Effects of stereoisomerisms on the electron ionization mass spectra and the IKE spectra of cinchona alkaloids.

Rapid Comm Mass Spectrometry

Kele

Sutyinszki

et al. 2004

The reaction mixture for the hydrogenation of ethyl pyruvate on Pt-alumina catalyst modified with isocinchona alkaloids (alpha-ICN (I) and beta-ICN (II)) was studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS). It was established that part of the chiral modifiers themselves are converted into ions of m/z 299, 305 and 309 in the course of chiral hydrogenation. The experimental data allowed the determination of the probable structure of the ions mentioned. According to ESI-MS/MS spectra the structure of the new cinchona alkaloids was assumed: tetrahydro-isocinchonines (III-VI), decahydro-isocinchonines (VII, VIII) and hydrogenated compounds of VII and VIII by scission of their C--N and C--O bonds (IX/1, IX/2, X). Fragmentation pathways are proposed for these new compounds.

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of chiral reactions: the structural detection of new hydrogenated isocinchona alkaloids from mixtures without isolation using electrospray ionization tandem mass spectrometry

Rapid Comm Mass Spectrometry

Kele

Sutyinszki

et al. 2004

“…The cinchona alkaloids have considerable pharmacological importance 1 and play a major role in asymmetric chemistry. [2][3][4][5][6] Although the mass spectra of parent cinchona alkaloids [cinchonidine (CD), cinchonine (CN), quinine (Q), quinidine (QD)] and related compounds obtained by electron impact (EI) [7][8][9][10] and chemical ionisation (CI) 11,12 have been reported, the mass spectra of other important cinchona alkaloids are not readily available. The study of the differences in the mass spectra of stereoisomeric compounds [13][14][15][16][17] with known structure can help to elucidate stereochemical problems in the asymmetric syntheses.…”

Section: Introductionmentioning

confidence: 99%

“…During the discussion of the experimental results only characteristic differences are mentioned, which proved to be novel compared to the behaviour of the parent cinchona alkaloids under similar conditions. Publications on the latter [7][8][9][10][11][12] give detailed informations on their fragmentation mechanisms as well.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectra of Iso-Cinchona- and Halogenated Cinchona Alkaloids

Eur J Mass Spectrom (Chichester)

Felföldi

Szőllősi

et al. 2000

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 C8-C9 bond. The fragmentation of the compounds containing C10-Br(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 C8-C9 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 C8-C9 bond. For the C10-Br(Cl) compounds, the primary fragmentations are the cleavage of the C9-O and C10-Br(Cl) bonds. Fragmentation pathways are discussed.

New results on the mass spectra of cinchona alkaloids

Szőllősi²,

Felföldi³

et al. 2000

J. Mass Spectrom.

The electrospray ionization (ESI) mass spectra of 16 cinchona alkaloid compounds were studied for the first time. The electron ionization (EI) spectra of 22 cinchona alkaloids were also recorded, 14 of which had not been examined previously. In the case of EI the characteristic direction of the fragmentation is the scission of the C8-C9 bond. Under EI the cleavage of the C4'-C9 bond occurs only in the case of hydrogenated cinchona alkaloids, whereas the C9-O bond cleavage can be observed in the case of ester and ether derivatives. At a low capillary exit voltage (CapEx) in the ESI measurements there is no fragmentation, and only the [M + H](+) and in some cases the double protonated [M + 2H](2+) ions can be detected. On increasing the CapEx the characteristic primary direction is the cleavage of the C9-O bond, which was observed in the case of epialkaloids and esterified or etherified cinchona derivatives, respectively. Copyright 2000 John Wiley & Sons, Ltd.