Showing papers by "Ulrike Holzgrabe published in 1994"
TL;DR: In this paper, the resolution of nine sympathomimetic phenethylamine racemates by beta-cyclodextrin and heptakis(2,3-di-O-acetyl)beta-cyclodesxtrin has been investigated by capillary electrophoresis and 1H NMR spectroscopy.
53 citations
TL;DR: It is concluded that one half of the lead compound is pivotal for an interaction with the allosteric site of the M2-cholinoceptor, whereas the opposite end of the molecule modulates theAllosteric activity.
Abstract: The bis(dichlorobenzyl) ether of the bispyridinium oxime TMB 4 stabilizes antagonist binding to M2-cholinoceptors which is indicative of an allosteric action. More than 10 derivatives of the lead compound were synthesized to investigate structure-activity relationships. The allosteric potency of the compounds was indicated by the concentrations which retarded the rate of dissociation of [3H]N-methylscopolamine from porcine cardiac cholinoceptors by a factor of 2 (EC50). Compared with TMB 4, the bis(dichlorobenzyl) derivative 4a displayed a more than 200-fold higher potency (EC50 = 4.7 microM). One of the dichlorobenzyl groups could be replaced by a methyl group without loss of activity (EC50 = 4.5 microM). Further shortening of this end of the molecule was accompanied by a moderate decline in potency to a minimum of EC50 = 26 microM. The second quaternary nitrogen was not a prerequisite for an allosteric activity. It is concluded that one half of the lead compound is pivotal for an interaction with the allosteric site of the M2-cholinoceptor, whereas the opposite end of the molecule modulates the allosteric activity.
39 citations
TL;DR: Analyses of 1 H and 13 C NM R spectra of 1 5 gyrase inhibitors were carried out using mainly the hydrogen-fluorine and the carbon-fluoric coupling constants.
Abstract: Analyses of 1 H and 13 C NM R spectra of 1 5 gyrase inhibitors were carried out using mainly the hydrogen-fluorine and the carbon-fluorine coupling constants. 19 F NMR chemical shifts were obtained for pefloxacin and its metabolites
22 citations
TL;DR: The structure-activity relationships found with this series of agents did not parallel findings made previously with similarly modified derivatives of the bispyridinium compound DUO 3, (E,E)-1,1′- (1,3-propanediyl)-bis[4-[[(2,6-dichlorobenzoxyl)imino]-methyl]pyrid inium] dibromide, despite considerable similarity with respect to molecular shape and charge distribution
22 citations
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TL;DR: In this article, the authors describe the Oxidation of ω-Phenylalkylmalonate derivatives, which can afford cyclization products as well as nitro-, alcohol and acetoxy compounds.
Abstract: Die Oxidation der ω-Phenylalkylmalonsaurederivate 1a-f fuhrt nicht nur zu Cyclisierungsprodukten 2, sondern auch zu offenkettigen Nitro-, Alkohol- und Acetoxyderivaten 3–7. Es wird eine empfindliche Abhangigkeit der Produktverteilung von Reaktionstemp. und Wassergehalt des Reaktionsmediums sowie der Natur der Carbonylgruppen beobachtet. Das wahrend der Reaktion entstehende Ce3+-Ion ist fur die Entstehung offenkettiger Nebenprodukte verantwortlich.
Cerium(IV) Oxidations, X: Oxidation of ω-Phenylalkyldicarbonyl- and Dicarbonyl-analogous Derivatives
Oxidations of the ω-phenylalkylmalonate derivatives 1a-f afford cyclization products 2 as well as nitro-, alcohol and acetoxy compounds 3–7. The distribution of products depends sensitively on the temp, and on the water content of the reaction medium and as well on the chemical nature of the carbonyl functions. Ce3+-ion formed during the reaction is responsible for the observed ring-opened side products.
3 citations
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