Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case

• Karina Mroczyńska,
• Małgorzata Kaczorowska,
• Erkki Kolehmainen,
• Ireneusz Grubecki,
• Marek Pietrzak and
• Borys Ośmiałowski

Beilstein J. Org. Chem. 2015, 11, 2105–2116, doi:10.3762/bjoc.11.227

• , CDCl3) for complex of 1 with substituted benzoates. The signal labelling for [1]:[5] in 1:1 ratio exemplified on the spectra recorded at −40 °C (CDCl3) and structure of complexes. The variable temperature (+20 to −40 °C, CDCl3) dependence of the main signals (the highest integral values) in 1d∙∙∙5

The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis

• Isabelle Sasaki,
• Jean-Claude Daran and
• Gérard Commenges

Beilstein J. Org. Chem. 2015, 11, 1781–1785, doi:10.3762/bjoc.11.193

• modifying the chelating properties of the polydentate ligands. Molecular view of compound 8 with the atom labelling scheme. Ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles of arbitrary radii. Molecular view of compound 9 using the atom labelling scheme. Selected

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• transfer of an electron to the TiO2 will compete with the loss of CO2, thus reducing yields. An intriguing aspect of the process is the source of the H atoms gained during the formation of adducts 22 and 29. This was not the proton lost from the aromatic ring in forming 31. Deuterium labelling experiments

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• carboxylates affords compounds 33a–c in moderate to good yields, whereas the reaction with NaN3 provided the ω,ω’-diazide 34. The latter compound served as interface for labelling with various alkyne-functionalized compounds. As proof-of-concept we successfully coupled 34 with the perylene derivative 35 to

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• -independent complex units of TMA·RSV·6.25H2O (A and B), with only the major component of disorder shown for RSV in host B (a), and the non-H atom and methylglucose ring nomenclature illustrated for host A as representative (b). For clarity, host H atoms have been omitted. Representative atomic labelling for

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• functional moiety is not prone to hydrolytic or enzymatic decay. Stable conjugation is an essential prerequisite for applications such as labelling or targeting. Here we report on the grafting of nitrogen-containing heterocyclic aromatic compounds using the Diels–Alder reaction of suitable starting materials

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• did not yield any product which suggested that there is a unique and exceptional degree of reactivity of the superoxide ion species which triggered this kind of reaction. To elucidate the reaction mechanism, we have performed a deuterium labelling experiment by treating 3c with KO2 in DMSO-d6 at rt

• reaction was derived through a controlled experiment with BHT which improved the yields of nortricyclenes and a deuterium labelling experiment using DMSO-d6. Further, acylation reactions of the synthesized methylenenortricyclens afforded the 2-propanone-substituted pentachloronorbornenes in good yields

Specific DNA duplex formation at an artificial lipid bilayer: fluorescence microscopy after Sybr Green I staining

• Emma Werz and
• Helmut Rosemeyer

Beilstein J. Org. Chem. 2014, 10, 2307–2321, doi:10.3762/bjoc.10.240

• left) during filling the syringes with buffer. C) Labelling of the single compartments and ports of the ‘Bilayer Slide’. These are disposable, optically transparent microfluidic sample carriers with perfusion capabilities. D) Schematic demonstration of the cis chamber perfusion. E) Shot of the device

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

• to contrast individual components in a multicomponent mixture through selective isotropic (hydrogen/deuterium) labelling. Research around a group of tri-chain surfactants has been carried out through the addition of a third extensively methylated tail in hope to both enhance CO2 compatibility and to

Asymmetric Ugi 3CR on isatin-derived ketimine: synthesis of chiral 3,3-disubstituted 3-aminooxindole derivatives

• Giordano Lesma,
• Fiorella Meneghetti,
• Alessandro Sacchetti,
• Mattia Stucchi and
• Alessandra Silvani

Beilstein J. Org. Chem. 2014, 10, 1383–1389, doi:10.3762/bjoc.10.141

• -substituted-3-aminooxindole core. ORTEP [37] view of one of the two independent molecules of 4a present in the asymmetric unit, showing the arbitrary atom-labelling scheme. Atomic displacement parameters for non-H atoms are at a probability level of 50%. Proposed explanation of the stereochemical outcome of

Molecular recognition of isomeric protonated amino acid esters monitored by ESI-mass spectrometry

• Andrea Liesenfeld and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 825–831, doi:10.3762/bjoc.10.78

• that has to be taken into account: non-covalent isotope effects [23] might also cause significant differences of the signals’ intensities. Therefore, every experiment has to be repeated with the different order of isotope labelling and in addition one should measure the same isomer in both forms – non

Self-assembly of metallosupramolecular rhombi from chiral concave 9,9’-spirobifluorene-derived bis(pyridine) ligands

• Rainer Hovorka,
• Sophie Hytteballe,
• Torsten Piehler,
• Georg Meyer-Eppler,
• Filip Topić,
• Kari Rissanen,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 432–441, doi:10.3762/bjoc.10.40

• homochiral assemblies by a factor of only two to three, this still reinforces our analysis – especially, if one takes into account that mass labelling in the periphery might cause differences in the ESI response factors that can cause slight deviations in the relative quantification of different components

[²H₂₆]-1-epi-Cubenol, a completely deuterated natural product from Streptomyces griseus

• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2841–2845, doi:10.3762/bjoc.9.319

• to slow down all metabolic processes in living organisms. Potential applications of completely labelled compounds from natural sources in structure elucidation, biosynthetic or pharmacokinetic investigations are discussed. Keywords: biosynthesis; deuterium; labelling; natural products; Streptomyces

• determination of the numbers of carbons and nitrogens in a natural product [28]. Therefore, such labelling experiments using a growth medium with a deuterium content of nearly 100% offer a suitable alternative to determine the number of hydrogens in an analyte, if no HRMS instrument is available. As pointed out

• in Bode’s study a labelling approach may even be more accurate for determination of the sum formula of a natural product, because a measured accurate mass may be in agreement with more than one molecular composition [28]. Completely deuterated compounds as exemplified by [2H26]-epi-cubenol in this

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• studies combined B3LYP density functional theory with labelling studies and revealed that the most likely pathway involves the formation of a tightly bound polar radical pair 3.31 resulting from

Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes

• Ana M. Sanjuán,
• Alberto Martínez,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2013, 9, 2242–2249, doi:10.3762/bjoc.9.263

• -(alkynyl)-(3-methylbut-2-enyl)benzenes 1. Gold(I)-catalyzed cycloisomerization of 1a. Initial experiments and proof of concept. Gold(I)-catalyzed hydroxycyclization of enynes 1m,n. Gold(I)-catalyzed methoxycyclization of selected 1,6-enynes 1 [45]. Labelling experiment and proposed mechanism. Effect of the

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• difference was observed between the performances of the two methods. Ferrocene-triazole conjugates play a crucial role in the labelling and detection of various systems, such as biomolecules, polymers, nanomaterials and supramolecular assemblies [70]. They also have potential applications in medicinal

Use of 3-[¹⁸F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

• Reik Löser,
• Steffen Fischer,
• Achim Hiller,
• Martin Köckerling,
• Uta Funke,
• Aurélie Maisonial,
• Peter Brust and
• Jörg Steinbach

Beilstein J. Org. Chem. 2013, 9, 1002–1011, doi:10.3762/bjoc.9.115

• Chemistry Group, Albert-Einstein-Straße 3a, 18059 Rostock, Germany 10.3762/bjoc.9.115 Abstract 3-[18F]Fluoropropanesulfonyl chloride, a recently proposed prosthetic agent for fluorine-18 labelling, was prepared in a two-step radiosynthesis via 3-[18F]fluoropropyl thiocyanate as an intermediate. Two

• benzenesulfonate-based radiolabelling precursors were prepared by various routes. Comparing the reactivities of 3-thiocyanatopropyl nosylate and the corresponding tosylate towards [18F]fluoride the former proved to be superior accounting for labelling yields of up to 85%. Conditions for a reliable transformation

• the application of the 18F-fluoropropansulfonyl group to the labelling of compounds relevant as imaging agents for positron emission tomography (PET), the stability of N-(4-fluorophenyl)-3-fluoropropanesulfonamide against degradation catalysed by carboxylesterase was investigated and compared to that

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• ) of GHB glucuronides 2 (top) and d4-2 (bottom). As anticipated, methylene protons b and c are absent in d4-2 (cf. labelling in Scheme 3). 1H NMR spectra (500 MHz) of GHB glucuronide 2 in pH 4.8 buffer at t = 0 (rt) and t = 72 h (90 °C) by using a Watergate-type water suppression method (Supporting

Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

• Dyanne L. Cruickshank,
• Natalia M. Rougier,
• Raquel V. Vico,
• Susan A. Bourne,
• Elba I. Buján,
• Mino R. Caira and
• Rita H. de Rossi

Beilstein J. Org. Chem. 2013, 9, 106–117, doi:10.3762/bjoc.9.14

• structure of fenitrothion (1). Representative TGA (top) and DSC (bottom) traces for DIMEB·1. The asymmetric unit in DIMEB•1 viewed along [010] (top) and [100] (bottom). H atoms are omitted for clarity. The host molecules in the asymmetric unit of DIMEB·1 with the labelling of both residues and atoms

An improved synthesis of a fluorophosphonate–polyethylene glycol–biotin probe and its use against competitive substrates

• Hao Xu,
• Hairat Sabit,
• Gordon L. Amidon and
• H. D. Hollis Showalter

Beilstein J. Org. Chem. 2013, 9, 89–96, doi:10.3762/bjoc.9.12

• the labelling efficiency of the FP–PEG–biotin probe 1 synthesized by our new route, we utilized it in the purification of four arbitrarily mixed proteins including bovine serum albumin (BSA), porcine carboxylesterase (pCES), nucleoside phosphorylase (NP), and trypsin (Figure 2A). Thus, the protein

• by the Cravatt group [21]. Kinetic study of FP probe labelling activity An incubation-time control study is the key toward successfully monitoring the competition between FP probe 1 and a reversible substrate with a high turnover rate. Hence, over a long incubation time, the substrate will be

• , blotted by streptavidin alkaline phosphatase, and visualized by incubation with ECF substrate. Kinetic study on FP labelling reactions. Caco-2 cell homogenates (1 mg/mL) were treated at room temperature with FP–PEG–biotin 1 (4 μM) for the indicated times, followed by the termination of reaction with 5

The Amadori rearrangement as glycoconjugation method: Synthesis of non-natural C-glycosyl type glycoconjugates

• Katharina Gallas,
• Gerit Pototschnig,
• Florian Adanitsch,
• Arnold E. Stütz and
• Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2012, 8, 1619–1629, doi:10.3762/bjoc.8.185

• surfaces (glycosylated surfaces, e.g., “glyco-chips”, gold, polystyrene plates, glass, nanoparticles), or labelling and imaging of carbohydrates (fluorescence markers, biotin, photolabelling) [27][28]. Herein we describe the application of the Amadori rearrangement as a key step for the synthesis of non

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• way, the synthetic sialosides can be easily conjugated to probes for biological evaluation or labelled for instance with UV-active tags. Biotinylation is a typical example of a commonly employed labelling technique [30] and has been extensively used for instance as a functionalization technique for

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• ]-cycloaddition under mild conditions. The template approach allows for the preparation of constructs that, e.g., combine biological activity, fluorescence labelling and cell-penetrating or cell-directing units in one molecule to be used for in vivo studies. The defined spatial organization of recognition units

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• use of galactose oxidase, which can be combined with different chemical modifications. Galactose oxidase is a copper-containing enzyme that catalyses the oxidation of the C6-hydroxyl group of nonreducing D-galactose residues [28][29]. Several subsequent modifications, such as site-specific labelling

• moieties. Labelling of 6-aldehydes of poly-LacNAc oligomers The 6-aldehyde products of poly-LacNAc oligomers 3a–c were further reacted with BACH (12) to incorporate a site-specific biotin label for subsequent detection of immobilised glycans. Conversion with 12 and subsequent reduction were performed

• of 10a showing the potential to produce terminally as well as internally oxidised and modified poly-LacNAc oligomers (11a). A: Labelling of poly-LacNAc oligomers 3a–c and 9a with biotin hydrazide derivative BACH (12) yielding the hydrazone products (13a–c and 14a); 13a–c and 14a were subsequently

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• polymers [21][22][23], and was used for DNA labelling [24][25], sensors [26][27], and metal chelates [28][29][30], due to the mild reaction conditions and compatibility with a variety of functional groups. However, the electronic conjugation through the resulting 1,2,3-triazole rings is weak due to poor