0000000000347035
AUTHOR
Sabine Hinneschiedt
Gekreuzt konjugierte oligomere aus pyrrol-, benzol- und carbonyl-Bausteinen
Abstract Chalcones can serve as C 2 or C 3 components for the formation of 1 H -pyrroles. In particular the reaction with tosylisocyanid could be applied to the oligochalcones 2d - g with up to 6 enone units. A series of cross-conjugated oligomers 8d - g was obtained; these compounds consist of a chain of 1,4-phenylene, carbonyl and 1 H -pyrrole-3,4-diyl building blocks. The benzene rings bear two propoxy sidechains in order to enhance the solubility.
1,4-Benzoquinones with Styryl Substituents
2-Styryl-1,4-benzoquinone (1) and compounds 2 and 3 containing 1 as a substructure all proved to be highly reactive towards thermal or photochemical [4π + 2π] cyclodimerization reactions. Chemo-, regio- and stereoselective processes lead to dimers (compounds 1−10), which can undergo secondary reactions consisting of the addition of nucleophiles combined with a twofold keto-enol tautomerism (10 ⇄ 12). An alternative process is dehydrogenation/oxidation followed by an intramolecular [4π + 2π] cycloaddition (10 ⇄ 11). The same selective [4π + 2π] cyclodimerization can be observed in solution upon irradiation (e.g., 1a ⇄ 10a), in contrast to irradiation in the crystalline state which yields a […
Areno-Condensed 1,7,13-Triaza[18]annulenes
The 1,7,13-triaza[18]annulenes 9a−c were prepared by multi-step processes in which the final step consisted of a threefold cyclic condensation reaction of the Schiff bases 8a−c. Due to the length of the nine peripheral alkoxy chains, discotic liquid crystalline phases were obtained for 9b,c. The three nitrogen atoms in the central 18-membered ring not only permit protonation, but they can also serve for the complexation of NH4+ ions. The compounds 9a−c are highly photosensitive and exhibit crosslinking reactions on irradiation.