Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

• Timo Weinrich,
• Eva A. Jaumann,
• Ute M. Scheffer,
• Thomas F. Prisner and
• Michael W. Göbel

Beilstein J. Org. Chem. 2018, 14, 1563–1569, doi:10.3762/bjoc.14.133

• oligonucleotides were purified by anion exchange and reversed-phase HPLC and characterized by mass spectrometry (Supporting Information File 1, Figures S4–S9). Upon photochemical deprotection (365 nm), the primary products are the hemiacetals 22b–27b (Supporting Information File 1, Figure S10). They still prevent

Metal-free formal synthesis of phenoxazine

• Gabriella Kervefors,
• Antonia Becker,
• Chandan Dey and
• Berit Olofsson

Beilstein J. Org. Chem. 2018, 14, 1491–1497, doi:10.3762/bjoc.14.126

• from iodoarene 8 with anisole and mCPBA/TsOH [34] or via anion exchange of 5a were in vain. The O-arylation of 2-iodophenol (4) with salt 5a was investigated using our previously reported methodology [24][25]. As expected, the reaction proceeded well, both in THF and toluene, of which the latter was

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

• Jonas Weidner,
• Stefan Barwe,
• Kirill Sliozberg,
• Stefan Piontek,
• Justus Masa,
• Ulf-Peter Apfel and
• Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

• of the various cobalt–metalloid alloys supported on Ni RDE electrodes revealed CoB to be the most efficient HMF oxidation catalyst. Using a CoB modified Ni foam as anode material, and Ni foam as the cathode in a continuous flow reactor with an anion exchange membrane separating the anodic and

• continuous mode. For this, a flow reactor was employed which contains two nickel foam (NF) electrodes separated by an anion exchange membrane (Supporting Information File 1, Figure S2). The NF anode (1 cm × 1 cm) was modified with CoB by means of spray coating while pure NF was used as cathode material. The

• compartment and the CE compartment were separated by a PEEK reinforced anion exchange membrane (Fumatech). The CE consisted of two stacked unmodified Ni foams (1 cm × 1 cm) and a Hg/HgO/1 M KOH electrode served as RE. Catalyst modified NF (1 cm × 1 cm) was used as the WE. The potential was converted to the

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• utilization in fuel cells (FCs) converting chemical into electrical energy [5]. In alkaline FCs (AFCs) and proton exchange membrane FCs (PEMFCs), H2 and O2 are converted to H2O, heat and electricity. Since the development of anion exchange membranes the research interest in AFCs has increased again, because

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• exchanged against 10 mM sodium phosphate buffer, pH 5.5 by diafiltration (DV 20) and subsequently concentrated using an Amicon Ultra 15 mL centrifugal filter (MWCO 10 kDa). After centrifugation (overnight at 15,000 rpm and 4 °C), the soluble fraction was further purified using anion-exchange chromatography

Synthetic and semi-synthetic approaches to unprotected N-glycan oxazolines

• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 416–429, doi:10.3762/bjoc.14.30

• collected. Further purification by anion exchange chromatography (Sephadex DEAE eluting with NaCl) removed any non-sialylated glycans, and was followed by cation exchange chromatography (Sephadex C-25). Finally desalination using SEC (Sephadex G-25) gave pure SGP. Several improvements have subsequently been

Synthetic mRNA capping

• Fabian Muttach,
• Nils Muthmann and
• Andrea Rentmeister

Beilstein J. Org. Chem. 2017, 13, 2819–2832, doi:10.3762/bjoc.13.274

• release of the RNA. However, due to overall low coupling efficiencies and isolated yields (the compound was isolated in 20% overall yield after anion-exchange chromatography), this method was not used for large scale synthesis of capped RNA (Figure 6A). As the low reaction yields are mainly caused by the

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• received much attention in the organic catalysis for its excellent properties such as low costs, high specific surface area, double-layered structure, anion exchange capacity, high mechanical stability and chemical stability [38][39][40][41][42][43]. Our previous studies have proved that LDH catalysts

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• , redissolved in water (100 mL) and stirred with strongly basic anion exchange resin (Amberlite IRA 410 – OH− form, 100 mL, 68 g) for 1 hour. The resin was filtered and washed with water (2 × 100 mL). The filtrate was dried under reduced pressure using co-evaporation with EtOH. This crude material was dissolved

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• der Eycken et al. have synthesized 1-indanone 328 by utilizing 2-methylfuran (324) as a starting compound which was converted to the Mannich adduct 325, followed by the anion exchange reaction to give ammonium hydroxide 326

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• (50 mM Tris pH 8, 300 mM NaCl, 300 mM imidazole). For anion exchange chromatography (AEC), the Ni-NTA elution was buffer exchanged with AEC buffer A (see below) using illustra NAP-25 columns (GE Healthcare, Chalfont St Giles, UK) and concentrated using vivaspin® centrifugal concentrators with a 30 kDa

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• followed by anion exchange. The resultant oxocarbenium/tetraphenylborate ion pair undergoes a nucleophilic attack by silyl ketene acetal, which is followed by scavenging the trimethylsilyl cation with a chloride anion to result in chlorotrimethylsilane and the product. Mechanistic studies were conducted to

Synthesis, dynamic NMR characterization and XRD studies of novel N,N’-substituted piperazines for bioorthogonal labeling

• Constantin Mamat,
• Marc Pretze,
• Matthew Gott and
• Martin Köckerling

Beilstein J. Org. Chem. 2016, 12, 2478–2489, doi:10.3762/bjoc.12.242

• ); 19F NMR (376 MHz, CDCl3) δ −110.3; MS (ESI+) m/z (%): 752 (80) [M + H]+; Anal. calcd for C36H39ClFN7O6S (752.25): C 57.48, H 5.23, N 13.03; found, C 57.66, H 5.21, N 13.31. 4-(But-3-yn-1-yl)-1-(4-[18F]fluorobenzoyl)piperazine ([18F]4b): Similar as described in [47] an anion-exchange cartridge (Waters

• ). Analytical radio-HPLC: tR = 5.7 min (eluent: CH3CN/H2O, 15:85 + 0.1% TFA). 4-(3-Azidopropyl)-1-(4-[18F]fluorobenzoyl)piperazine ([18F]5b): Similar as described in [47] an anion-exchange cartridge (Waters, Sep-Pak Light Accell Plus QMA) was activated by rinsing with 5 mL of a 1 M NaHCO3 solution and 10 mL of

A new protocol for the synthesis of 4,7,12,15-tetrachloro[2.2]paracyclophane

• Donghui Pan,
• Yanbin Wang and
• Guomin Xiao

Beilstein J. Org. Chem. 2016, 12, 2443–2449, doi:10.3762/bjoc.12.237

• sodium hydroxide solution instead of silver oxide for anion exchange, results in a significant improvement in product yield. Furthermore, four substituted [2.2]paracyclophanes were also prepared in this convenient way. Keywords: bromination; dimerization; H2O2–HBr system; paracyclophane; polymerization

• with silver oxide for anion exchange was used [17], and it was comparable to the commercial synthetic protocol with 36.5% yield [20]. Although two isomers from the dimerization reaction could be formed, only the 4,7,12,15-tetrachloro isomer was obtained. The structure of the product was confirmed by 1H

• with silver oxide used for anion exchange reported by Chow [17]. We speculated that the replacement of silver oxide by aqueous sodium hydroxide solution might promote the formation of substituted (4-methylbenzyl)trimethylammonium hydroxide, but we are unable to provide any conclusive evidence at

DNA functionalization by dynamic chemistry

• Zeynep Kanlidere,
• Oleg Jochim,
• Marta Cal and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2016, 12, 2136–2144, doi:10.3762/bjoc.12.203

• imine products obtained in equilibrium into respective amines (Figure 2), thereby enabling the isolation and analysis of the library derived from oligonucleotide ON1. Anion exchange high-performance chromatography was used for the analysis of the final reaction mixture. The reaction mixtures were

• of the starting sequence CGCTATXTATCGC (ON1) and the product sequences (ON1+G, ON1+C, ON1+A, ON1+T) were identical differing only by one nucleobase in the central position X. As shown in Figure 4 all possible products were eluted as a mixture separated by anion exchange HPLC at 80 °C; under these

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• protonation or quaternization of neutral precursors (imidazoles, amines, phosphines, pyridine or sulfides) with Brønsted acids or haloalkanes/dialkylsulfates, respectively. In the next step, a variety of ionic liquids are obtainable by anion exchange, either through direct treatments with Lewis acids or by

• distillation reactor loaded with quaternary ammonium strongly basic anion exchange resin and alkali hydroxides: dimethyl carbonate (DMC) is achieved in practically quantitative yields (Scheme 6, bottom). The third and final step is the transesterification of DMC with phenol by a catalytic reactive distillation

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• (COD)Cl]2 and subsequent anion exchange with NaBArF (sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) led to the corresponding iridium precatalysts in high yields. These complexes as well showed high stability against oxygen and moisture and could be stored in air for several months without

• –76% yields (Scheme 7). From these ligands a library of iridium catalysts was prepared by complexation with bis(1,5-cyclooctadiene)diiridium(I) dichloride, followed by anion exchange with NaBArF. Comparative hydrogenation studies with iridium catalysts derived from 1st and 2nd generation NeoPHOX

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• catalyst induced polymerization of 5 in a living manner leading to a product with low polydispersity (1.12) and high molecular weight (167,000 g·mol−1). By substituting the PF6− anion with BPh4−, Cl− or an anion exchange resin (chloride-form), the authors demonstrated that the nature of the anion is

• aqueous media to evaluate them as luminescent markers of biological molecules. The production of metal-cation-based anion exchange membranes from ROMP polymers was first reported by Tew et al. [57]. The ROMP reaction, induced here by the Grubbs 2nd generation catalyst, implied the copolymerization of a

• membranes provided with single cation–anion pairs. Cross-linking with dicyclopentadiene ensured a high mechanical stability of the copolymer. The film cast from 28 displayed an anion conductivity and mechanical properties similar to those of the traditional quaternary ammonium-based anion exchange membranes

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• . After deprotection of the termini of the attached axles with trifluoroacetic acid (TFA), protonation of the free amines with HCl, and anion exchange with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF), the target compounds A2 and A4 were obtained. The weakly coordinating BArF counter-ion

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

• our group [11][12], the last stages of the multivalent probe synthesis involved the attachment of peracetylated azido iminosugars 4 on the scaffolds via CuAAC reaction and afterwards O-deacetylation using an anion exchange resin. First attempts to perform CuAAC reactions with triyne substrate 6b

• resulting from the cleavage of the carbon–boron bond in 6b. The same experimental protocol was applied to functionalized BODIPY 6a, leading to the desired trivalent cluster 12a in 83% yield. O-Deacetylation of compounds 12 using anion exchange Amberlite IRA-400 (OH−) resin provided the desired water-soluble

Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption

• Dominik Schmitt,
• Carolin Regenbrecht,
• Marius Hartmer,
• Florian Stecker and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 473–480, doi:10.3762/bjoc.11.53

• lignin research. So far most of the developed methods fail in technical application since no viable concept for work-up is included. This work represents a combined approach of electrochemical conversion of Kraft lignin and product recovery by adsorption on a strongly basic anion exchange resin

• ]. Consequently, such conversions are considered as reagent-free and avoid reagent waste [28][29][30]. We present a highly selective electrochemical approach providing an almost exclusive formation of vanillin (1) under very mild reaction conditions. The application of a strongly basic anion exchange resin allows

• solution and the moderate yields of 1 which can be achieved by these processes. Consequently, alternative concepts are necessary to allow product removal without precipitation of lignin and acidification of the whole reaction mixture. For this purpose the applicability of strongly basic anion exchange

A procedure for the preparation and isolation of nucleoside-5’-diphosphates

• Heidi J. Korhonen,
• Hannah L. Bolt and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2015, 11, 469–472, doi:10.3762/bjoc.11.52

• problems [4][19]. In addition, excess pyrophosphate is usually employed in order to drive the kinetics of the displacement process, however, this excess material tends to co-elute with nucleoside-5’-diphosphate products during anion exchange chromatographic purifications. We have recently reported the

Synthesis of divalent ligands of β-thio- and β-N-galactopyranosides and related lactosides and their evaluation as substrates and inhibitors of Trypanosoma cruzi trans-sialidase

• María Emilia Cano,
• Rosalía Agusti,
• Alejandro J. Cagnoni,
• María Florencia Tesoriero,
• José Kovensky,
• María Laura Uhrig and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 3073–3086, doi:10.3762/bjoc.10.324

• ’-sialyllactose as sialic acid donor, in the presence of the acceptor having βGalp non reducing ends. The products were analyzed by high performance anion exchange chromatography with pulse amperometric detection (HPAEC-PAD). The ability of the different S-linked and N-linked glycosides to inhibit the sialic acid

• aspect that has not been often exploited in previous reports. A preparative method based on anion exchange chromatography using AG1X2 resin, followed by analytical HPAE-PAD chromatography was optimized. The inhibitory behavior of the substrates for the transfer of sialic acid to the natural acceptor N

• donor and 1 mM of the substrate if not otherwise indicated. The reaction was analyzed by high pH anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) as shown in Figure 1 for the sialylation of 18. In all cases, the reaction was fast and reached the equilibrium in about 15 min

Reversibly locked thionucleobase pairs in DNA to study base flipping enzymes

• Christine Beuck and
• Elmar Weinhold

Beilstein J. Org. Chem. 2014, 10, 2293–2306, doi:10.3762/bjoc.10.239

• room temperature and pH 9.0 (Figure 1a and 1b). The reaction was monitored by denaturing anion exchange chromatography. Addition of urea to the elution buffers and heating of the column to 70 °C causes non-linked duplex ODN to dissociate and elute as their respective single strands while the covalently

• denaturing anion exchange HPLC. An aliquot of each cross-linked duplex was resuspended in buffer without reducing agent. The integrity of the purified cross-linked duplexes was assessed by denaturing HPLC (Figure 2b and Figure 3b). Both cross-linked duplexes elute at 13.4 min and show the characteristic low

• temperature in the absence of thiol reagents. Interestingly, when an aliquot of each cross-linked duplex is resuspended in buffer with 1 mM dithiothreitol (DTT) and analyzed by denaturing anion exchange HPLC, no more cross-linked duplex (retention time 13.4 min) is observed. Instead, the duplex dissociates

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• chloride, obtained from the condensation of TAG-Cl (1) and benzaldehyde, afforded 1,2,3-tris(benzylamino)guanidinium chloride [18]. This salt as well as other ones, obtained by anion exchange reactions, showed interesting solid-state structures, for example with anion-filled channels between layers

• no success either. According to a procedure by Casarini et al. [19] compound 5 could finally be obtained. This procedure uses dimethylaminoborane/p-toluenesulfonic acid, where the acid serves as an activator to release free borane. With a large excess of p-toluenesulfonic acid an anion exchange also