasingly important applications [11]. A specific category of modified CDs are the CD oligomers, compounds with two or three CD macrocycles linked together at different positions (2–2’, 3–3’, 3–2’, 6–2’ etc) via selected spacers. The multicavity structures can, in principle, be precisely tailored to fit

• specific guest molecules. The oligomers are reported to display improved to significantly enhanced binding capacity as well as superior molecular recognition ability [12][13][14], compared to the natural CDs. Suitable design has resulted in better hosts for applications as sensors and catalysts [15], hosts

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• analyzed by MALDI–TOF mass spectrometry indicating the formation of oligomers with m/z = 422 to 1046. We could efficiently suppress this oligo- and polymerization by increasing the amount of solvent, i.e. by dilution (Table 1, entries 9–13). Additionally increasing the concentration of KOH and water also

Synthesis of novel derivatives of 5-hydroxymethylcytosine and 5-formylcytosine as tools for epigenetics

• Anna Chentsova,
• Era Kapourani and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 7–11, doi:10.3762/bjoc.10.2

• of the TCBoc group afforded derivatives 9a–d. These new nucleobase modified 2’-deoxycytidine analogues can be used in the synthesis [29][33][34] of modified DNA oligomers for further studies of the TET-mediated processes which are of great importance in the emerging field of epigenetics. In addition

Studies toward bivalent κ opioids derived from salvinorin A: heteromethylation of the furan ring reduces affinity

• Thomas A. Munro,
• Wei Xu,
• Douglas M. Ho,
• Lee-Yuan Liu-Chen and
• Bruce M. Cohen

Beilstein J. Org. Chem. 2013, 9, 2916–2924, doi:10.3762/bjoc.9.328

• ligands with a furanylmethyl substituent (Figure 3), we decided to use a short linker. As an alternative approach, bivalent ligands with much longer linkers can bind simultaneously to both protomers in a receptor dimer, allowing selective targeting of specific receptor oligomers [21]. We also sought to

Triphenylene discotic liquid crystal trimers synthesized by Co₂(CO)₈-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition

• Bin Han,
• Ping Hu,
• Bi-Qin Wang,
• Carl Redshaw and
• Ke-Qing Zhao

Beilstein J. Org. Chem. 2013, 9, 2852–2861, doi:10.3762/bjoc.9.321

• ][17], and organic photovoltaic solar cells (OPVs) [18][19][20]. The reported DLC oligomers [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] are limited compared with the low-molar-mass DLCs and polymeric DLC materials, due to the

• construction methods for the oligomers. However, DLC oligomers usually possess wider mesophase ranges than the monomers as the crystallization was prevented, due to the size of molecules is enlarged and molecular symmetry is lowered. However DLC oligomers exhibit higher charged carrier mobility than DLC

• polymers, the most important parameter in determining the device performance, as the discotic unites can still self-assemble to higher order through the π–π interaction. In addition, DLC oligomers similar to polymers can be processed on flexible substrates by spin-casting, screen printing, doctor-blading

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

• used [3][4]. However, non-bisphenol A based diepoxides are subject to intensive research [5][6][7][8][9]. The industrial synthesis of BADGE and other commercially available diepoxides proceeds mainly by using epichlorohydrin, whereby usually several side products and oligomers are formed in significant

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

• diglycidyl ether to give novel oligomeric thermoresponsive epoxide–amine adducts. These oligomers exhibit a lower critical solution temperature (LCST) behavior in water. The solubility properties were influenced with randomly methylated β-cyclodextrin (RAMEB-CD) and the curing properties of the amine–epoxide

• mixtures were analyzed by oscillatory rheology and differential scanning calorimetry, whereby significant differences in setting time, viscosity, and stiffness were observed. Keywords: amino acids; curing properties; cyclodextrin; epoxide–amine oligomers; LCST; Introduction Many partially hydrophobic

• present paper we wish to describe our results about preparation and solubility of novel bio-based amine–epoxy oligoadducts. Also, we present some effects of CD on the solubility of these oligomers. Results and Discussion Generally, primary amins are bifunctional towards diepoxides and are thus monomers

Synthesis of homo- and heteromultivalent carbohydrate-functionalized oligo(amidoamines) using novel glyco-building blocks

• Felix Wojcik,
• Sinaida Lel,
• Alexander G. O’Brien,
• Peter H. Seeberger and
• Laura Hartmann

Beilstein J. Org. Chem. 2013, 9, 2395–2403, doi:10.3762/bjoc.9.276

• the straightforward synthesis of multivalent glycoligands with full control over monomer sequence and functionalization pattern. We demonstrate the potential of this building-block approach by synthesizing oligomers with different numbers and spacing of carbohydrates and also show the feasibility of

• [20]. Carbohydrate conjugation was achieved by copper-catalyzed azide alkyne cycloaddtion (CuAAC) of carbohydrate ligands on alkyne presenting oligomers [21]. As an alternative conjugation approach to CuAAc, a very efficient thiol–ene coupling (TEC) [22][23][24][25] protocol in a continuous flow

• photoreactor was developed involving post functionalization of alkene presenting oligomers by thioglycosides [26]. The flow system allows for precise control over the reaction conditions, is easy to scale up and provides efficient irradiation of the samples by virtue of a sub-millimeter path length. Continuous

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• and core 3 disaccharide precursors 14 and 15 were then prepared in the presence of catalytic TMSOTf in respective yields of 90% and 76%. Global deprotection of the assembled oligomers was achieved by a tandem process that required no purifications between steps, as the reactions proceeded cleanly as

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• in solution, both 16-electron and 14-electron species are obtained, though the latter are not stable, and only oligomers with bridging hydrides can be detected [125]. Wang and co-workers disclosed the spontaneous self-assembling of [Pt(Me)2(NPA)] 45 by a “rollover” cyclometalation process (Scheme 21

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

• significantly shifts from 343 nm to 615 and 5489 nm. The hydrodynamic diameter of 615 nm can be explained by the formation of some macrocycles and oligomers by noncovalent interactions of the host and guest molecules. This phenomenon might also explain the almost unchanged viscosity increase of the complex in

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• containing perfluorohexylthiophene units at the terminal positions on the arms were synthesised, and their optical and electrochemical properties were investigated to determine the effect that the perfluorohexylthiophene unit has on the HOMO and LUMO properties of the oligomers. By synthesising a molecule

• with longer oligofluorene arms the effects of the perfluorohexylthiophene unit on larger oligomers was explored. The effect of steric hindrance from the perfluorohexyl chain was also evaluated by altering the position of the chain on the thiophene moiety. Keywords: oligomers; perfluorinated-materials

• ; star-shaped molecules; synthesis; truxene; Introduction Star-shaped oligomers share a common central unit with multiple arms branching from the core [1]. The morphology and electronic properties of these oligomers often vary from the linear versions of the arms alone. 10,15-Dihydro-5H-diindeno[1,2-a;1

Efficient regio- and stereoselective access to novel fluorinated β-aminocyclohexanecarboxylates

• Loránd Kiss,
• Melinda Nonn,
• Reijo Sillanpää,
• Santos Fustero and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1164–1169, doi:10.3762/bjoc.9.130

• appreciable in the case of peptide oligomers formed from conformationally restricted fluorinated amino acids. Although cyclic β-amino acids are of major interest in pharmaceutical chemistry and in peptide research [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

• Amaresh Mishra,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

• oligomers and polymers are amongst the best-studied π-conjugated systems in the past few decades because of their tunable optoelectronic properties [6][7][8]. Furthermore, transition-metal complexes offer significant advantages such as long-lived luminescent excited states, high chemical and photochemical

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

• of 50–70% were obtained for the ROP of rac-lactide, which afforded oligomers. The incomplete conversion can be explained by the viscous nature of the reaction mixture, resulting in PLA formation and limiting the polymerization process. Besides, increasing the amount of alcohol and consequently the

• zwitterionic intermediate (propagation step, Scheme 2). As a consequence, if the ratio of monomer to alcohol initiator is too low, the latter can compete with the formed hydroxy-terminated monomers/polymers to initiate the formation of a new polymer chain, and the propagation is stopped. In this case oligomers

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• methods. The main limitation is that the initial radical R· has to be more stable than adduct radical 29 in order to bias the equilibrium in favour of product 30 and avoid the formation of oligomers by further additions of radical 29 to the alkene. Radicals R· stabilised by electron-withdrawing groups

Peptoids and polyamines going sweet: Modular synthesis of glycosylated peptoids and polyamines using click chemistry

• Daniel Fürniss,
• Timo Mack,
• Frank Hahn,
• Sidonie B. L. Vollrath,
• Katarzyna Koroniak,
• Ute Schepers and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 56–63, doi:10.3762/bjoc.9.7

• oligonucleotides [5][6][7][11][12][13] displaying only very little toxicity towards mammalian cells [11]. They have also been shown to function in the recognition of biomacromolecules. Likewise, other polycationic species, such as the N-alkylated glycine oligomers (peptoids) [14][15][16][17][18][19][20][21][22][23

• conjugation (Scheme 2) with minor modifications. The CuAAC was carried out by using Cu(CH3CN)4PF6 in THF with 2,6-lutidine as base. Only 1.60 equiv of the azidosugar were necessary to achieve full conversion after 18 h, and no shorter oligomers were observed in the MALDI–TOF spectrum. Cleavage from the resin

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

New efficient ligand for sub-mol % copper-catalyzed C–N cross-coupling reactions running under air

• Per-Fredrik Larsson,
• Peter Astvik and
• Per-Ola Norrby

Beilstein J. Org. Chem. 2012, 8, 1909–1915, doi:10.3762/bjoc.8.221

• higher concentrations [77]. A value lower than 1 indicates that an active monomeric catalyst is in equilibrium with inactive dimers or higher oligomers. The reaction order never drops to zero, as it did with DMEDA, showing that the formation of insoluble aggregates at high concentration [87] is avoided

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

• ; cyclodextrins; graft copolymer; macromonomer; ring-opening free radical polymerization; 2-vinylcyclopropane; Introduction Macromonomers are polymers or oligomers with at least one functional end group that is capable of further polymerization. The molecular weight of macromonomers generally ranges between 1000

• studied area [7][8]. β-Cyclodextrins (β-CDs) are cyclic oligomers consisting of seven α-1,4-glycosidically linked glucopyranose units which are present in the chair conformation [9][10][11][12]. The molecule resembles a truncated cone with approximate Cn-symmetry [13]. The cyclic 1,4-linked glucose units

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence

• Akihito Hashidzume,
• Yongtai Zheng and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1312–1317, doi:10.3762/bjoc.8.150

• fluorescence; water/DMSO mixed solvent; Introduction Cyclodextrins (CDs) are cyclic oligomers composed of glucopyranose units linked through α-1,4-glycoside bonding. They bear a tapered structure with a narrower rim of primary hydroxy groups and a wider rim of secondary hydroxy groups. CDs of 6, 7, and 8

Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41

• Evan F. Haney,
• Leonard T. Nguyen,
• David J. Schibli and
• Hans J. Vogel

Beilstein J. Org. Chem. 2012, 8, 1172–1184, doi:10.3762/bjoc.8.130

• attempts to resolve the NMR structure of gp41w in aqueous solution or 40% TFE were unsuccessful because of peptide aggregation or poor solubility [12]. In terms of the antimicrobial activity, gp41w oligomers may be too large to pass through the peptidoglycan layer surrounding Gram-positive bacteria

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

• Raphael Reuter and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2012, 8, 877–883, doi:10.3762/bjoc.8.99

• , however, only one azobenzene unit is incorporated. One of the reasons is the synthetic challenge associated with the preparation of such oligomers. Solubility and, especially, selectivity issues have to be addressed. Another reason is the higher complexity of the photochemistry of these multi-photochromic

• biphenyl restores the photoisomerization properties (Figure 1) [18][19]. In a related example by Samanta and Woolley a similar compound was presented featuring anchoring groups for biological applications (Figure 1) [20]. In another study the team of Hecht synthesized oligomers separated by alkynyl linkers

• independent if two azo units are connected via a biphenyl unit in meta-positions, there seem to be subtle differences that influence the preference as to which azo bond is switched preferentially. Such a property will be highly useful in the design of selective, switchable, functional oligomers. Conclusion In

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• modification of terminal galactose and N-acetylgalactosamine residues of poly-N-acetyllactosamine (poly-LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) by galactose oxidase. Product formation starting from different poly-LacNAc oligomers was characterised and optimised regarding formation of the C6

• oligomers containing terminally and/or internally modified galactose residues were obtained, which can be used for binding studies and various other applications. Keywords: chemo-enzymatic synthesis; galactose oxidase; glycosyltransferase; LacDiNAc; poly-N-acetyllactosamine; Introduction N

• conversion of the 6-aldehyde group to the corresponding α,β-unsaturated aldehyde by base-catalysed β-elimination (Scheme 1). The galactose 6-aldehydes of poly-LacNAc oligomers were chemically converted to their corresponding α,β-unsaturated aldehydes under elevated temperature at alkaline pH in almost

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• Stefanie Potratz Amaresh Mishra Peter Bauerle University of Ulm, Institute of Organic Chemistry II and Advanced Materials, Albert-Einstein-Allee 11, 89081 Ulm, Germany 10.3762/bjoc.8.76 Abstract Herein we present a three-component one-pot procedure to synthesize co-oligomers of a donor–acceptor

• -triazole co-oligomers were investigated by UV–vis spectroscopy and cyclic voltammetry. Several co-oligomers were electropolymerized to the corresponding conjugated polymers. Keywords: acetylene; azide; click chemistry; thiophene; triazole; Introduction Oligo- and polythiophenes are among the most

• extensively investigated organic semiconducting materials used in organic electronics [1][2][3]. In this respect, various oligomers have been developed by using metal-catalyzed Suzuki-, Stille-, Sonogashira-, and Kumada-type cross-coupling reactions [4][5][6][7][8][9]. On the other hand, the so-called “click