The reaction of sodium
cyanate with benzo[b]quinolizinium
substrates at room temperature gave 3-hydroxy-4-pyridyl-isoquinoline
derivatives in good yields. Presumably, the overall reaction proceeds
through an ANRORC-type sequence, that is, addition of
the nucleophile, ring opening,
and ring closure. Preliminary photophysical
investigation of the parent compound revealed a pronounced sensitivity
of its emission properties toward solvent effects and the pH of the
medium.
Irradiation of 2-benzoyl-N-benzylpyridinium derivatives and dimethyl acetylene dicarboxylate resulted in the formation of inolizine derivatives, one which was found to be the first example of a crystallochromic indolizine.
A disulfide-functionalized bis-benzo[b]quinolizinium is presented that is transformed quantitatively into its cyclomers in a fast intra-molecular [4+4] photocycloaddition. Both the bis-quinolizinium and the photocyclomers react with glutathione (GSH) or di-thiothreitol...
Dedicated to Professor Waldemar Adam on the occasion of his 85th birthdayA dinaphthoylmethyl-substituted bullvalene derivative is presented that exhibits excimer fluorescence. It is demonstrated that the fluxional bullvalene core supports the excimer formation of the aroyl substituents, thus offering the opportunity to monitor externally induced structural changes by fluorescence spectroscopy, as exemplarily shown by fluorimetric analysis of host-guest interactions of the diaroylbullvalene with metal cations, which lead to significant changes of the excimer emission. During the synthesis of the bullvalenes, it was discovered coincidentally that the corresponding triplet-sensitized photoreaction also yielded three unknown lumibullvalene isomers. The NMR-spectroscopic analysis of this reaction revealed a sequence and combination of different di-and tri-πmethane rearrangements and sigmatropic rearrangements. More importantly, the static lumibullvalenes proved useful as reference compounds for the evaluation of the emission properties of the fluxional bullvalenes.
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