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

• solvents, like dioxane and CH2Cl2, is decreased and the deprotection has to be carried out in trifluoroacetic acid (TFA), followed by a subsequent anion exchange by dialysis of the polymer solution against aqueous sodium chloride and water. 7b was prepared from the polycation 6 by alkaline treatment, but

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

• picrate to 9a indeed dramatically simplified the 1H NMR spectrum by inducing the formation of a sodium complex with a 6-fold symmetry (Figure 2ii). Subsequent O-deacetylation of compounds 9 using anion exchange Amberlite IRA-400 (OH−) resin provided the final deprotected iminosugar clusters 10 in high

Synthesis of nucleotide–amino acid conjugates designed for photo-CIDNP experiments by a phosphotriester approach

• Tatyana V. Abramova,
• Olga B. Morozova,
• Vladimir N. Silnikov and
• Alexandra V. Yurkovskaya

Beilstein J. Org. Chem. 2013, 9, 2898–2909, doi:10.3762/bjoc.9.326

• nucleotide block 17. After the deprotection, target conjugates 1–8 were purified by the anion exchange and reversed phase chromatography (RPC) at a medium pressure, which provides the high purity of the final products and easy scaling up in laboratory conditions. The homogeneity and structures of all key

• using Kieselgel 55–100 μm (Merck, Germany); RPC, a Porasil C 18 (55–105 μm, 125 A) (Waters, USA); and anion exchange chromatography, DEAE Sephadex A-25 (Pharmacia, Sweden). Eluent composition is given in v/v per cent. NMR spectra were acquired on Bruker AM-400 and AV-300 instruments (Bruker, Germany) in

• M solution of TBAF in 50% aqueous Py (pH 7.0, 1.0 mL per 0.05 g of the fully protected derivative) and stirred at 40 °C overnight. The reaction mixtures were then evaporated several times with water to remove Py. The subsequent purification of products by anion exchange chromatography and RPC

Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals

• Martin Butschies,
• Manuel M. Neidhardt,
• Markus Mansueto,
• Sabine Laschat and
• Stefan Tussetschläger

Beilstein J. Org. Chem. 2013, 9, 1093–1101, doi:10.3762/bjoc.9.121

• sulfonimide anion directly attached to the mesogenic unit. Keywords: anion exchange; ionic liquid crystals; ion pairs; mesophases; sulfonimides; Introduction While ionic liquids, i.e., molten salts composed of either organic cation or anion (or both) with melting points far below 100 °C, are extensively

• [38], because we wanted to avoid the activation with dimethyl sulfate reported by DesMarteau [21]. Therefore we planned an indirect formation of the ion pairs by anion exchange via salt metathesis. In order to be successful, two requirements have to be met. First, the solubility of the sulfonimide

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

• corresponding homoleptic Ru(II) complexes 1 and 2 in 55–60% yield as red solids after chromatographic purification. Anion exchange to form the corresponding hexafluorophosphates was achieved through precipitation from a saturated methanolic solution of NH4PF6 (Scheme 3). All compounds were characterized by NMR

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• depicted in Figure 2, high pH anion exchange chromatography with pulse amperometric detection (HPAEC–PAD) showed that the synthetic disaccharide (Figure 2B) coeluted with the natural product (Figure 2C). Conclusion In conclusion, we have reported a very simple procedure for the synthesis of Glcp(1→2)-α-D

• pulse amperometric detector (PAD). The detector was set at 30 nA and E1 = +10.05 V, E2 = +10.60 V, and E3 = −0.60 V. The column used was a CarboPac PA-10 anion-exchange analytical column (4 × 250 mm), equipped with a guard column PA-10 (5 × 50 mm). The following conditions were used: Condition 1

Hybrid super electron donors – preparation and reactivity

• Jean Garnier,
• Douglas W. Thomson,
• Shengze Zhou,
• Phillip I. Jolly,
• Leonard E. A. Berlouis and
• John A. Murphy

Beilstein J. Org. Chem. 2012, 8, 994–1002, doi:10.3762/bjoc.8.112

• bromide (16) [34] with N-methylimidazole (17) afforded disalt 19. Deprotonation with NaH (15 equiv) in DMF then afforded the electron donor 11 in situ; this was reacted with iodine to afford the oxidised diiodide salt, and this was subjected to anion exchange to afford the bis(hexafluorophosphate) salt 21

• for analysis. (Anion exchange to bis(hexafluorophosphate) salts was required since the iodide anions within diiodide salts would be electrochemically active in CV studies). To verify the intermediacy of 11, its formation from 19 was repeated in DMF-d7, and the 1H and 13C NMR spectra of 11 were

The role of silver additives in gold-mediated C–H functionalisation

• Scott R. Patrick,
• Ine I. F. Boogaerts,
• Sylvain Gaillard,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2011, 7, 892–896, doi:10.3762/bjoc.7.102

• factors must also be considered to rationalise the anomalous activity of AgI. The Lewis acidity of the silver salts may contribute to initiate the reaction [22], but unsuccessful reactions using Al2O3, AlCl3, Cu2O or ZnBr2 proved otherwise. The existence of a transient anion exchange between the gold (AuX

Fluorometric recognition of both dihydrogen phosphate and iodide by a new flexible anthracene linked benzimidazolium-based receptor

• Kumaresh Ghosh and
• Debasis Kar

Beilstein J. Org. Chem. 2011, 7, 254–264, doi:10.3762/bjoc.7.34

• to afford the diamide 4 in 80% yield. Subsequent reaction of 4 with anthracene coupled benzimidazole 3 (prepared in 64% yield from benzimidazole and 9-chloromethylanthracene in the presence of NaH in dry THF) gave the dichloride salt 5 in 55% yield. Anion exchange using NH4PF6 in warm aqueous CH3OH

• gave the desired compound 1 in 90% yield. Similarly, model compound 2 was obtained in 64% yield from the reaction between 6 and 3 in dry CH3CN followed by anion exchange using NH4PF6 in aqueous CH3OH. All the compounds were characterized unequivocally by 1H NMR, 13C, mass spectrometry and FTIR. In

• precipitated chloride salt was filtered, washed with water and dried (0.51 g, 64.4%). The compound 6 in MeOH was subsequently treated with aqueous NH4PF6 solution to carry out the anion exchange reaction. The solution was heated with stirring for 20 min until a precipitate appeared. Filtration of the

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• with 4-nitrophenyl isocyanate (obtained from 4-nitroaniline by reaction with triphosgene in dry THF) in dry THF to give urea derivative 5. Subsequent reaction of 5 with 9-chloromethylanthracene under refluxing conditions in dry CH3CN gave the chloride salt 6. Anion exchange of the salt 6 with NH4PF6

• afforded the desired receptor 1 as a white solid. Compound 2 was obtained from the intermediate amine 4 after performing a series of reactions such as amide formation, alkylation on pyridine ring nitrogen followed by anion exchange with NH4PF6 (Scheme 1b). Compounds 1 and 2 were characterized by 1H NMR

Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates

• Milena Trmčić and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2010, 6, 732–741, doi:10.3762/bjoc.6.87

• Sepharose FF column (500 ml bed volume, in a 30 × 5 cm column). Anion exchange chromatography was performed using a linear gradient of triethylammonium bicarbonate solution (50–600 mM) pH 7.6 [15], over 2 h at a flow rate of 30 mL/min using an Äkta Plus chromatography system. Fractions containing the

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• dication 16, and hence make formation of 16 more difficult. To determine the effect of bridge-length on redox potential, the analogous donors 14 and 15 were prepared in situ and converted to their respective oxidized salts 16 and 18, as shown in Figure 2, by reaction with iodine. Anion exchange to afford

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• high yield by treatment of telluride starting material with an equimolar mixture of triflic anhydride and DMSO at 0 °C. Anion exchange was easily accomplished with silver tetrafluoroborate to afford 8 (Scheme 3) [13]. To increase the electrophilicity of salts 5–8, the salts were nitrated with nitronium

• , 2-(phenyl)phenyl trifluoromethyl sulfoxide was converted into the corresponding sulfonium salt by treatment with an excess amount of 60% SO3·H2SO4 at 0 °C followed by hydrogen sulfate anion exchange with tetrafluoroborate or triflate ion (Scheme 11). Increasing the reaction temperature during

1-(4-Alkyloxybenzyl)-3-methyl-1H-imidazol-3-ium organic backbone: A versatile smectogenic moiety

• William Dobbs,
• Laurent Douce and
• Benoît Heinrich

Beilstein J. Org. Chem. 2009, 5, No. 62, doi:10.3762/bjoc.5.62

• , respectively. Mesogenic imidazolium synthesis [Reaction conditions: (i) DMF, K2CO3, BrCnH2n+1, 60 °C, overnight; (ii) LiAlH4, THF, Ar, 4 h; (iii) SOBr2, DCM, under Ar; THF dry, methylimidazole, inert atmosphere]. Anion exchange in water. Temperatures and enthalpy changes of the phase transitions for 18–10 to

A convenient method for preparing rigid-core ionic liquid crystals

• Julien Fouchet,
• Laurent Douce,
• Benoît Heinrich,
• Richard Welter and
• Alain Louati

Beilstein J. Org. Chem. 2009, 5, No. 51, doi:10.3762/bjoc.5.51

• /4H2O, Calcd: C, 55.64; H, 7.53; N, 5.90%. Found: C, 55.78; H, 7.48; N, 5.34%. General procedure for metathesis in water–anion exchange A mixture of 1a dissolved in dichloromethane (4 mL) and a mixture of the corresponding salts dissolved in water (3 mL) were stirred together for 140 h. The organic

Synthesis of 3-(phenylazo)-1,2,4-triazoles by a nucleophilic reaction of primary amines with 5-chloro- 2,3-diphenyltetrazolium salt via mesoionic 2,3-diphenyltetrazolium- 5-aminides

• Shuki Araki,
• Satoshi Hirose,
• Yoshikazu Konishi,
• Masatoshi Nogura and
• Tsunehisa Hirashita

Beilstein J. Org. Chem. 2009, 5, No. 8, doi:10.3762/bjoc.5.8

• ][7]. Thus, the treatment of 2,3-diphenyltetrazolium-5-olate with phosphorus oxychloride gave 2 in high yield as stable crystals, after an anion exchange to tetrafluoroborate. Next, the reactions of 2 with various amines were examined. When 2 was treated with benzylamine in dichloromethane in the