bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of a SLex mimic: A potential E‐selectin binding antagonist
Authors: Heskamp B. M. , Veeneman G. H. , van der Marel G. A. , van Boeckel C. A. A. , van Boom J. H. 
Published: September 2010

AbstractIodonium‐ion‐assisted condensation of methyl 4,7,8,9‐tetra‐O‐acetyl‐N‐acetyl‐2‐O‐[3‐ (methylthiomethoxy)propyl]‐α‐D‐neuraminate (15) with hexyl 2‐acetamido‐6‐O‐benzyl‐3‐O‐(tri‐O‐ benzyl‐α‐L‐fucopyranosyl)‐2‐deoxy‐β‐D‐glucopyranoside (12) furnished, after deprotection, SLex mimic 3. The non‐fucosylated derivative 2 was obtained in a similar fashion by the coupling of 15 with hexyl 2‐acetamido‐3‐O‐benzoyl‐6‐O‐benzyl‐2‐deoxy‐β‐D‐glucopyranoside (8).
Synthesis, X‐ray structure, spectroscopic and cation complexation studies of macrocyclic ligands incorporating the 9,9′‐(ethane‐1,2‐diyl)bis(anthracene) photoactive subunit
Authors: Desvergne J.‐P. , Lauret J. , Bouas‐Laurent H. , Marsau P. , Lahrahar N. , Andrianatoandro H. , Cotrait M. 
Published: September 2010

AbstractTwo 9,9′‐(ethane‐1,2‐diyl)bis(anthracene) ligands, incorporating an ethano bridge, namely the bis‐anthracene coronand 1 and the bis‐anthracene cryptand 2, respectively, have been studied in parallel to compare their binding abilities, spectroscopic and photochemical properties in the presence and absence of cations as a function of their X‐ray structure. The ethano bridge imposes a twisted shape (torsion angles between the vicinal C‐H being 47° for 1 and 62° for 2a and 47° for 2b, the two conformers of compound 2), which inhibits the cation‐binding ability of 1 and attenuates that of cryptand 2 (log Ks ≈︁ 1.8 for Na+ or K+, ≈︁ 4 for Tl+ and ≈︁ 8 for Ag+); in CH3OH, both 1 and 2 emit essentially excimer‐type fluorescence at λmax 520‐535 nm, which is red‐shifted compared with that of the single crystals ( ≈︁ 465‐480 nm) where the rotation about the CH2‐CH2 bond is hindered. The presence of cations, which has no influence on the photocycloisomerization quantum yield of 1 (as expected), clearly affects that of 2. Cryptand 2 was shown to display photochromic properties.
New intrinsic fluoroionophores with dual fluorescence: DMABN‐Crown4 and DMABN‐Crown5
Authors: Létard J.‐F. , Delmond S. , Lapouyade R. , Braun D. , Rettig W. , Kreissler M. 
Published: September 2010

AbstractTwo new intrinsic fluoroionophores, with the electronic structure of 4‐(dimethylamino)‐ benzonitrile (DMABN): 4‐(1‐aza‐4,7,10‐trioxaclyclododecyl)benzonitrile (DMABN‐Crown4) and 4‐(1‐aza‐4,7,10,13‐tetraoxacyclopentadecyl) benzonitrile (DMABN‐Crown5) were synthesized and their absorption, fluorescence spectra and quantum yields of fluorescence measured and discussed. Comparison of X‐ray data and calculations from the density functional theory (DFT) shows that from DMABN to DMABN‐Crown5 the twist angle of the amino group with respect to the phenyl plane increases while the pyramidalization of the nitrogen is not significantly affected. The activation energies (Ea 8.9 kJ · mol−1, Ed 23.7 kJ · mol−1) and the enthalpy (ΔH‐14.8 kJ · mol−1) involved between the LE and TICT states of DMABN‐Crown5 were obtained in toluene and compared with those previously published for DMABN. The greater relief of strain (larger ΔH) which accompanies the formation of the TICT state in the crown derivatives, accounts for the higher proportion of TICT emission recorded at room temperature. The fluorescence of DMABN‐Crown5 in acetonitrile, is altered significantly at 3 · 10−4 mol · 1−1 of Ca2+: the long‐wavelength emission from the TICT state decreases while the short‐wavelength emission increases. From the wholly complexed probes, the two emissions are blue‐shifted relative to those of the free probe and originate from contact‐ and/or solvent‐separated probe‐cation pair with the probe in the LE and in the TICT state. Similarly, the fluorescence spectrum of DMABN‐Crown4, in acetonitrile, is altered significantly when Mg(CIO4)2 is added in concentrations of 5 · 10−3 mol · 10−1 or above.
Some aspects of the role of amines in the photoinitiated polymerisation of acrylates in the presence and absence of oxygen
Authors: Bradley Grant , Davidson R. Stephen 
Published: September 2010

AbstractTriethanolamine (1), N‐methyldiethanolamine (2) and N,N‐dimethylethanolamine (3) have been used in conjunction with the 2‐(2‐chlorophenyl)‐4,5‐diphenylimidazolyl radical and triplet benzophenone to initiate the polymerisation of lauryl acrylate. The radical abstracts a hydrogen atom from the amine to generate an α‐aminoalkyl radical. From the order of reactivity of the amines towards the lophyl (triarylimidazolyl) radical i.e. 2 >> 1 > 3 it is concluded that hydrogen‐atom abstraction occurs rather than electron followed by proton transfer. The imidazolyl radicals abstract hydrogen from thiols in a similar fashion more effectively to give thiyl radicals which initiate polymerisation of the acrylate. By following the progress of the polymerisation reactions by RTIR spectroscopy, it was concluded that the effectiveness of the amines to reduce oxygen inhibition is 1 < 3 < 2. The ability of the amines to act as synergists in the polymerisation of thin films of lauryl acrylate initiated by lophyl radicals and triplet benzophenone was assessed. The efficiency of the amines was found to be 2 ∼ 1 > 3 for reaction with lophyl radicals whereas with triplet benzophenone the three amines gave similar amounts of polymer. For amines 2 and 3, two types of amino alkyl radical can be generated. It is concluded that radicals of type > NCHCH2OH are more effective initiators than CH2N <.
Synthesis of (R)‐ and (S)‐2‐hydroxy‐3‐enoic acid esters
Authors: Warmerdam E. G. J. C. , van den Nieuwendijk A. M. C. H. , Brussee J. , van der Gen A. , Kruse C. G. 
Published: September 2010

AbstractThe synthesis of (R)‐ and (S)‐2‐hydroxy‐3‐enoic acid esters [(R)‐1a‐d and (S)‐1a‐c] is described. The (R) enantiomers were prepared by a Pinner synthesis from the corresponding (R)‐cyanohydrins [(R)‐2a‐d], which in turn were obtained by R‐oxynitrilase‐ (E.C. 4.1.2.10)‐catalyzed addition of HCN to the α,β‐unsaturated aldehydes 3a‐d. For the preparation of the (S) enantiomers an inversion of the configuration had to be implemented. A critical evaluation of the two possible sequences: inversion of the configuration of the cyanohydrins followed by solvolysis of the nitrile function, and solvolysis of the cyanohydrins followed by inversion of the configuration of the resulting α‐hydroxy esters, came out in favor of the latter pathway.
Synthesis of pyridopyrazino[2,3‐b]indoles and 10H‐indolo[3,2‐g]pteridins
Authors: Bergman Jan , Vallberg Hans , Damberg Charlotta 
Published: September 2010

AbstractThe reactions between isatin (8a) and N‐acetylisatin (8b) with pyridine‐2,3‐diamine (9a), pyridine‐3,4‐diamine (9b) and pyrimidine‐4,5‐diamine (21) were studied. 10H‐Pyrido[3′,2′:5,6]pyrazino[2,3‐b]indole (5a), 6H‐pyrido[2′,3′:5,6]‐pyrazino[2,3‐b]indole (5b), 6H‐pyrido[3′,4′:5,6]pyrazino[2,3‐b]indole (5c) and 10H‐pyrido[4′,3′:5,6]pyrazino[2,3‐b]indole (5d) were regioselectively synthesized in a three‐step synthesis from N‐acetylisatin and the appropriate pyridine diamine. The structures of the intermediates were assigned by NOESY experiments. In the same manner, 10H‐indolo[3,2‐g]pteridine (24) was synthesized from N‐acetylisatin and pyrimidine‐4,5‐diamine.
The effects of chain flexibility on the properties of vesicles formed from di‐n‐alkyl phosphates
Authors: Smits Elly , Engberts Jan B. F. N. , Blandamer Michael J. , Briggs Barbara , Cullis Paul M. 
Published: September 2010

AbstractThis paper describes a study of the effects of chain flexibility and chain packing on the properties of vesicles formed from sodium di‐n‐alkyl phosphates. Three di‐n‐alkyl phosphates with a constant chain length but with different degrees of unsaturation have been synthesized: dioleyl phosphate (DOP) and dielaidyl phosphate (DEP) having, respectively, a cis and a trans double bond at C‐9 and the saturated distearyl phosphate (DSP). These surfactants form vesicles, as confirmed by transmission electron microscopy (EM). The gel to liquid‐crystalline phase transition was studied using both fluorescence polarization and differential scanning microcalorimetry. According to fluorescence polarization, using trans, trans, trans‐1,6‐diphenyl‐hexa‐1,3,5‐triene (DPH) as a probe, DSP vesicles undergo a cooperative transition from a gel to a liquid‐crystalline state at 72°C. The polarization of the probe captured in DOP or DEP vesicles decreased gradually in the temperature range 0–40°C, indicating a non‐cooperative phase transition. It appears that the vesicle bilayer is in a gel state below 0°C and in a liquid‐crystalline state above 40°C. A temperature‐dependent 31P NMR study failed to identify the exact phase‐transition temperature. The effect of the fusogenic cation Ca2+ was studied qualitatively using EM. Calcium induces fusion of DEP vesicles but, within a short time, tubules are formed which are most probably anhydrous crystals of the calcium salts. For DSP vesicles the latter process is extremely fast and fused vesicles cannot be detected. In contrast, DOP vesicles fuse under the influence of calcium, but no crystallization takes place. The fused DOP vesicles are stable for more than one week in the presence of 4 mM Ca2+ stored at room temperature or at 60°C. Addition of EDTA to DOP vesicles leads to chelation of the calcium ions and to a transition to multilamellar vesicles.
Synthesis of carba‐β‐DL‐fucose and carba‐β‐DL‐galactose from myo‐inositol
Authors: Verduyn R. , van Leeuwen S. H. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractCyclic ketone 12, prepared from racemic 3‐O‐benzyl‐1,2:4,5‐di‐O‐cyclohexylidene‐myo‐inositol (4), was converted into the tertiary alcohols 13 and 20 by treatment with methyl‐magnesium bromide and (benzyloxymethyl)lithium, respectively. Deoxygenation, followed by hydrogenolysis of the benzyl protective groups, furnished the title compounds 2 and 3.
Synthesis and properties of a fluorescent nucleotide derivative
Authors: Petra D. G. I. , de Boer R. F. , Koomen G. J. , Meeuwenoord N. J. , Kuyl‐Yeheskiely E. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractStrong fluorescent deoxyadenosine derivatives are of considerable research importance in cell biology. We prepared the deoxyriboside of methyl 3,7‐dihydro‐7‐oxo‐[2,1‐i]pyrimidopurine‐9‐carboxylate (compound 1b, deoxyribofuranosyl A*)1 which was subsequently used in the synthesis of the dimer d(A*T).
New bioactive organic compounds from turkish medicinal plants
Authors: ŞLener Bilge , Atta‐Ur‐Rahman Atta‐Ur‐Rahman 
Published: September 2010

AbstractTurkey has a very rich flora and a long history of herbal medicine practices. The biological evaluation of substances from plant sources is highly relevant for the identification of lead compounds which can result in the development of novel and safe medicinal agents. During our extensive studies with Turkish medicinal plants, we have isolated and characterized a large number of natural products. Although Turkey is endowed with a wide variety of medicinal plants, very little effort has been made so far towards bioassay‐directed isolation of biologically active compounds from indigenous plants. During the past few years, we have also been engaged in the isolation and structure elucidation of compounds through a bioassay‐directed fractionation procedure.In this manuscript, new bioactive steroidal alkaloids isolated from Buxus, Veratrum and Fritillaria species are presented. Among these, four steroidal alkaloids isolated from the leaves of Buxus longifolia have shown significant antibacterial activity against Salmonella typhi, Shigella flexneri, Escherichia coli and Pseudomonas aeruginosa. Three steroidal alkaloids from Veratrum album have been shown to have antihypertensive actions. In addition, a new steroidal base obtained from the bulbs of Fritillaria imperialis exhibited anticholinergic activity as manifested by the blockade of acetylcholine responses on isolated guinea‐pig ileum and atria.
Virtually no environmental impact: The biphasic oxo process
Authors: Cornils Boy , Wiebus Ernst 
Published: September 2010

AbstractWater‐soluble catalysts offer significant advances in homogeneous catalysis: the “heterogenization” of the catalyst in a second, immiscible liquid phase immobilises the catalyst phase, thus combining the advantages of heterogeneous catalysis, e.g. long lifetime, easy separation of product from catalyst, with those of the homogeneous type, namely, defined species of catalyst, gentle reaction conditions, high activity and selectivity.The first successful large‐scale application of aqueous catalysts is the oxo process of Ruhrchemie/Rhône‐Poulenc, using a HRh(CO)[P‐(3‐sulfophenyl‐Na)3]3 catalyst, dissolved in water. This survey reviews 10 years' experience of this process against the background of biphasic catalyses, especially the way in which this environmental benign technique, which is highly economic and thus very environmentally sound, reduces pollution.
Oxidation of glucose and gluconate on Pt, Pt Bi, and Pt Au catalysts
Authors: Besson M. , Flèche G. , Fuertes P. , Gallezot P. , Lahmer F. 
Published: September 2010

AbstractGlucose and gluconate aqueous solutions (2 mol/l) were oxidized with air (atmospheric pressure, 333K, pH 7) on active charcoal‐supported, platinum catalysts (catalytic ratios substrate/Pt ≥ 787); some catalysts were promoted with bismuth or gold. The activity of unpromoted Pt/C catalysts for glucose oxidation was comparable with that of Pd‐Bi/C catalysts and there was no deactivation; gluconate formed transiently was oxidized into glucarate, the final selectivity did not exceed 50%. The oxidation of gluconate on very well dispersed Pt catalysts prepared by cationic exchange or anionic adsorption leads to higher glucarate selectivities than those previously reported, in spite of the fact that the present solutions were much more concentrated and reduced amounts of platinum were used. Addition of bismuth adatoms by surface redox reaction produces a shift in selectivity towards 2‐ketogluconate. Addition of gold adatoms on platinum decreases the catalyst deactivation.
Catalyzed oxidation of 2‐mercaptobenzothiazole to 2‐hydroxybenzothiazole
Authors: Stolcova Magdalena , Hronec Milan 
Published: September 2010

AbstractThe selective oxidation of 2‐mercaptobenzothiazole to 2‐hydroxybenzothiazole with molecular oxygen at temperatures of 50‐150°C and pressures of 0.3‐0.7 MPa has been studied in the presence of transition metal catalysts. The reaction proceeds via corresponding sulfinic and sulfonic acids which are quickly decomposed to the desired product in acetic acid as solvent at the reaction temperature. At temperatures below 90°C, the main reaction product is 2,2′‐dithiobis(benzothiazole) which is resistant to further oxidation. The type of central atom and ligand of the metal catalyst has a strong influence on the selectivity of 2‐hydroxybenzothiazole formation. In the presence of FeCl2 as catalyst, 85% selectivity at 95% conversion was achieved.
Environmentally friendly synthesis of coumarin derivatives employing heterogeneous catalysis
Authors: Gunnewegh E.A. , Hoefnagel A.J. , Downing R.S. , van Bekkum H. 
Published: September 2010

AbstractZeolite H‐BEA and other solid acids have been shown to be effective catalysts for the production of coumarin derivatives from activated phenols and acids or esters possessing an additional alkylation function, or β‐keto esters (Pechmann reaction). These heterogeneous catalysts eliminate the production of acidic waste streams associated with conventional (Lewis) acid catalysts. Zeolite H‐BEA proved to be the preferred catalyst.
Alcohol‐dehydrogenase‐catalyzed production of chiral hydrophobic alcohols. A new approach leading to a nearly waste‐free process
Authors: Kruse Wolfgang , Hummel Werner , Kragl Udo 
Published: September 2010

AbstractThe enantioselective enzyme‐catalyzed reduction of ketones in an enzyme membrane reactor coupled to a membrane‐based extractive product separation was developed for the production of chiral hydrophobic alcohols. Enantiomerically pure (S)‐1‐phenylpropan‐2‐ol, (S)‐4‐phenylbutan‐2‐ol and (S)‐6‐methylhept‐5‐en‐2‐ol (sulcatol) were obtained with high purities.In spite of low substrate concentrations (9‐12 mM) space‐time yields higher than 100 g/(l·d) and concentrated product solutions were obtained.Formate‐dehydrogenase‐catalyzed regeneration of cofactor, together with process‐integrated recycling of cofactor, led to total‐turnover numbers for NAD+ of up to 1350 molP/molNAD, which means a 25‐fold increase in comparison with standard techniques without cofactor retention.Because of the closed‐loop design of the reactor the process can be run almost without waste, yielding the pure chiral alcohol and CO2.
Alternating copolymerization of alkenes and carbon monoxide catalyzed by cationic palladium complexes
Authors: Drent E. , van Broekhoven J.A.M. , Budzelaar P.H.M. 
Published: September 2010

AbstractIn the late 1940s,Reppediscovered a nickel catalyst for the co‐oligomerization of ethene and carbon monoxide. Since then, various groups have made attempts to develop more efficient catalysts for this reaction. The recent discovery of a new class of very active palladium catalysts now allows, for the first time, ready access to a large variety of high‐molecular‐weight alkene/carbon‐monoxide co‐ and terpolymers. The catalysts comprise acis‐coordinated palladium(II) species associated with weakly or non‐coordinating anions. Their discovery has made it possible to develop a viable process for the commercial production of the first members of the new family of CARILON‐olefin/carbon monoxide copolymers.In this brief review, we highlight some key phenomena in polyketone catalysis. The elementary reaction steps in the palladium‐catalyzed polyketone formation during chain propagation, initiation and termination are outlined. The role of bidentate ligands and the reasons for perfect alternation in polymer chain growth are dicussed. The attractive feature of the catalysts, that they also catalyze the co‐ and terpolymerization of olefins higher than ethene with carbon monoxide, is briefly noted. A parallel between polyketone catalysis by cationic palladium complexes and modern polyolefin catalysis by cationic metallocene complexes is suggested.
Unprecedented observation of pronounced vibrational structure in charge‐transfer absorption and emission spectra
Authors: Wiering P.G. , Verhoeven J.W. 
Published: September 2010

AbstractTwo rigidly bridged electron donor‐acceptor systems are reported that display discrete, intramolecular charge‐transfer (CT) absorption and emission spectra in solution at room temperature. For both the CT‐absorption is highly structured irrespective of solvent, for one also the CT‐fluorescence in a nonpolar solvent is structured.
Synthesis and spectroscopic characterisation of 13C‐labelled anthranilic acid
Authors: van Liemt W.B.S. , van Henegouwen W. G. Beijersbergen , van Rijn A. , Lugtenburg J. 
Published: September 2010

AbstractThe three isotopomers (1–13C)‐, (2‐13C)‐, and (6‐13C)‐ anthranilic acid (2‐aminobenzoic acid) have been synthesised from simple 99% 13C‐labelled starting materials. The isotopomers have been characterised using mass spectrometry, 1H‐NMR spectroscopy and 13C‐NMR spectroscopy. The spectroscopic results confirm that, within experimental error, the syntheses were accomplished without scrambling or dilution of label. The labelled anthranilic acids are used as substrates for bioconversion into the correspondingly labelled L‐tryptophans. For this purpose, the (2‐13C)‐ label has been synthesised on the gram scale.
An efficient synthetic method for β‐cyclolavandulal and its corresponding alcohol
Authors: Oda Mitsunori , Isobe Atsushi , Hayashi Masashi , Miyatake Ryuta , Shimao Ichiro , Kuroda Shigeyasu 
Published: September 2010

Abstract3,3‐Dimethylcyclohexanone (5) was efficiently converted to methyl β‐cyclolavandulate (6) in 74% yield in three steps, one of which included the preparation of β‐methyl α,β‐unsaturated esters by coupling lithium dimethylcuprate with enol phosphates of β‐oxo esters. Reduction of 6 with LiAlH4 gave β‐cyclolavandulol (2) in 94% yield and oxidation of 2 with pyridinium chlorochromate in the presence of molecular sieves afforded the title aldehyde quantitatively.
Synthesis of alkyl ethynyl tellurides and 1,2‐bis(alkyltelluro) acetylenes by electrophilic‐reagent‐induced reaction of dialkyl ditellurides with acetylene
Authors: Potapov V.A. , Amosova S.V. , Shestakova V.Y.U. , Zhnikin A.R. , Petrov B.V. 
Published: September 2010

AbstractThe reaction of dialkyl ditellurides with acetylene occurs only in the presence of an electrophilic reagent (alkyl halides, Lewis acid) to afford alkyl ethynyl tellurides and 1,2‐bis(alkyltelluro) acetylenes in up to 96% total yield.
A thermal rearrangement of ethylene acetal of bicyclo[4.2.0]octa‐4,7‐diene‐2,3‐dione
Authors: Oda Mitsunori , Kamata Yoshitaka , Nishii Satoshi , Miyatake Ryuta , Kuroda Shigeyasu , Oda Masaji 
Published: September 2010

AbstractPyrolysis of the title compound 3 at 400 °C gave α‐(2‐hydroxyphenyl)‐γ‐butyrolactone (4) whose structure was confirmed by an alternative synthesis. A reaction mechanism via a phenyl ketene acetal is proposed.
Surface reactions of ethylene with deuterium, oxygen and nitrogen oxide on rhodium: Kinetics and mechanism
Authors: Niemantsverdriet J.W. , Borg H.J. , van Hardeveld R.M. , van Santen R.A. 
Published: September 2010

AbstractThe kinetics of surface reactions of ethylene adsorbed on the (111) surface of a rhodium single crystal has been investigated by means of temperature‐programmed desorption and static secondary‐ion mass spectrometry (SSIMS). These reactions include the decomposition of ethylene to ethylidyne (CCH3), and the exchange of H for D‐atoms in the latter, the oxidation of adsorbed ethylene and its reaction with coadsorbed NO. The formation of relatively large amounts of HCN indicates that C‐N coupling on rhodium is possible under mild conditions.
Mechanistic study of the selective hydrogenolysis of CCI2F2 (CFC‐12) into CH2F2 (HFC‐32) over palladium on activated carbon
Authors: van de Sandt Emile J. A. X. , van Bekkum Herman , Wiersma André , Makkee Michiel , Moulijn Jacob A. 
Published: September 2010

AbstractThe influence of process parameters such as temperature (400‐560K), H2/CCl2F2 ratio (2.2‐20), and Weight Hourly Space Velocity (WHSV) (0.3‐1.0 g/(g · h)) on the hydrogenolysis of CCl2F2 into CH2F2 over palladium on activated carbon has been investigated. The reactivity of CHCIF2 and CH2F2 and the influence of HCl were also examined. In the reaction of CCl2F2, the main product is CH2F2. Significant amounts of CHCIF2 and CH4 are also found. The catalyst shows a remarkably high selectivity to CH2F2, in the range of 70‐90 mol%, at all conversion levels in a broad range of process conditions. A mechanism is proposed in which the reaction proceeds mainly via parallel reaction pathways. One route results in CH2F2 and CHCIF2, while the other route yields CH4. The selectivity to CH2F2 and CHCIF2 is determined by the amount of adsorbed chlorine on the catalytic surface and a constant selectivity for CH4 was found. High selectivity for CH2F2 can be achieved at high H2/CCl2F2 ratios and low HCl concentration. The postulated mechanism is supported by thermodynamic data.