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Eur. J. Mass Spectrom. 6, 347 - 355 (2000)

Mass spectra of iso-cinchona- and halogenated cinchona alkaloids

Tibor Bartók
Analytical Laboratory of Cereal Research Institute, PO Box 391, H-6701 Szeged, Hungary
Károly Felföldi
Department of Organic Chemistry, University of Szeged, H-6720 Szeged, Dóm tér 8, Hungary
György Szöllösi
Organic Catalysis Research Group of the Hungarian Academy of Sciences, H-6720 Szeged, Dóm tér 8, Hungary
Mih ly Bartók
Department of Organic Chemistry, University of Szeged, H-6720 Szeged, Dóm tér 8, Hungary, and Organic Catalysis Research Group of the Hungarian Academy of Sciences, H-6720 Szeged, Dóm tér 8, Hungary
Zofia Dega-Szafran and Jacek Thiel
Faculty of Chemistry, Adam Mickiewicz University, 60-780 Poznan, Poland

ABSTRACT:
The electron impact ionisation (EI) and electrospray ionisation (ESI) mass spectra using in-source collision-induced dissociation of nine different cinchona alkaloid derivatives [iso-cinchona alkaloids (ethereal isomers) and 10-Br(Cl) containing cinchona compounds] have been studied. In the case of the EI method for iso-cinchona alkaloids the observed fragmentation directions are as follows: isomerisation of the cyclic ethers to the corresponding C9 ketone, the formation of [M 15]+, [M 29]+ and [M 57]+ fragments as a result of the loss of methyl, ethyl and butyl radicals, and the cleavage of the C8C9 bond. The fragmentation of the compounds containing C10Br(Cl) bonds started with the scission of this bond. The primary bond rupture is followed by the fragmentation of the primary product into two parts across the C8C9 bond. In the case of the ESI method at low capillary exit voltage only the peak of the protonated molecule ([M + H]+), and in a significantly lower abundance, the peak of the [M + 2H]2+ ion can be observed. Increasing the capillary exit voltage causes fragmentation to occur. For iso-cinchona alkaloids the main direction is the cleavage of C8C9 bond. For the C10Br(Cl) compounds, the primary fragmentations are the cleavage of the C9O and C10Br(Cl) bonds. Fragmentation pathways are discussed.

Keywords: cinchona alkaloids, derivatives, structure elucidation, electron impact, electrospray

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