Die Methanolyseprodukte von 14-Brom-codeinon-dimethylacetal: (14S)-14-Methoxy-codeinon

Zusammenfassung Beim Erhitzen von 14-Brom-codeinon-dimethylacetal (1) in absol. Methanol mit einer äquivalenten Menge Na₂CO₃ entstehen die drei isomeren Methoxycodeinon-acetale3, 4 und5 sowie die beiden Indolino-codeinonderivate6 und7. Die Strukturen und Konfigurationen der Verbindungen3–6 werden auf Grund der NMR- und IR-Spektren sowie durch Umwandlung in bekannte Verbindungen bewiesen.

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The methanolysis of 14-bromo-codeinone dimethyl acetal

14-Bromocodeinone dimethyl acetal (1) reacts in methanol containing sodium carbonate (0.5 moles) to give the three isomeric methoxycodeinone acetals3, 4, and5 besides the indolino-codeinones6 and7. The structures and configurations of3–6 were established on the basis of NMR- and IR-spectroscopy and by conversion to known compounds.

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Herrn Prof.E. Ziegler mit den besten Wünschen zum 60. Geburtstag gewidmet.     

Ir-catalyzed C-H activation in the synthesis of borylated ferrocenes and half sandwich compounds

The complex generated from 1/2[Ir(OMe)(cod)]2 and 4,4'-di-tert-butyl-2,2'-bipyridine catalyzes the regioselective borylation of ferrocenes, CpMn(CO)3 and CpMo(CO)3CH3 with a stoichiometric amount of B2pin2.     

Determination of low-molecular-mass quaternary ammonium compounds by capillary electrophoresis and hyphenation with mass spectrometry

The determination of quaternary ammonium ions by capillary electrophoresis (CE) is reviewed. The analytes include tetraalkylammonium and alkylbenzyldimethylammonium compounds frequently used as antiseptic and antibacterial agents as well as in various household products, several plant growth regulators and herbicides, by-products in bile acid sequestrants, and a range of anticholinergic drugs. Besides direct and indirect UV detection, hyphenation with electrospray mass spectrometry is particularly suited for quaternary ammonium ions and may lower the detection limits by two orders of magnitude. In comparison with established liquid chromatographic techniques, CE may exhibits superior separation efficiency. Applications in routine analysis have demonstrated that CE is reliable and robust enough to represent a real alternative to chromatography.     

Configuration and E/Z interconversion mechanism of O(S)-allyl-S(O)-methyl-N-(acridin-9-yl) iminothiocarbonate

The configuration and dynamic behavior of O-allyl-S-methyl-N-(acridin-9-yl)iminothiocarbonate (1) and its S-allyl-O-methyl regioisomer (2) were studied using quantum chemical calculations and by applying a novel graphical method to scatter maps obtained from MD simulations for evaluation of an NOE-weighted internuclear distance (r(NOE)). Energy calculations indicated that the Z configuration was predominant for each compound and, further, this was supported both by the calculated chemical shifts and the r(NOE). Both N-inversion- and rotation-type transition-state structures were also calculated for the E/Z isomerization process, the results indicating that the preferred interconversion mechanism for 1 is N-inversion, but contrastingly, interconversion via rotation is equally as probable as N-inversion for 2. This supports the notion that one or the other or both pathways can be active and each system needs to be assessed on a case-by-case basis.     

A photochemical route for efficient cyclopeptide formation with a minimum of protection and activation chemistry

An elaborated protocol is described which allows the efficient transformation of di-, tri-, and tetrapeptides into cyclopeptides with a minimum of protection and activation chemistry using the photoinduced electron transfer initiated decarboxylation of N-phthaloyl peptides resulting in C-C coupling between the initially formed carbon radicals.     

Neue Sulfonamide, 12. Mitt. 5-Halogen-substituierte Sulfanilamido-methoxy-pyrimidine

Zusammenfassung Es wird die Darstellung von 2-Sulfanilamido-4-methoxy-5-chlorpyrimidin, 2-Sulfanilamido-4-methoxy-5-jodpyrimidin sowie 4-Sulfanilamido-2-methoxy-5-chlorpyrimidin beschrieben. Die erste Verbindung wurde auf zwei voneinander unabhängigen Synthesewegen erhalten. W. Klötzer undJ. Schantl, Mh. chem.94, 1178 (1963).     

Using the diphosphanyl radical as a potential spin label: effect of motion on the EPR spectrum of an R1(R2)P--PR1 radical

The EPR spectrum of the novel radical Mes*(CH3)P--PMes* (Mes*=2,4,6-(tBu)3C6H2) was measured in the temperature range 100-300 K, and was found to be drastically temperature dependent as a result of the large anisotropy of the 31P hyperfine tensors. Below 180 K, a spectrum of the liquid solution is accurately simulated by calculating the spectral modifications due to slow tumbling of the radical. To achieve this simulation, an algorithm was developed by extending the well-known nitroxide slow-motion simulation technique for the coupling of one electron spin to two nuclear spins. An additional dynamic process responsible for the observed line broadening was found to occur between 180 K and room temperature; this broadening is consistent with an exchange between two conformations. The differences between the isotropic 31P couplings associated with the two conformers are shown to be probably due to an internal rotation about the P--P bond.     

Expansions for von Mises functionals

Summary Berry-Esseen results and expansions are derived for the distribution function of von Mises functionals of order r under moment conditions and conditions on the smoothness of the limit distribution.The results apply to goodness-of-fit statistics — as well as to the central limit theorem in L ^2p,p2, the rate of convergence being O(n ^–1) for centered balls, provided a fourth moment exists.Research sponsored in part under Office of Naval Research. Contract Number N00014-80-C-0163.     

Analysis of lipoproteins with analytical capillary isotachophoresis

An analytical free flow capillary isotachophoresis procedure, with a discontinuous electrolyte system, for the detailed analysis of lipoproteins in human body fluids has been developed. The technique is based on prestaining whole serum lipoproteins with a lipophilic dye before separation. Human serum lipoproteins are separated into 14 well-characterized subfractions according to their electrophoretic mobility. High density lipoproteins (fraction 1 to 6) are separated into three major subpopulations, the fast migrating high density lipoprotein (HDL) subpopulation, containing mainly apo AI and phosphatidylcholine, the subpopulation with intermediate mobility, consisting of particles rich in apo AII, apo E, and C apolipoproteins, and the slowly migrating HDL subfraction, containing mainly particles rich in apo AI, apo AIV, and lecithin: cholesterol acyltransferase (LCAT) activity. The apo B containing lipoproteins (fraction 7 to 14) can be subdivided into four major functional groups. The first represents chylomicron derived particles and large triglyceride-rich very low density lipoproteins (VLDL). The second group consists of small VLDL and intermediate density lipoprotein (IDL) particles, anf the third and fourth group represent the low density lipoproteins. The isotachophoretic analysis of human serum samples obtained from patients with hyperlipoproteinemias is compatible with the classification according to the Frederickson phenotypes and reflects the respective biochemical abnormalities. Furthermore, several genetic disorders of lipid and lipoprotein metabolism like HDL deficiency syndromes, familial LCAT deficiency, Fish eye disease, hypobetalipoproteinemia and abetalipoproteinemia can be well characterized by analytical capillary iso tachophoresis. In addition to patient analysis we investigated the influence of lipid lowering drugs on the lipoprotein subfraction distribution during therapy with analytical capillary isotachophoresis.     

An improved method for assay of vitamin C in fish feed and tissues

Summary A method was devised to assay four forms of vitamin C: L-ascorbic acid (AA), dehydroascorbic acid (DHA), ascorbate-2-mono- and polyphosphate (AMP, APP), as well as ascorbate-2-monosulphate (AMS), in sample series of different fish tissues and feed. Direct and indirect detection were combined. Sample extractions were carried out with 0.2 mol L⁻¹ sodium acetate buffer (pH 4.8) and extracts were deproteinized after different chemical or enzymatic reactions, with perchloric acid. The DHA was reduced to AA with dithioerythritol (DTE). Ascorbate oxidase enzyme was used for the detection of background and an acidic phosphatase enzyme for the hydrolysis of different phosphate esters. Ascorbate-2-sulphate was detected directly with help of coinjection of the compound. Chromatographic analysis was carried out with a single column isocratic reverse phase method. The mobile phase was an aqueous buffer of 0.04 M sodium-acetate, 0.05 mM EDTA, 0.5 mM tetrabutylammonium dihydrogen phosphate (TBA) adjusted to pH 3.76 with 85% H₃PO₄ and with 24 mL methanol added to 1000 mL. C-18 columns were used with 0.6 mL min⁻¹ flow rate at 23°C. The vitamin C forms were detected by UV absorption at 250 nm. The determination limit was 1.0–5.0 μg g⁻¹ in AA equivalent. The standard deviations were between 1–6% and depended on the concentrations of vitamin C forms and tissues. Recoveries were between 90–96% in samples. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997