Thiophen als Strukturelement physiologisch aktiver Substanzen, 8. Mitt. 1H,5H-Imidazo[1,2-a]thieno[3,4-d]pyrimidin-2(3H)-one

Thiophene as a Structural Element of Physiologically Active Compounds, VIII: 1H,5H-Imidazo[1,2-a]thieno[3,4-d]pyrimidin-2(3H)-ones The tricyclic title compound 1 can be synthesized in one step from the thiophene compounds 13 or 17 by base induced twofold ring closure.     

Über die boronierung von polystyrol

Boronic acid groups can be introduced in crosslinked and linear polystyrene by metalation with the complex butyllithium/N,N,N′,N′-tetramethylethylenediamine and subsequent treatment with boric acid esters. Investigations of the photochemical boronation of polystyrene by boron tribromid show that the reaction is accompanied by strong chain degradation, whereas the former method leads to an increase in molecular weight.     

Experimental models for the biological detection of N-nitroso compounds formed from amines and nitrite

The secondary and tertiary amines morpholine, aminopyrine and cimetidine as well as their nitroso products were examined for mutagenicity with the Ames Salmonella typhimurium microsome test (strains TA1535 and TA100) and the host-mediated assay. The formation of mutagenic nitroso compounds from morpholine and aminopyrine in the presence of nitrite could be demonstrated in artificial gastric juice and was confirmed in the stomach of mice in vivo. In contrast, the positive response of the chemical nitrosation in vitro with cimetidine did not match with the mammalian host-mediated assay results. To enhance sensitivity the role of modifiers of nitrosation, such as ascorbic acid and thiocyanate as well as the influence of biotransformation were studied.     

Untersuchungen zu den orientierungs- und dichtefluktuationen in amorphen polymeren mit hilfe der lichtstreuung

Using a light scattering photometer we investigated the orientation- and density fluctuations in the amorphous polymers “polycarbonate” (poly(oxycarbonyloxy-1,4-phenylene-isopropylidene-1,4-phenylene)) and polystyrene as a function of temperature. In addition to this, we performed supplementary measurements on oligomers of polystyrene and on the liquid-crystal compound 4-butyl-N-(p-methoxybenzyliden)aniline (MBBA) in the isotropic phase. From the amount of depolarized light scattering it is evident that an orientation correlation, as suggested for some bundle models, does not exist. As far as polystyrene is concerned, we were able to draw particularly detailed conclusions. The depolarized light scattering was constant in the whole angular range and independent of temperature. The anisotropy per monomeric unit of the oligomers already has a similar value to that of the polymer, consequently no additional orientation fluctuations are present in the polymer. The orientation correlation of the monomeric units in the polymer could be totally attributed to that in a random coil. The amount and temperature dependence of the light scattering of polystyrene caused by density fluctuations agreed with the results of the fluctuation theory. Consequently, light scattering due to density fluctuations of a specific macromolecular species did not occur.