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41.
Robert A. Egli und Susanne Tanner 《Fresenius' Journal of Analytical Chemistry》1979,295(5):398-401
Zusammenfassung Mit 2 sauren, 2 basischen und einem neutralen Fließmittel mit unterschiedlichen Polaritäten und guten Trennleistungen konnten 151 von 157 geprüften Arzneisubstanzen mit hRf-Werten zwischen 10 und 90 chromatographiert werden.
Universal halogen-free TLC solvent systems for drug substances
Summary Using two acidic, two alkaline and a neutral mobile phase of different polarities and high separation efficiencies 151 of 157 tested drug substances could be chromatographed with hRf-values between 10 and 90.相似文献
42.
Robert A. Egli 《Helvetica chimica acta》1970,53(1):47-53
The reduction of benzonitrile with sodium borohydride in aqueous methanol in the presence of Raney nickel as a catalyst provides high yields of benzylamine as compared with the known low yields in the absence of Raney nickel. An explanation is proposed. Butyronitrile gives similar good yields of n-butylamine. 相似文献
43.
Robert A. Egli 《Helvetica chimica acta》1968,51(8):2090-2097
Sodium tetrahydroborate has a poor reduction capacity for the elimination of aromatic halogens. The addition of metal catalysts (in particular Pd, Co, Ni, Cu) accelerates this reaction to such an extent that even the rather stable aromatic chlorine can be exchanged by hydrogen at room temperature. An activity order of catalysts (the best is palladium on charcoal), a reactivity comparison of iodine, bromine and chlorine, and the influence of ortho, meta or para position in halogenobenzoic acids in relation to halogenobenzenes and to several other halogen compounds are given. Two preparative examples are described. 相似文献
44.
45.
J. P. Marion F. Müggler-Chavan R. Viani J. Bricout D. Reymond R. H. Egli 《Helvetica chimica acta》1967,50(6):1509-1516
A gas-chromatographic separation of cocoa aroma, followed by infra-red and mass-spectrometric identification, has yielded, besides 22 of the 91 previously described constituents, 35 new substances (8 aliphatic, 1 alicyclic, 7 aromatic, 9 o-heterocyclic, 4 pyrrolic, and 6 pyrazinic). 相似文献
46.
F. Kieffer und R. H. Egli 《Fresenius' Journal of Analytical Chemistry》1966,221(1):416-424
Zusammenfassung Es wird eine universell anwendbare Methode zur Analyse der in Lebensmitteln vorkommenden Nucleotide beschrieben. Die Trennung erfolgt durch Ionenaustauschchromatographie in einer teilweise automatisierten Apparatur unter standardisierten Bedingungen und dauert nur etwa 5 Std. Es werden sämtliche für die Identifizierung und die quantitative Berechnung benötigten optischen Konstanten, sowie die relativen Migrationsgeschwindigkeiten in der Papierelektrophorese, angegeben. Auf spezielle Methoden zur Strukturanalyse der Nucleotide wird hingewiesen.
Verwendete Abkürzungen NAD=DPN Nicotinamid-Adenin-Dinucleotid - CMP Cytidylsäure - AMP Adenylsäure - UMP Uridylsäure - IMP Inosinsäure - GMP Guanylsäure, -DP und -TP sind Di- bzw. Triphosphate - dTMP Desoxythymidylsäure 相似文献
Summary An universal method for the analysis of nucleotides in foods is described. The nucleotides are separated by ion-exchange chromatography in a partly automatic apparatus under standardized conditions. This is achieved in less than five hours. Optical constants for the identification and quantitative determination are recorded. The relative migration velocity in paper electrophoresis is also listed. References are made to special methods for closer investigation of the nucleotide structure.
Verwendete Abkürzungen NAD=DPN Nicotinamid-Adenin-Dinucleotid - CMP Cytidylsäure - AMP Adenylsäure - UMP Uridylsäure - IMP Inosinsäure - GMP Guanylsäure, -DP und -TP sind Di- bzw. Triphosphate - dTMP Desoxythymidylsäure 相似文献
47.
48.
Wilds CJ Wawrzak Z Krishnamurthy R Eschenmoser A Egli M 《Journal of the American Chemical Society》2002,124(46):13716-13721
(L)-alpha-Threofuranosyl-(3'-->2')-oligonucleotides (TNA) containing vicinally connected phosphodiester linkages undergo informational base pairing in an antiparallel strand orientation and are capable of cross-pairing with RNA and DNA. TNA is derived from a sugar containing only four carbon atoms and is one of the simplest potentially natural nucleic acid alternatives investigated thus far in the context of a chemical etiology of nucleic acid structure. Compared to DNA and RNA that contain six covalent bonds per repeating nucleotide unit, TNA contains only five. We have determined the atomic-resolution crystal structure of the B-form DNA duplex [d(CGCGAA)Td(TCGCG)](2) containing a single (L)-alpha-threofuranosyl thymine (T) per strand. In the modified duplex base stacking interactions are practically unchanged relative to the reference DNA structure. The orientations of the backbone at the TNA incorporation sites are slightly altered in order to accommodate fewer atoms and covalent bonds. The conformation of the threose is C4'-exo with the 2'- and 3'-substituents assuming quasi-diaxial orientation. 相似文献
49.
50.
Martina Schulze‐Adams Bruno Bernet David Touboul Daniel Egli Lorenz Herdeis Andrea Vasella 《Helvetica chimica acta》2014,97(9):1244-1268
The G[s ]G dinucleoside 6 and the G[s ]G* dinucleoside 8 were prepared by alkylation of the guanosine thiols derived from 2 and 5 , respectively, by the C(8)‐chloromethylated guanosine 4 that was obtained from alcohol 3 . Dinucleosides 6 and 8 were deacylated to 7 and 9 , and fully deprotected to 10 and 11 , respectively. The G[n ]G dinucleoside 16 was obtained by reductive amination of aldehyde 13 with an iminophosphorane derived from azide 14 and deprotection of the resulting dimer 15 . In the solid state of 6 , and in a solution of 6 and 8 in CDCl3, H? N(1/I) and H? N(1/II) are engaged in intramolecular H‐bonds to the C?O of the isobutyryl protecting groups, and HN of the isobutyryl group of unit I forms an interresidue, intramolecular H‐bond to N(7/II), leading to a syn orientation of the nucleobase at unit I, to a tg orientation of the sulfanyl moiety, and to an orthogonal orientation of the nucleobases, preventing any base pairing. The silylated and isopropylidenated dinucleosides 7 and 9 are present in DMSO solution as solvated monoplexes. Broad 1H‐NMR signals of the nucleosides 7 and 16 in CHCl3 solution evidence equilibrating G‐quadruplexes. The quadruplex formation of 7 and 16 was established by 1H‐NMR spectroscopy (only of 16 ), vapour pressure osmometry, mass spectrometry, and CD spectroscopy. The C(6(I))‐hydroxymethylated analogue 9 in CDCl3 and the fully deprotected dinucleosides 10 and 11 in H2O form only weakly π? π stacked associates, but no G‐quadruplexes, as evidenced by CD spectroscopy. 相似文献