An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• ) was obtained in a yield of 85%. It was found to be important that after the debenzoylation the aqueous medium be neutralized with 0.1 M HCl under control of a pH-meter, to pH 7.2. Under the highly acidic conditions induced by a Dowex H+ ion-exchange resin, the free sulfate decomposes. The product was

• ion-exchange resin (Dowex WX8 H+) to yield 61% BGF (7) after recrystallization (Scheme 1). Analysis of cytotoxic effects of GSF toward human cells Two human melanoma cell lines, WM-115, isolated from a primary cancer, and WM-266-4, isolated from its cutaneous metastasis, were used to initially screen

Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols

• Marcin Jasiński,
• Dieter Lentz and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2012, 8, 662–674, doi:10.3762/bjoc.8.74

• yield (75%) by using ion-exchange resin DOWEX-50 at 50 °C (Table 2, entry 4). As shown for compound 8, simultaneous cleavage was also possible, and the analytically pure compound 14 was isolated in comparable yield (Table 2, entry 3). Alternatively, demethylation of 12 by treatment with boron tribromide

Ion-exchange-resin-catalyzed adamantylation of phenol derivatives with adamantanols: Developing a clean process for synthesis of 2-(1-adamantyl)-4-bromophenol, a key intermediate of adapalene

• Nan Wang,
• Ronghua Wang,
• Xia Shi and
• Gang Zou

Beilstein J. Org. Chem. 2012, 8, 227–233, doi:10.3762/bjoc.8.23

• addition of a slight excess of acetic anhydride during the work-up procedure, making the process waste-free except for regeneration of the ion-exchange resin, and facilitating the recycling of the resin catalyst. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and

• directly reused at least ten times without a significant loss of activity. The key intermediate of adapalene, 2-(1-adamantyl)-4-bromophenol, could be produced by means of this waste-free process. Keywords: adamantylation; ion-exchange resin; phenol; recycling; Introduction o-Adamantylphenols and their

• % after purification by chromatography) in 2 h (Table 1, entry 9). The control experiment showed that no reaction occurred in the absence of the acidic ion-exchange resin, clearly excluding the possibility of acetic acid catalysis in the adamantylation (Table 1, entry 12). When the loading of the resin

Continuous-flow hydration–condensation reaction: Synthesis of α,β-unsaturated ketones from alkynes and aldehydes by using a heterogeneous solid acid catalyst

• Magnus Rueping,
• Teerawut Bootwicha,
• Hannah Baars and
• Erli Sugiono

Beilstein J. Org. Chem. 2011, 7, 1680–1687, doi:10.3762/bjoc.7.198

• . Our initial reaction development was focussed on finding the optimal conditions for the continuous-flow reaction of phenylacetylene (1a) with benzaldehyde (2a) applying the ion-exchange resin amberlyst-15 [85] as heterogeneous solid acid catalyst. The effects of the substrate concentration, the

Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions

• Lukas Kupracz,
• Jan Hartwig,
• Jens Wegner,
• Sascha Ceylan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168

• azide we developed the iodine azide transfer reagent 5 based on ammonium iodate(I) complexes [25]. As depicted in Scheme 2 the reagent can be prepared in three steps without the generation of free iodine azide (1). Importantly, this reagent can easily be prepared as an ion-exchange resin based on

• trisubstituted alkenes 4h and 4i owing to the observed stereochemistry. Both of the functionalized polymers 5 and 8 are ideally suited for regeneration of the active species by employing simple flushing protocols without having to change the principal setup. Thus, azide-loaded ion-exchange resin 9, which is

• column chromatography (petroleum ether/ethyl acetate). Regeneration of functionalized polymer-bound iodate(I) complex 5 under flow conditions The reactor with azide-loaded ion-exchange resin 9 (5 g; theoretical loading = 3.5 mmol/g) was connected to the pump and, at the outlet side, to a collection flask

Synthesis of cationic dibenzosemibullvalene-based phase-transfer catalysts by di-π-methane rearrangements of pyrrolinium-annelated dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 119–126, doi:10.3762/bjoc.7.17

• salts of 2a–g have good solubility in aprotic polar solvents, especially in acetone and acetonitrile. To confer water-solubility on the cationic dibenzobarrelene derivatives 2b and 2d, the perchlorate salts were converted quantitatively to chlorides by ion exchange with chloride ions on an ion exchange

• resin. The photolysis of the cationic dibenzobarrelene derivatives 2a–d, which bear two identical N-alkyl substituents, was carried out in acetone solutions (λ > 310 nm), and the conversion of the dibenzobarrelene was monitored by 1H NMR spectroscopy. The dibenzosemibullvalene derivatives 3a–d were

A bivalent glycopeptide to target two putative carbohydrate binding sites on FimH

• Thisbe K. Lindhorst,
• Kathrin Bruegge,
• Andreas Fuchs and
• Oliver Sperling

Beilstein J. Org. Chem. 2010, 6, 801–809, doi:10.3762/bjoc.6.90

• overnight, the reaction mixture was neutralized by addition of ion exchange resin (Amberlite IR-120), filtered, the filtrate evaporated and the residue purified by reversed-phase chromatography on silica gel (H2O:MeOH = 1:5) to yield the title compound as a colourless lyophilisate (113 mg, 0.20 mmol, 82

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• solution in MeOH) in anhydrous MeOH (100 mL) were stirred at room temperature overnight. Water (100 mL) was added and the solution stirred for further 24 h. The mixture was then neutralized with acidic ion exchange resin containing formate ions (Amberlyte). The solvent was removed under reduced pressure

Chemical synthesis using enzymatically generated building units for construction of the human milk pentasaccharides sialyllacto-N-tetraose and sialyllacto-N-neotetraose epimer

• Dirk Schmidt and
• Joachim Thiem

Beilstein J. Org. Chem. 2010, 6, No. 18, doi:10.3762/bjoc.6.18

• has been reported in which sialylation with recombinant transsialidase (Trypanosoma cruzi) gave the trisaccharide 3 in 32% yield [8]. Treatment of 3 with methanol and acidic ion exchange resin led to the methyl ester (for the method cf. lit. [9]) which was then peracetylated to give trisaccharide 4 as

• units in all pentasaccharides for NMR assignment. Preparation of pentasaccharide 8. 1) MeOH, acidic ion exchange resin; 2) Ac2O, pyridine; 3) 80% HOAc, 90 °C; 4) NIS, CF3SO3H, 61%; 5) NiCl2•6H2O, H3BO3, EtOH, then NaBH4, EtOH and acidic workup. Preparation of pentasaccharide 14. 1) MeOH, acidic ion

• exchange resin; 2) Ac2O, pyridine; 3) 80% HOAc, 90 °C; 4) TBDPSCl, imidazole, DMF; 5) NIS, CF3SO3H, 53%; 6) NiCl2•6H2O, H3BO3, EtOH, then NaBH4, EtOH, then acidic workup; 7) CF3CO2H, CH2Cl2. Acknowledgements Support of these studies by the Deutsche Forschungsgemeinschaft (SFB 470, A5) and the Fonds der

Flow through reactors for organic chemistry: directly electrically heated tubular mini reactors as an enabling technology for organic synthesis

• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2009, 5, No. 70, doi:10.3762/bjoc.5.70

• temperature profile cannot be reached by traditional heating methods in an easy way. Kinetic measurements The applicability for kinetic measurements is demonstrated using a simple organic model reaction. We chose the hydrolysis of methyl formate with an ion exchange resin as an acidic heterogeneous catalyst

• both tubes. The first tube had a diameter of 1/8″ and a length of 50 cm. This tube was used as a non catalytic preheater. The second tube was 100 cm in length and had a diameter of 1/4″. It was filled with an ion exchange resin catalyst (Amberlyst 70, mean particle diameter 0.8–1 mm, ion exchange

• more than 100 bar are feasible. The applicability for kinetic measurements at temperatures above the normal boiling point was shown for the heterogeneously catalyzed hydrolysis of methyl formate. As an example the activation energy and rate constants for an industrial ion exchange resin catalyst were

Polyionic polymers – heterogeneous media for metal nanoparticles as catalyst in Suzuki–Miyaura and Heck–Mizoroki reactions under flow conditions

• Klaas Mennecke and
• Andreas Kirschning

Beilstein J. Org. Chem. 2009, 5, No. 21, doi:10.3762/bjoc.5.21

• heterogeneous supports for palladium(0) nanoparticles is described. These functionalized polymers were incorporated inside a flow reactor and employed in Suzuki–Miyaura and Heck cross couplings under continuous flow conditions. Keywords: Heck–Mizoroki reaction; heterogeneous catalysis; ion exchange resin

• high pressure/high temperature conditions aryl chlorides (for Suzuki–Miyaura reactions) or aryl bromides (for Heck–Mizoroki reactions) may very well serve as substrates for this kind of palladium species. Conclusion In summary, we demonstrated that polyionic gel 3 is a well suited ion exchange resin

m-Iodosylbenzoic acid – a convenient recyclable reagent for highly efficient aromatic iodinations

• Andreas Kirschning,
• Mekhman S. Yusubov,
• Roza Y. Yusubova,
• Ki-Whan Chi and
• Joo Y. Park

Beilstein J. Org. Chem. 2007, 3, No. 19, doi:10.1186/1860-5397-3-19

• . Separation of pure products is conveniently achieved by scavenging any aryl iodide by ion exchange with IRA-900 (hydroxide form). The reduced form of the reagent, m-iodobenzoic acid, can be easily recovered from the ion exchange resin or from the basic aqueous solution by simple acidification with HCl