Relationship between the structures of dihydrofuro- and dihydropyrano[2,3-b]quinolinium alkaloids, their spectral properties (ultraviolet absorption and fluorescence) and their chromatographic behaviour

Abstract

Chromophores of dihydrofuro-and dihydropyrano[2,3-b]quinolinium alkaloids differ from each other only by the position of the electron-donating substituents attached to the aromatic ring. It is shown that there is a connection between the electronic absorption and the fluorescence properties (taking advantage of solvent effects) and the chromophore structure of the alkaloids. The non-chromophore part of these structures also has an influence on the chromatographic behaviour of the molecules. It is shown that the spectral and chromatographic properties not only permit the identification of known structures but are also useful for predicting the structure of new quinolinium alkaloids. An example is given for two alkaloids isolated from Ptelea trifoliata(Rutaceae).