Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• built on by Zhang et al. along with another low molecular weight, CO2-philic polymer; poly(vinyl ethyl ether), (PVEE, Figure 5, compound 38) [98][99]. Viscosities of the polymer-thickened CO2 were measured by capillary viscometry across a range of pressures along with cloud point pressures. Higher

• phenomena [32][41]. The addition of low molecular weight polymers has shown some promise, with viscosity increases being observed in polymer containing CO2 in comparison to pure CO2, which are attributed to strong intermolecular forces arising from π–π interactions of phenyl groups in the polymeric

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts

• Jong Yeob Jeon,
• Seong Chan Eo,
• Jobi Kodiyan Varghese and
• Bun Yeoul Lee

Beilstein J. Org. Chem. 2014, 10, 1787–1795, doi:10.3762/bjoc.10.187

• production of poly(propylene carbonate) (PPC) using catalyst 1 is at the stage of the final decision regarding a commercial investment. Another success story using double metal cyanide (DMC) catalysts has been reported recently [20]. The DMC catalysts provided low-molecular-weight CO2/PO copolymers

• -weight mode was always twice that in the low-molecular-weight mode. The chains in the high-molecular-weight mode were attributed to those grown biaxially from water, which was present as an impurity, while those in the low-molecular-weight mode were grown from the nitrate and acetate anions in 1. The

• water molecules per 1 present as an impurity (8, 10, 8, and 4, respectively). The portion of the high-molecular-weight mode (that is, the portion of chains grown from water molecules) relative to the portion of the low-molecular-weight mode decreased in the GPC curves in the order of entries 2, 3, and 4

A promising cellulose-based polyzwitterion with pH-sensitive charges

• Thomas Elschner and
• Thomas Heinze

Beilstein J. Org. Chem. 2014, 10, 1549–1556, doi:10.3762/bjoc.10.159

• -soluble polyelectrolytes, containing anionic or cationic groups, and polyzwitterions that include both charges. While the addition of low molecular weight electrolyte cause the polyelectrolyte effect, i.e., the shrinking and precipitation of the polyelectrolyte, polyzwitterions show chain expansion and

• -101) with a DPw of 330 was purchased from Sigma-Aldrich and dried at 60 °C in vaccum. Polydiallyldimethylammonium chloride (Sigma-Aldrich) with a very low molecular weight of Mw < 100000 g/mol was used as received. Other chemicals and solvents were purchased from Sigma-Aldrich, Acros Organics or TCI

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• polyethylene glycol (PEG), known as PEGylation, has been widely used to improve the bioavailability of proteins and low molecular weight drugs. The covalent conjugation of PEG to the carbohydrate moiety of a protein has been mainly used to enhance the pharmacokinetic properties of the attached protein while

• and viral infections and are consequently candidates for chemotherapy. The short in vivo half-life of low molecular weight glycans hampered their use but methods for the covalent attachment of PEG have been less exploited. In this review, information on the preparation and application of PEG

• adenovirus coat for vaccine development [5], antibodies or antibody fragments to prolong their circulating half-lives in vivo [6] and selective alkylation and acylation of amino groups in a somatostatin analog using two different PEG reagents [7]. Also, PEGylation of low molecular weight drugs in order to

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• plasmon resonance (SPR) spectroscopy a commercially available polycarboxylate hydrogel sensor surface was employed, which is known to be particularly advantageous for low molecular weight compounds due to the signal amplification caused by multiple binding events in the hydrogel on the sensor. The

• of the SPR signal is certainly due to the low molecular weight of HisHis which limits any further SPR investigations. Additionally, bifunctionalized carbohydrate surfaces were incubated simultaneously with FITC-HisHis, TRITC-ConA, and FITC-PNA to elucidate whether selective binding of the synthetic

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• globule transition at the lower critical solution temperature (LCST) of approximately 33 °C in water for low molecular weight polymers as stated in previous studies [41][42]. In the present study, the cloud points of PDEAAm were measured on 1 wt % aqueous solution in water. A concentration of 1 wt

• during the phase transition is initiated at the chain ends, where the mobility is highest [36]. For poly(N-isopropylacrylamide) (PNIPAM) previous studies demonstrated a broadened phase transition for polydisperse and low molecular weight samples [18][32][43]. Although the polymers (8a–d, 9a–d

• ) investigated in the present study were prepared via a free-radical instead of a living polymerization technique and had a relative low molecular weight, the optical transmission diagrams indicate a relatively sharp transition in a temperature range of 1 °C up to 2 °C as well as a good reversibility upon

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• 3-CR, the Ugi 4-CR is favoured in polar protic solvents like low-molecular weight alcohols such as methanol, ethanol or trifluoroethanol. However, many examples in polar aprotic solvents are also reported. The generally accepted mechanism for the Ugi reaction proceeds via in situ imine formation of

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• ; Introduction The creation of one-dimensional (1D) nanostructures is one of the focused fields in supramolecular chemistry [1][2][3][4]. In order to control the molecular arrangement in 1D structures, low molecular weight gelators (LMWGs) have generated considerable interest during the past decade [5][6]. The

• ]. Besides the mixed solvents, gelation and partial gelation also occurred in ethylene glycol (entry 12, Table 1) and acetonitrile (entry 13, Table 1). In aromatic solvents (entries 14 and 15, Table 1), chlorinated solvents (entries 16 and 17, Table 1) and low molecular weight alcohols (entries 18 and 19

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• with benzyloxyketene and simply remain undetected, but it is clear that the control of diastereofacial selectivity in the formation of the principal β-lactam is strongly under the control of the SF5 group. Conclusion Low molecular weight pentafluorosulfanylated aldehydes 1 were prepared by addition of

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• can be exploited for selective intracellular delivery and release of bioactive agents like DNA or low molecular-weight drugs [34]. Especially in the human blood stream the molecular weight is of significant importance for prolonged circulation cycles and enhanced selectivity for diffusion into tumor

Controlled synthesis of poly(3-hexylthiophene) in continuous flow

• Helga Seyler,
• Jegadesan Subbiah,
• David J. Jones,
• Andrew B. Holmes and
• Wallace W. H. Wong

Beilstein J. Org. Chem. 2013, 9, 1492–1500, doi:10.3762/bjoc.9.170

• 3 (see Table 1 for experimental data). MALDI mass spectrum of low-molecular-weight preparation (GPC, Mn = 6.2 kg/mol) of P3HT in continuous flow. Signals corresponding to polymer chains with o-tolyl/H, H/H and Br/H end groups were observed. Plot of number-average molecular weight, Mn, versus monomer

Synthesis and physicochemical characterization of novel phenotypic probes targeting the nuclear factor-kappa B signaling pathway

• Paul M. Hershberger,
• Satyamaheshwar Peddibhotla,
• E. Hampton Sessions,
• Daniela B. Divlianska,
• Ricardo G. Correa,
• Anthony B. Pinkerton,
• John C. Reed and
• Gregory P. Roth

Beilstein J. Org. Chem. 2013, 9, 900–907, doi:10.3762/bjoc.9.103

• efforts are ongoing to improve molecular potency and properties to make each chemical scaffold family suitable for advanced in vivo studies. Each probe represents a low-molecular-weight, “rule of 5” compliant starting point for target identification or lead optimization efforts. In screening the MLSMR

Synthesis and evaluation of cell-permeable biotinylated PU-H71 derivatives as tumor Hsp90 probes

• Tony Taldone,
• Anna Rodina,
• Erica M. DaGama Gomes,
• Matthew Riolo,
• Hardik J. Patel,
• Raul Alonso-Sabadell,
• Danuta Zatorska,
• Maulik R. Patel,
• Sarah Kishinevsky and
• Gabriela Chiosis

Beilstein J. Org. Chem. 2013, 9, 544–556, doi:10.3762/bjoc.9.60

• . It is obvious that much lower numbers of bulky streptavidin molecules can be attached on any solid support when compared to a low-molecular-weight ligand, such as PU-H71. Therefore, for isolation and identification of entire Hsp90 proteome isolations by mass spectrometry, as we recently reported [13

A peptidic hydrogel that may behave as a “Trojan Horse”

• Nicola Castellucci,
• Giorgio Sartor,
• Natalia Calonghi,
• Carola Parolin,
• Giuseppe Falini and
• Claudia Tomasini

Beilstein J. Org. Chem. 2013, 9, 417–424, doi:10.3762/bjoc.9.44

• 10.3762/bjoc.9.44 Abstract A physical hydrogel prepared with the low-molecular-weight hydrogelator (LMWHG) CH2(C3H6CO-L-Phe-D-Oxd-OH)2 and water/ethanol mixture was applied as a potential “Trojan Horse” carrier into cells. By SEM and XRD analysis we could demonstrate that a fibrous structure is present in

• confocal microscopy, fluorescent hydrogels were prepared, introducing the fluorescent dansyl moiety into the mixture. Keywords: amino acids; confocal microscopy; controlled release; hydrogel; low molecular weight hydrogelator; Introduction Drug delivery is an important topic in the finding of successful

• the cell membrane surface than does the β-sheet conformation [5]. Low-molecular-weight hydrogelators (LMWHGs) are defined as small molecules that self-assemble into long fibers, resulting in the formation of a gel [6][7][8][9][10]. Recently, several examples of peptide or peptidomimetic gelators have

Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• γ-methyl group of the threonine residue is required [12]. AFGPs are classified as small (AFGP6-8) and large AFGPs (AFGP1-5) depending on their electrophoretic properties. Low-molecular-weight AFGPs are supposed to adopt a threefold left-handed helix, which is highly flexible and similar to

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

• chains. Graft copolymers have found many applications, for example in the field of coatings, adhesives, compatibilizers, emulsifiers or biomaterials [1]. For the synthesis of graft copolymers, free radical copolymerization of macromonomers with suitable low molecular weight vinylmonomers is a widely

• voluminous vinylcyclopropane unit 5 possesses a slightly larger dn than 3 (by ca. 0.9 nm, Table 1). In general, the cloud point of poly(NiPAAm) with relative low molecular weight can be influenced by the structure of end groups. The relatively hydrophobic vinylcyclopropane end group hampers the aqueous

Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

Organocatalysis

• Benjamin List

Beilstein J. Org. Chem. 2012, 8, 1358–1359, doi:10.3762/bjoc.8.156

• -molecular-weight organic compounds, in which a metal is not part of the active principle. Organocatalysts donate or remove electrons or protons as their activation mode, hence defining four distinct subareas: Lewis base and Lewis acid catalysis on the one hand, and Brønsted base and Brønsted acid catalysis

• hand serves as the final report of this highly productive and successful “DFG Organokatalyse Schwerpunktprogramm, SPP 1179”. In addition, it captures the latest research activities in organocatalysis from many of the leading groups from all over the world. Organocatalysis describes catalysis with low

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• , but stabilization of the helix folding for small structures with less than 15 residues still remains a challenge [5][6]. Thus, new attempts have been made to design low-molecular-weight ligands that disrupt protein–protein interactions [7]. For example, fast proteolytic degradation observed with small

Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles

• Kathrin Fiege,
• Heinrich Lünsdorf,
• Sevil Atarijabarzadeh and
• Petra Mischnick

Beilstein J. Org. Chem. 2012, 8, 551–566, doi:10.3762/bjoc.8.63

• -molecular-weight reagents and by-products by dialysis and freeze dried. Samples with DS > 2 According to Onda [4], acrylonitrile (4.65 mL, 23 equiv/glc) and acetone (4.75 mL) were added to a solution of the polysaccharide (500 mg, 3.08 mmol glc 100 kDa pullulan or 6 kDa dextran) in water and NaOH (250 mg, 2

• , 7.4 mmol glc 100 kDa pullulan or 6 kDa dextran) was dissolved in water, and NaOH (60 mg, 0,2 equiv/glc) and acrylonitrile (1,941 μL, 4 equiv/glc) were added. In syntheses of CED-2 and CEP-2 1 mL, acetone was added. The mixture was stirred at 45 °C for 30 min. The product was purified from low

Synthesis of szentiamide, a depsipeptide from entomopathogenic Xenorhabdus szentirmaii with activity against Plasmodium falciparum

• Friederike I. Nollmann,
• Andrea Dowling,
• Marcel Kaiser,
• Klaus Deckmann,
• Sabine Grösch,
• Richard ffrench-Constant and
• Helge B. Bode

Beilstein J. Org. Chem. 2012, 8, 528–533, doi:10.3762/bjoc.8.60

• may be required for different stages of this life cycle, including the symbiotic stage (towards the nematode) or pathogenic stage (towards the insect prey) [1][2][3]. Until three years ago, the natural products extracted from Xenorhabdus and its close neighbour Photorhabdus were only low-molecular

• -weight compounds with UV chromophores (e.g., isopropylstilbenes [4], anthraquinones [4], or xenorhabdines [5]. However, bioactivity-based or MS-based screening of crude extracts and culture supernatants led to the identification of larger compounds, such as the PAX peptides [6], the xenortides [7

Synthesis of fluorinated maltose derivatives for monitoring protein interaction by ¹⁹F NMR

• Michaela Braitsch,
• Hanspeter Kählig,
• Georg Kontaxis,
• Michael Fischer,
• Toshinari Kawada,
• Robert Konrat and
• Walther Schmid

Beilstein J. Org. Chem. 2012, 8, 448–455, doi:10.3762/bjoc.8.51

• the affinities between the interaction partners. For example, small affinities or proteins with a relatively low molecular weight are more easily detected with high-affinity ligands, whereas strongly interacting proteins or high-molecular-weight protein ligands can be better studied with low-affinity

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• properties, rendering them interesting for a variety of specific applications [1][2][3][4][5][6][7][8][9][10][11][12][13]. Single substitutions of hydrogen by fluorine can change the biological effects of low-molecular-weight organic compounds tremendously, for example, unlike acetic acid, fluoroacetic acid

Synthesis and self-assembly of 1-deoxyglucose derivatives as low molecular weight organogelators

• Guijun Wang,
• Hao Yang,
• Sherwin Cheuk and
• Sherman Coleman

Beilstein J. Org. Chem. 2011, 7, 234–242, doi:10.3762/bjoc.7.31

• Guijun Wang Hao Yang Sherwin Cheuk Sherman Coleman Department of Chemistry, University of New Orleans, New Orleans, LA 70148, Phone: 504 280-1258, Fax: 504 280-6860 Dillard University, 2601 Gentilly Boulevard, New Orleans, Louisiana 70122 10.3762/bjoc.7.31 Abstract Low molecular weight gelators

• are an important class of molecules. The supramolecular gels formed by carbohydrate derived low molecular weight gelators are interesting soft materials that show great potential for many applications. Previously, we have synthesized a series of methyl 4,6-O-benzylidene-α-D-glucopyranoside derivatives

• synthesis and characterization of these novel analogs are reported. Keywords: 1,5-anhydroglucitol; carbohydrate; hydrogelator; organogelator; self-assembly; Introduction In recent years, the field of low molecular weight gelators (LMWGs) has received a great deal of attention. LMWGs are an interesting

Exceptionally small supramolecular hydrogelators based on aromatic–aromatic interactions

• Junfeng Shi,
• Yuan Gao,
• Zhimou Yang and
• Bing Xu

Beilstein J. Org. Chem. 2011, 7, 167–172, doi:10.3762/bjoc.7.23

• low molecular weight hydrogelators [24][25][26][27][28][29]. Despite the intensive research and rapid advances in the design and synthesis of low molecular weight hydrogelators, the minimum structural requirement for a small molecule to act as a hydrogelator to form supramolecular hydrogels has been

• date. Since phenylalanine derivatives belong to a class of insulin absorption promoters [34], this work not only provides a possible benchmark for low-molecular weight hydrogelators, but also a simple system to help in understanding the self-assembly of these phenylalanine based molecules in water and

• phenyl groups. Conclusion In summary, we have demonstrated that an aromatic group (fluorenyl, naphthyl, naphthalenoxyl, or cinnamoyl) covalently attached to phenylalanine gives rise to a series of new low molecular weight hydrogelators and the identification of the lowest molecular weight peptide-based