Ringerweiterungen an Benzochinol-acetaten, 2. Mitt.: Synthese von Troponen aus Benzochinolacetaten; β-Alkylierung des o-Acetoxy-cyclohexadienonsystems; Herstellung von 2-Aminotroponen

Zusammenfassung Ausgehend von Phenolen bestimmter Konstitution kann man mit Hilfe der o-Benzochinol-acetate durch Ringerweiterung mit Diazomethan—Bortrifluorid zu Troponen mit derselben Substituentenfolge gelangen¹. Als Nebenprodukte treten die in Stellung 5 methylierten Chinolacetate und Tropone auf. Durch Variation der Substituenten in Stellung 1 und 5 des o-Cyclohexadienon-systems ist es möglich, die Ringerweiterung oder die Methylierung in Position 5 zur Hauptreaktion zu machen.Einwirkung von Hydrazinhydrat auf das Tropon liefert ein Gemisch aus 2-Amino- und 2-Hydrazinotropon. Hydrogenolyse der Hydrazinoverbindung mitRaney-Nickel gibt in guter Ausbeute die Aminoverbindung.Mit 1 Abbildung1. Mitt.:E. Zbiral, J. Jaz undF. Wessely, Mh. Chem.92, 1155 (1961).     

Hjelmslev-Ebenen mit verfeinerten Nachbarschaftsrelationen

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The Magnus property for direct products

A group G is said to have the Magnus property if the following holds: whenever two elements x, y have the same normal closure, then x is conjugate to y or to y^?1. We prove: let p be an odd prime, and let G, H be residually finite-p groups with the Magnus property. Then the direct product \({G \times H}\) has the Magnus property. By considering suitable crystallographic groups, we give an explicit example of finitely generated, torsion-free, residually finite groups G, H with the Magnus property such that the direct product \({G \times H}\) does not have the Magnus property.     

Cobaltocenium Carboxylate Transition Metal Complexes: Synthesis,Structure, Reactivity,and Cytotoxicity

Cobaltocenium carboxylate is an unusual betaine that functions as a formally neutral carboxylate ligand with late transition metal centers comprising Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Rh⁺. Structurally, a rich coordination chemistry is observed – from simple monomeric homoleptic complexes to heteroleptic dimeric, trimeric, and polymeric compounds, as shown by X‐ray diffraction of 11 compounds. Chemically, thermal decarboxylation was investigated aiming at the formation of cobaltocenium‐carbene transition metal complexes, in analogy to such chemistry of imidazolium carboxylate betaines. Cytotoxicity studies of cobaltocenium carboxylate transition metal complexes were performed to evaluate the medicinal bioorganometallic potential of these compounds. While cobaltocenium carboxylate was inactive, its complexes with Ag⁺, Cd²⁺, and Hg²⁺ triggered significant cytotoxic effects.     

Eigenmodes in the long-time behavior of a coupled spin system measured with nuclear magnetic resonance

The many-body quantum dynamics of dipolar coupled nuclear spins I=1/2 on an otherwise isolated cubic lattice are studied with nuclear magnetic resonance. By increasing the signal-to-noise ratio by 2 orders of magnitude compared with previous reports for the free induction decay (FID) of (19)F in CaF(2) we obtain new insight into its long-time behavior. We confirm that the tail of the FID is an exponentially decaying cosine, but our measurements reveal a second decay mode with comparable frequency but twice the decay constant. This result is in agreement with a recent theoretical prediction for the FID in terms of eigenvalues for the time evolution of chaotic many-body quantum systems.     

Neutral particle focusing in composite driven dissipative billiards

Dynamical focusing of ensembles of neutral particles in energy and configuration space has been demonstrated recently (Petri et al. in Phys. Rev. E (R) 82:035204, 2010) using time-dependent elliptical billiards. The interplay of nonlinearity, dissipation, and driving yields the occurrence of attractors in the phase space of the billiard. Here, we show that dissipative oval billiards with slowly oscillating elliptical scatterers in the interior allow for a dynamical focusing on simple periodic trajectories with close to perfect efficiency. This setup should be more amenable to corresponding experiments of certain type which are briefly discussed.     

Extremal entropy for a constrained probability density

The state of extremal entropy for a one-dimensional probability density is considered. This density is constrained by fixed values of the first and second moment. The grandcanonical distribution yields the extremum of the entropy within a certain range of values of the moments. A different type of density corresponds to an extremum of entropy when the moments are outside this range. The shape of this density is approximated with the Ritz variation method. The results are applied to the formation of breathers in the discrete nonlinear Schrödinger equation.     

Extrempunkte und Minimumsätze bei Hüllenbildungen

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Eine neuartige Synthese von substituierten m-Hydroxybenzaldehyden

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