Quantification of N-acetylcysteamine activated methylmalonate incorporation into polyketide biosynthesis

• Stephan Klopries,
• Uschi Sundermann and
• Frank Schulz

Beilstein J. Org. Chem. 2013, 9, 664–674, doi:10.3762/bjoc.9.75

• Accela HPLC-System (column Hypersil Gold, length 50 mm, inside diameter 1 mm, particle size 1.9 µm, ionization method: Electrospray Ionization). Products were characterized by NMR (1H, 13C) and HRMS. ESI-method for quantification of D3-label incorporation Mass-to-charge ratios of the extracts were

• particle size; Macherey-Nagel Germany) using a flow rate of 500 µL/min. Erythromycin: A linear gradient starting with 80% solvent A/20% solvent B for one minute and increasing to 0% solvent A/100% solvent B in 10 min. After that the column was washed with 0% solvent A/100% solvent B for 5 min and re

Zanthoxoaporphines A–C: Three new larvicidal dibenzo[de,g]quinolin-7-one alkaloids from Zanthoxylum paracanthum (Rutaceae)

• Fidelis N. Samita,
• Louis P. Sandjo,
• Isaiah O. Ndiege,
• Ahmed Hassanali and
• Wilber Lwande

Beilstein J. Org. Chem. 2013, 9, 447–452, doi:10.3762/bjoc.9.47

• electronic apparatus and are uncorrected. 1D and 2D NMR spectra were carried out on a Bruker DRX-300 MHz and Bruker 600 MHz instrument, respectively. Silica gels 60H (particle size < 45 µm), GF254 and 60A (size 70–200 µm) were used to perform, respectively, flash chromatography, thin-layer chromatography

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Synthesis and testing of the first azobenzene mannobioside as photoswitchable ligand for the bacterial lectin FimH

• Vijayanand Chandrasekaran,
• Katharina Kolbe,
• Femke Beiroth and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2013, 9, 223–233, doi:10.3762/bjoc.9.26

• charring with 10% sulfuric acid in EtOH followed by heat treatment at ~180 °C. Flash chromatography was performed on silica gel 60 (Merck, 230–400 mesh, particle size 0.040–0.063 mm) by using distilled solvents. Optical rotations were measured with a Perkin-Elmer 241 polarimeter (sodium D-line: 589 nm

A bisazobenzene crosslinker that isomerizes with visible light

• Subhas Samanta,
• Harris I. Qureshi and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2012, 8, 2184–2190, doi:10.3762/bjoc.8.246

• ) were used as received. NMR spectra were recorded either on Varian Vnmr-S 400 MHz, Varian Mercury 400 MHz or Agilent DD2 500 MHz spectrometers. Silica gel of particle size 40–63 μm from Silicycle Chemical Division was used for column chromatography. Synthesis of 1,4-diphenylpiperazine (7) [34]: A

S-Fluorenylmethyl protection of the cysteine side chain upon N^α-Fmoc deprotection

• Johannes W. Wehner and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2012, 8, 2149–2155, doi:10.3762/bjoc.8.242

• , Merck). Detection was effected by UV irradiation and subsequent charring with 10% sulfuric acid in EtOH followed by heat treatment. Flash chromatography was performed on silica gel 60 (230–400 mesh, particle size 0.040–0.063 mm, Merck). Preparative MPLC was performed on a Büchi apparatus by using a

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• polystyrene standards in a range of 575 to 3,114,000 g/mol. Toluene was used as the internal standard. Dynamic light scattering (DLS) experiments were carried out with a Malvern Zetasizer Nano ZS ZEN 3600 at a temperature of 20 °C. The particle size distribution was derived from a deconvolution of the

Multivalent display of the antimicrobial peptides BP100 and BP143

• Imma Güell,
• Rafael Ferre,
• Kasper K. Sørensen,
• Esther Badosa,
• Iteng Ng-Choi,
• Emilio Montesinos,
• Eduard Bardají,
• Lidia Feliu,
• Knud J. Jensen and
• Marta Planas

Beilstein J. Org. Chem. 2012, 8, 2106–2117, doi:10.3762/bjoc.8.237

• conditions with a Dionex UltiMate 3000 with Chromeleon 6.80SP3 software. Detection was performed at 215 nm. Peptide aldehydes and carbohydrate templates were analyzed with a Phenomenex Gemini 110 Å C18 (4.6 × 50 mm, 3 µm particle size) with a gradient of 5–80% B over 5 min and 80–100% B over 5 min (buffer A

• : 0.1% formic acid in H2O; buffer B: 0.1% formic acid in CH3CN) at a flow rate of 1 mL/min. Carbopeptides were analyzed on a C4 Phenomenex Jupiter 300 Å (4.6 × 150 mm, 5 µm particle size) with a gradient of 5–20% B over 2 min, 20–40% B over 8 min and 40–100% B over 2 min at a flow rate of 1 mL/min

• column (100 × 21.20 mm, 5 µm particle size) was used, running at a flow rate of 10.0 mL/min at room temperature with gradients from 5–55% B over 24 min and 55–100% B over 11 min (method A) and at 42 °C with gradients running from 5–50% B over 24 min, 50–95% B over 11 min and 95–100% B over 2 min (method

Cyclodextrin-induced host–guest effects of classically prepared poly(NIPAM) bearing azo-dye end groups

• Gero Maatz,
• Arkadius Maciollek and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 1929–1935, doi:10.3762/bjoc.8.224

• temperatures derived from these experiments were determined at 50% relative transmission. Dynamic light scattering (DLS) experiments were carried out with a Malvern Zetasizer Nano; ZS ZEN 3600 at a temperature of 20 °C. The particle size distribution is derived from a deconvolution of the measured intensity

Self-assembled organic–inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles

• Ângelo M. L. Denadai,
• Frederico B. De Sousa,
• Joel J. Passos,
• Fernando C. Guatimosim,
• Kirla D. Barbosa,
• Ana E. Burgos,
• Fernando Castro de Oliveira,
• Jeann C. da Silva,
• Bernardo R. A. Neves,
• Nelcy D. S. Mohallem and
• Rubén D. Sinisterra

Beilstein J. Org. Chem. 2012, 8, 1867–1876, doi:10.3762/bjoc.8.215

• determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe

• -Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer–Emmett–Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated

• components, organic and inorganic, and also on the synthesis process, which can be carried out by metal or organic hydrolyses [2][3]. Controlling the method of HM synthesis could lead to a predictable crystal structure and homogeneous particle size distribution [4]. Additionally, surface properties could be

Molecular solubilization of fullerene C₆₀ in water by γ-cyclodextrin thioethers

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2012, 8, 1644–1651, doi:10.3762/bjoc.8.188

• with C60. Particle sizes of C60 were determined by dynamic light scattering. Keywords: C60; cyclodextrins; dynamic light scattering; particle size; solubilization; UV spectrum; Introduction Since the first spectroscopic discovery of buckminsterfullerene, C60, by Kroto, Heath, Curl and Smalley in 1985

• ) investigations were performed to check for any aggregation during solubilization of C60 by γ-CD thioethers. DLS is a relatively fast method for the determination of the particle size distributions of proteins, polymers, micelles, and nanoparticles [46]. In particular, DLS is able to distinguish between a

• second to aggregates of it. Since the intensity of the scattered light increases with the sixth power of the particle size, the content of aggregates is highly overestimated [45]. For getting the right picture, this intensity profile had to be transformed to the volume distribution profile, by using the

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• particle size: 0.035–0.070 mm). NMR spectra were recorded on a Bruker Avance 300. FAB mass spectra were measured with a Micromass: ZabSpec. The enantiomeric excess of products was determined by chiral HPLC analysis in comparison with authentic racemic material. HPLC measurements were performed using

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

• ) or vanillin–sulfuric acid spray reagent (1% vanillin in 15% sulfuric acid). Column chromatography was performed on silica gel (63–200 mesh, particle size 60 Å, MP Biomedicals, Eschwege, Germany), Dowex WX8 H+ was from Serva, Heidelberg, Germany. Analytical HPLC was performed on a Jasco HPLC system by

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10

• Teresa Weise,
• Marco Kai,
• Anja Gummesson,
• Armin Troeger,
• Stephan von Reuß,
• Silvia Piepenborn,
• Francine Kosterka,
• Martin Sklorz,
• Ralf Zimmermann,
• Wittko Francke and
• Birgit Piechulla

Beilstein J. Org. Chem. 2012, 8, 579–596, doi:10.3762/bjoc.8.65

• . Purification by column chromatography on silica (ICN, pore size 60 Å, particle size 32–63 μm) with cyclohexane/ethyl acetate 20:1 followed by Kugelrohr distillation at 20 mmHg afforded 10-methylundecan-2-one (34) in a purity of 98%. Analytical data of the product were identical to those reported in the

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

• ), was 37.2 g/kg. The particle size was calculated by image data processing of the TEM micrograph resulting in a mean diameter of 12.2 nm ± 2.6 nm. The hydrodynamic diameter was estimated at 27 nm by dynamic light scattering (DLS) measurements. Agglomeration or aggregation processes were prohibited by pH

• ) and a reference iron, Fe(0) spectrum (dashed black line) [43]. The intensity is comparably low (Figure 12c) due to the particle size, exceeding the ideal thickness of 30 to 40 nm for EELS analysis. Nevertheless, a typical intensity profile of Fe L2,3 can be seen, at an energy resolution of 1.2 eV. The

• bidistilled water (ultrapure). Calibration was carried out with an external standard solution: Fe 10.000 mg/L (Specpure, Fa. Alfa Aesar). Particle size determination The hydrodynamic size was determined by using a Zetasizer Ver 6.0.1, Malvern Instruments Ltd. Scanning electron micrographs were recorded with a

Conserved and species-specific oxylipin pathways in the wound-activated chemical defense of the noninvasive red alga Gracilaria chilensis and the invasive Gracilaria vermiculophylla

• Martin Rempt,
• Florian Weinberger,
• Katharina Grosser and
• Georg Pohnert

Beilstein J. Org. Chem. 2012, 8, 283–289, doi:10.3762/bjoc.8.30

• measurements were performed on an UPLC–MS system equipped with a 2996 PDA detector and a Q-tof micro ESIMS (Waters, Manchester, UK). For separation of the analytes, a BEH C18 column (2.1 × 50 mm, particle size 1.7 µm) was used. LC on a semipreparative column was carried out by using a LC-8A liquid

• chromatography system from Shimadzu (Duisburg, Germany) equipped with a SPD-10AV UV–vis detector. A Licro Chart® 250-10 Purosphere® RP-18 endcapped column (particle size 5µm) supplied by Merck (Darmstadt, Germany) was used for separation. HPLC separation on an analytical scale was performed on the same LC system

• equipped with a Synergi MAX-RP 250 × 4.6 mm column (particle size 4 µm) from Phenomenex (Macclesfield, UK). Optical rotations were measured on a Jasco (Groß-Umstadt, Germany) 1030 polarimeter at 589 nm. Circular-dichroism spectra were recorded on a Jasco P810 instrument. Analytical thin-layer

Highly efficient cyclosarin degradation mediated by a β-cyclodextrin derivative containing an oxime-derived substituent

• Michael Zengerle,
• Florian Brandhuber,
• Christian Schneider,
• Franz Worek,
• Georg Reiter and
• Stefan Kubik

Beilstein J. Org. Chem. 2011, 7, 1543–1554, doi:10.3762/bjoc.7.182

• , BetaBasic-18, 250 × 21.2 mm, 5 μm particle size; flow, 12 mL/min; eluent, aqueous: 0.025% aqueous ammonia, organic: acetonitrile; for the separation of neutral compounds (1a, 2b–2d) the following gradient was used: 0–6 min, 0% organic; 6–27 min, linear increase of organic to 40%; 27–33 min, 40% organic; 33

Chiral recognition of ephedrine: Hydrophilic polymers bearing β-cyclodextrin moieties as chiral sensitive host molecules

• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1516–1519, doi:10.3762/bjoc.7.177

• ) experiments were carried out with a Malvern High Performance Particle Sizer HPPS-ET at a temperature of 20 °C in aqueous solutions of copolymer 1 (1 mg/mL) and ephedrine (1 mg/mL). The particle size distribution is derived from a deconvolution of the measured intensity autocorrelation function of the sample

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

• Alicja Schlange,
• Antonio Rodolfo dos Santos,
• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2011, 7, 1412–1420, doi:10.3762/bjoc.7.165

• conventional method (oil bath) the samples synthesized in the tubular reactor show a more uniform distribution of the platinum cluster size (average particle size of 1.80 nm) without any agglomerates over the carbon support. The metal dispersion of the described catalyst (16.49%) is much higher than for the

Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

• Marian C. Bryan,
• David Wernick,
• Christopher D. Hein,
• James V. Petersen,
• John W. Eschelbach and
• Elizabeth M. Doherty

Beilstein J. Org. Chem. 2011, 7, 1141–1149, doi:10.3762/bjoc.7.132

• technique [17][18]. For example, Makkee and coworkers conducted a thorough investigation of the challenges associated with the scaling down of a “trickle bed” flow hydrogenator [19] and showed that both particle size homogeneity and column packing technique [18][20] have an impact on the conversion and the

• with a new 30 mm 10% Pd/C CatCart® (from the same lot) to give 16 μg of Pd in the first 10 mL wash solvent. While this mass accounts for only ~0.1% of the average 150 mg catalyst loading per cartridge, the particle size is apparently very small and thus the relative catalytic activity is enhanced [25

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• in a temperature range from 6 to 50 °C. The particle size distribution was derived by deconvoluting the measured intensity autocorrelation function of the sample with the NNLS general purpose mode algorithm included in the DTS software. UV–vis spectra were recorded in water using the UV 540 system of

Multicomponent reaction access to complex quinolines via oxidation of the Povarov adducts

• Esther Vicente-García,
• Rosario Ramón,
• Sara Preciado and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2011, 7, 980–987, doi:10.3762/bjoc.7.110

• conditions with an old (≈40 years) MnO2 sample of unknown origin (particle size 11.46 µm, see below). A promising result was obtained, achieving a 39% conversion to the desired product 18, albeit with a high ratio of the elimination–oxidation compound 19. Next, the equivalents of oxidant and pyridine were

• decided to test different commercially available MnO2 sources (Aldrich, Acros and Wako) of distinct activation degrees (particle size, powder or activated reagent, Table 1) in order to find a suitable reagent leading to comparable results. Aldrich MnO2 (reagent grade) did not afford the desired quinoline

• –oxidation product did not decrease. We then analysed the particle size of all samples using a laser diffraction technique (see Supporting Information File 1). Although a straightforward conclusion is not evident, it seems that all samples with a small (around 4 µm) or large particle size (138 µm) were

A gold-catalyzed alkyne-diol cycloisomerization for the synthesis of oxygenated 5,5-spiroketals

• Sami F. Tlais and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2011, 7, 570–577, doi:10.3762/bjoc.7.66

• purification. All reactions were carried out under an inert nitrogen atmosphere unless otherwise stated. Purifications were performed by flash chromatography on silica gel F-254 (230–499 mesh particle size). Typical procedure for gold-catalyzed spiroketalization: AuCl (8 mg, 0.036 mmol) was added to a solution

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• ) in positive or negative mode. Analytical HPLC analysis was carried out on a Shimadzu LC-20 system with a LiChrospher 100 C18 reversed–phase analytical column (119 × 3 mm, 5 µm particle size) at 25 °C, using mobile phase A (water/MeCN 9:1 (v/v) + 0.1% TFA) and phase B (MeCN + 0.1% TFA), with linear

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• continuous flow of hydrogen gas [43]. The scanning electron microscope image shows that particle size of the catalyst is ~100 to 300 nm (Supporting Information File 1). The X-ray photoemission spectra confirms the formation of metallic Pd(0) particles, the binding energy values were 335.3 and 340.5 eV for Pd