Resolution of four k-region arene imines and mutagenicity of the optically pure aziridines

Racemic K-region imines of benz[a]anthracene, 7-methylbenz[a]anthracene, chrysene and benzo[a]pyrene ( 1–4 , respectively) have been resolved by high performance liquid chromatography on a column packed with amylose tris(3,5-dimethylphenylcarbamate) on silica gel. The absolute configuration of the resolved aziridines was assigned by comparison of their circular dichromism spectra to those of the corresponding enantiomerically pure arene oxides. The mutagenicity of the enantiomers of the arene imines was investigated using Salmonella typhimurium strains TA98 and TA100. Although all arene imines investigated were potent mutagens, quantitative and qualitative differences in the mutagenic activity were observed between enantiomers.     

Etude sur les composés organométalliques. XVIII. Synthèse et caractérisation du μ-oxo-bis (dicyclopentadiènylméthyltitane IV)

Studies of Organometallic Compounds. XVII: Synthesis and Caracterisation of μ-oxo-bis(dicyclopentadienylmethyltitane IV) (Cp₂TiCH₃)₂O is obtained by reacting (Cp₂TiCl)₂O with methyllithium. IR., NMR. and MS. spectrum are reported. Autocatalytic decomposition of the product is inferred from differential thermal analytic measurements.     

Untersuchung von Harn, Blut und sonstigem biologischen Material

Ohne Zusammenfassung     

Structures and Mutagenic Properties of Products Obtained by C-Nitrosation of Opipramol

Reaction of the tricyclic psychotropic drug opipramol ( 1 ) with an excess of HNO₂ affords a product mixture mutagenic for Salmonella typhimurium. The main product is a tetracyclic furoxan 2 (yield ca. 80%), resulting from nitrosation at C(10) and C(11) of 1 . Compound 2 is not mutagenic. The essential mutagen is a nitroarene 3 formed via contraction of the central ring of 1 , and nitrosation at C(2). Its yield is extremely low (<0.1%). Nitroarenes have previously not been encountered as mutagenic products of the interaction of drugs with nitrite.     

Substituenteneffekte auf die NMR-Spektren von Pentafulvenen. (13C, 13C)-NMR-Kopplungskonstanten (1J(C,C))

Substituent Effects on NMR Spectra of Pentafulvenes. ¹³C, ¹³C-NMR Coupling Constants (¹J(C, C)) ¹H- and ¹³C-NMR spectra of 6-monosubstituted pentafulvenes 1 – 8 have been analysed, and ¹J(C, C) coupling constants have been determined from ID-inadequate spectra of ¹³C satellites. It turns out that ¹³C,¹³C coupling constants of the ring C-atoms, and especially J(1,2)/J(3,4) and J(2,3), reflect the extent of π delocalisation in the fulvene ring. With increasing electron-donating capacity of the substituent R, J(1,2)/J(3,4) values are decreasing, while J(2,3) (and J(1,5)/J(4,5) as well) are increasing, and linear correlations of Hammett substituent constants σ⁺ and ¹J(C,C) values are obtained.     

Thermische und photochemisch induzierte intramolekulare, 1,3-dipolare Cycloadditionen von 4-Phenyl-3-(2-allylphenyl)-sydnon. Vorläufige Mitteilung. 53. Mitteilung über Photoreaktionen

Thermal and photochemically induced intramolecular 1,3-dipolar cycloaddition reactions of 4-phenyl-3-(2-allylphenyl)-sydnone The title compound 9 was synthesised in the usual way, starting from 2-allylaniline and ethyl 2-bromo-2-phenylacetate, via the nitrosaminacid 8 (Scheme 2). 9 reacts at room temperature with its potential azomethinimine-function in an intramolecular [3+2]-cycloaddition to give the tricyclic compound 11 (Scheme 2). On irradiation, 9 yields the dihydro-3H-pyrazolo[2,3-a]indole 10 which probably arises by intramolecular [3+2]-cycloaddition of the corresponding intermediate nitrilimine.     

Kristallstruktur eines überbrückten 1,2,3-Oxadiazolidin-5-ons

The Crystal Structure of a Bridged 1,2,3-Oxadiazolidin-5-one Derivative 3-(2-Allylphenyl)-4-phenylsydnone ( 1 ) undergoes in solution an intramolecular, 1,3-dipolar cycloaddition reaction to give 2-oxo-1-phenyl-1,5-methano-1,2,4,5,6,11-hexahydro [1,2,3] oxadiazolo [3,2-a] cinnoline ( 2 ). The unique 1,2,3-oxadiazolidin-5-one structure of this molecule has been proved by X-ray analysis. The crystal structure has been solved by direct methods and refined by full-matrix least squares calculations to R = 0,046. The crystal system is orthorhombic, space group P_bca, with unit cell dimensions a = 10,546, b = 15,482, c = 16,531 Å.     

Fractal tiles associated with shift radix systems

Shift radix systems form a collection of dynamical systems depending on a parameter r which varies in the d-dimensional real vector space. They generalize well-known numeration systems such as beta-expansions, expansions with respect to rational bases, and canonical number systems. Beta-numeration and canonical number systems are known to be intimately related to fractal shapes, such as the classical Rauzy fractal and the twin dragon. These fractals turned out to be important for studying properties of expansions in several settings.In the present paper we associate a collection of fractal tiles with shift radix systems. We show that for certain classes of parameters r these tiles coincide with affine copies of the well-known tiles associated with beta-expansions and canonical number systems. On the other hand, these tiles provide natural families of tiles for beta-expansions with (non-unit) Pisot numbers as well as canonical number systems with (non-monic) expanding polynomials.We also prove basic properties for tiles associated with shift radix systems. Indeed, we prove that under some algebraic conditions on the parameter r of the shift radix system, these tiles provide multiple tilings and even tilings of the d-dimensional real vector space. These tilings turn out to have a more complicated structure than the tilings arising from the known number systems mentioned above. Such a tiling may consist of tiles having infinitely many different shapes. Moreover, the tiles need not be self-affine (or graph directed self-affine).     

First diastereoselective formation of lanthanide triple helical complexes with a terdentate chiral C2 symmetric ligand

Steric interactions between three enantiopure terdentate ligands leads to the diastereoselective formation of luminescent triple helical lanthanide complexes.