Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• the UCST behavior of such charged polymers, which can be manipulated via the hydrophobicity, polarizability, size, and especially the valency of the counterion [50][51]. While Flory et al. investigated the UCST behavior of PAA in the presence of large amounts of NaCl (c = 1.245 mol/L) already in 1954

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• intervalence charge transfer characteristics of the zwitterionic MV state. Keywords: anion binding; electrochemistry; hydrogen bonding; triarylamine; urea; zwitterionic mixed valency; Introduction Mixed-valence (MV) compounds have received increasing attention from the viewpoint of fundamental research on

• characteristics of the bis(NAr3)•+ radical cations are well documented due to their good availability through common N–C bond-forming reactions and the stability of the NAr3•+ unit [6][7][8][9][10][11][12][13][14][15][16][17][18]. Photoswitchable mixed valency has recently been demonstrated with bis(NAr3

• (Figure 1) [44]. The electrochemically control of H-bonding would have a dramatic impact on the field of mixed valency, which is striving to utilize charge delocalization for molecular devices. However, there is a lack of basic knowledge about the influence of an excess of supporting electrolytes on the

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

• Matthew B. Calvert,
• Varsha R. Jumde and
• Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

• compound was tested in a whole cell ELISA, it was shown that the apparent binding affinity increases by a factor of 250 versus methyl α-D-mannoside, while the valency only increased by a factor three. It should be noted that the full length FimH adhesin consists of two domains, a lectin and a pilin domain

Carbohydrate inhibitors of cholera toxin

• Vajinder Kumar and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34

• evaluated a pentavalent inhibitor 33 (Figure 14), analogous to their tetravalent compound 22b to investigate the difference between matching or mismatching the valency with that of the target CTB protein [56]. Previous biophysical studies had suggested that a mismatch in the valencies of ligand and receptor

• favoured an aggregation mechanism for inhibition [55] whereas matching the valency has previously been assumed to lead to the formation of 1:1 complexes [59][60][61][62][63][64]. They found that the potency exhibited by compound 33 in the usual enzyme-linked lectin assay (IC50 = 260 ± 20 pM) was slightly

• than five ligands While pentavalent inhibitors are seductive as they match the symmetry with the CTB protein, many researchers have sought to exceed the valency of five. In many cases this is largely for convenience of preparation of polymers bearing multiple pendant groups, or to achieve inhibitors

What contributes to an effective mannose recognition domain?

• Christoph P. Sager,
• Deniz Eriş,
• Martin Smieško,
• Rachel Hevey and
• Beat Ernst

Beilstein J. Org. Chem. 2017, 13, 2584–2595, doi:10.3762/bjoc.13.255

• in the context of a novel therapeutic approach against viral and bacterial infections [79]. However, carbohydrate valency, spacing, and branching all need to be thoughtfully considered with this class of therapeutics [15][80]. Conclusion Mannose-recognizing lectins fulfill a myriad of purposes and

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• database provided description of the main features of this important class of proteins. Lectins exhibit a variable oligomeric assembly that ranges from mono- to deca-valency (Figure 11). Lectins present sugar-binding sites that are in most cases relatively shallow, and are located near the surface and

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• ]. It was found that irradiation times of 14 min could be employed to afford CDs from glycerol, glycol, glucose or sucrose. The source of the inorganic ion was important too, as increasing the valency of either the anion or cation would lead to a greater ability to dehydrate the carbon precursor. An

Exploring architectures displaying multimeric presentations of a trihydroxypiperidine iminosugar

• Camilla Matassini,
• Stefania Mirabella,
• Andrea Goti,
• Inmaculada Robina,
• Antonio J. Moreno-Vargas and
• Francesca Cardona

Beilstein J. Org. Chem. 2015, 11, 2631–2640, doi:10.3762/bjoc.11.282

• synthesis of two different scaffolds bearing terminal alkyne moieties suitable for conjugation to compound 4. A preliminary evaluation of the role of the valency in enhancing the inhibitory activity of the iminosugar was investigated by synthesizing a tetravalent and a nonavalent scaffold. The tetravalent

• multivalent effect cannot be claimed, since the enhancement observed is not higher than 9-fold (the valency of the dendrimeric compound). Since in our experience the inhibition data towards commercial and human glycosidases do not always match [28], we then decided to evaluate the most promising nonavalent

Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

• Stefanie Krysiak,
• Qiang Wei,
• Klaus Rischka,
• Andreas Hartwig,
• Rainer Haag and
• Thorsten Hugel

Beilstein J. Org. Chem. 2015, 11, 828–836, doi:10.3762/bjoc.11.92

• microscopy (AFM). The comparison of single catechols (dopamine) with multiple catechols on hyperbranched polyglycerols (hPG) at various pH and dwell times allowed us to further increase our understanding. In particular, we were able to elucidate how to achieve strong bonds of different valency. It was

• concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings. Keywords: adhesion; atomic force microscopy; catechol; hyperbranched polyglycerols; valency; Introduction While underwater glues are still a challenge for industrial adhesive

• possible and allows for good cohesion between the layers of this material. Here we investigated the molecular details, valency and dynamics on how molecules with multiple DOPA groups adhere to surfaces. Results and Discussion The publication by Lee et al. [11] sparked considerable interest and since then

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• model systems with known valency are valuable tools to be studied by single-molecule force spectroscopy (SMFS). In SMFS experiments a modified probe – an optical tweezers bead or an SFM cantilever – is used to measure interaction forces with modified synthetic or biological surfaces. The distribution of

Influence of length and flexibility of spacers on the binding affinity of divalent ligands

• Susanne Liese and
• Roland R. Netz

Beilstein J. Org. Chem. 2015, 11, 804–816, doi:10.3762/bjoc.11.90

• overwhelming variety of multivalent ligand architectures that range from small divalent ligands to densely packed nanoparticles, led to different approaches to describe multivalency, depending on the size and valency of the system. Several studies aimed to treat ligand–receptor systems with different

• multivalent dissociation constant, in the limit of low receptor concentrations, i.e., for [R]0 << Kmulti: To compare monovalent and multivalent ligands we use the relative binding affinity (RBA), which we define as Here, the factor 2 accounts for the valency of the ligand and ensures that the concentration of

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• depending on the valency of the catecholate. Bromotriscatecholate 13 was chosen as a hydrophobic analogue to 3. ZnO particles were synthesized according to a literature known procedure from Zn(acac)2 [30]. Powders separated by the centrifugation of the precursor suspensions were investigated by X-ray

Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency

• Anna K. Ciuk and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 668–674, doi:10.3762/bjoc.11.75

• dimerized by [2 + 2] photocycloaddition. Thus, thymine functions as a control element that allows to restrict the conformational flexibility of the scaffolded sugar ligands and thus to “organize” multivalency. With this work we add a parameter to multivalency studies additional to valency. Keywords: [2 + 2

• influence their recognition by lectins [7]. Recently, we have introduced a photoswitchable glycoazobenzene-covered surface, in which alteration of ligand orientation allowed to switch cell adhesion without changing the recognition quality or the valency of the ligand itself [6]. It is also well-known that

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• fluorophore core is naturally primordial for the design of photostable, water-soluble and biocompatible probes with the required photophysical properties. An additional challenge is that, as the central core of a multivalent system, the fluorophore structure defines also its valency, size and shape

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

• Meriem Smadhi,
• Sophie de Bentzmann,
• Anne Imberty,
• Marc Gingras,
• Raoudha Abderrahim and
• Peter G. Goekjian

Beilstein J. Org. Chem. 2014, 10, 1981–1990, doi:10.3762/bjoc.10.206

• , France Centre de Recherches sur les Macromolécules Végétales (CERMAV), UPR 5301 CNRS et Université Grenoble Alpes, BP53, 38041 Grenoble, France Aix-Marseille Université, CNRS, CINaM UMR 7325, 163 Avenue de Luminy 13288 Marseille, France 10.3762/bjoc.10.206 Abstract Readily accessible, low-valency

• convenient access to low valency mono- or heterobifunctional glycoclusters. As expected, they display excellent aqueous solubility due of the combination of a dendritic polyheterocyclic architecture and carbohydrate epitopes. Biophysical studies Dynamic light scattering experiments (DLS) were performed on

• clusters is due to potential effects on P. aeruginosa lectins. Conclusion We have developed a convenient synthesis of simple, low-valency glycoclusters. These compounds have good solubility, are readily accessible, and are easy to purify and to characterize. The presence of the sulfur provides beneficial

Synthesis of the first examples of iminosugar clusters based on cyclopeptoid cores

• Mathieu L. Lepage,
• Alessandra Meli,
• Anne Bodlenner,
• Céline Tarnus,
• Francesco De Riccardis,
• Irene Izzo and
• Philippe Compain

Beilstein J. Org. Chem. 2014, 10, 1406–1412, doi:10.3762/bjoc.10.144

• with different valency and alkyl spacer lengths by means of Cu(I)-catalysed azide–alkyne cycloadditions. Evaluation of these compounds as α-mannosidase inhibitors led to significant multivalent effects and further demonstrated the decisive influence of scaffold rigidity on binding affinity enhancements

• ], β-cyclodextrin [4][5] and porphyrin [7] cores, and with nanoparticles prepared by self-assembly of iminosugar-based glycopolypetides [6]. So far, the largest multivalent effect (up to 610-fold relative inhibition potency increase on a valency-corrected basis) has been achieved on jack bean α

• scaffold is crucial as it defines the valency, the size and the shape of the multivalent architectures. Due to their broad chemical diversity, rapid and convenient synthetic access, improved proteolytic stability and cell permeability over peptides, N-substituted glycine oligomers, called peptoids [14][15

Human dendritic cell activation induced by a permannosylated dendron containing an antigenic GM₃-lactone mimetic

• Renato Ribeiro-Viana,
• Elena Bonechi,
• Javier Rojo,
• Clara Ballerini,
• Giuseppina Comito,
• Barbara Richichi and
• Cristina Nativi

Beilstein J. Org. Chem. 2014, 10, 1317–1324, doi:10.3762/bjoc.10.133

• dendron has the adequate size and valency to efficiently interact with this receptor. Dendron 7 (Scheme 1), presenting an azido group at the focal position, was synthesized as previously described [35]. This functionalization permits, in a further step, the conjugation of any molecule conveniently

Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines

• Kebin Mao,
• Guoqin Fan,
• Yuanhong Liu,
• Shi Li,
• Xu You and
• Dan Liu

Beilstein J. Org. Chem. 2013, 9, 621–627, doi:10.3762/bjoc.9.69

• Chemical Technology, Shenyang 110142, People’s Republic of China 10.3762/bjoc.9.69 Abstract Low-valency titanium species, generated in situ by using Ti(OiPr)4/2 c-C5H9MgCl reagent, react with imines to give a titanium-imine complex that can couple with terminal alkynes to provide azatitanacyclopentenes

• ], etc., it is still a great challenge to synthesize allylic amines with a stereodefined alkene moiety. The low-valency group 4 metal complexes (M = Ti or Zr) mediated reductive cross-coupling of imines with alkynes is one of the useful methods to construct stereodefined allylic amines. For example

• limitations for titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes have been far less studied. Our group has developed a series of reactions using low-valency titanium reagents [37][38][39], including selective coupling of 1,3-butadiynes with aldehydes using Ti(OiPr)4/2 n

Efficient synthesis of phenylene-ethynylene rods and their use as rigid spacers in divalent inhibitors

• Francesca Pertici,
• Norbert Varga,
• Arnoud van Duijn,
• Matias Rey-Carrizo,
• Anna Bernardi and
• Roland J. Pieters

Beilstein J. Org. Chem. 2013, 9, 215–222, doi:10.3762/bjoc.9.25

• favorably with the monovalent reference compound 25 (Figure 5), which exhibited an IC50 of 120 μM [10]. Similarly, the divalent compound 22 was a more potent inhibitor than the higher valency compound 26, especially when expressed as the relative potency per sugar, which is 11 for the tetravalent 26 [37][38

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

• units. With the purpose of expanding the valency and increasing the glycoside density, glycodendrimers have also been synthesised and their properties in protein–carbohydrate interactions have been studied [24][25][26]. However, the innovative frontier of combining glycodendrimeric arrangements onto a

• -generation iminosugar-type calixarene-based dendrimers, demonstrating the feasibility of increasing the valency of the cluster by combining a dendrimeric arrangement of iminosugar ligands with a multivalent calixarene core. Results and Discussion We chose to address the conjugation of iminosugar-analogue

• 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

Synthetic glycopeptides and glycoproteins with applications in biological research

• Ulrika Westerlind

Beilstein J. Org. Chem. 2012, 8, 804–818, doi:10.3762/bjoc.8.90

• - and trivalent glycopeptides were evaluated for their inhibition of FimH binding [107]. The valency, conformational properties, and spatial arrangement of the attached mannose residues were evaluated. Glycopeptides containing an aromatic aglycon showed increased affinity to FimH due to interactions

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

• microtiter plates (data not shown). These products offer also the possibility of direct comparison between binding to soluble and immobilised poly-LacNAc glycans. This is especially important as it was shown that the presentation mode and the valency of glycans have a high impact on protein-binding