New results on the mass spectra of cinchona alkaloids

Abstract

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.

Enantioselective Michael addition catalyzed by cinchona alkaloids

“…Dihydrocinchonidine (HCD) was prepared by hydrogenation of cinchonidine, 21 the preparation of O-acetylcinchonidine (AcOCD) was described elsewhere, 22 and O-methyldihydrocinchonidine (MeOHCD) was prepared as described. 23 Epiquinidine (EQD) was obtained by neutralization of an aqueous solution of epiquinidine hydrochloride kindly provided by Buchler GmbH.…”

Hydrogenation of cinchona alkaloids over supported Pt catalyst

“…The mass spectra were published and interpreted elsewhere. 33 The pure compounds were also analyzed by NMR spectroscopy. The 1 H, 13 C, and the 2D spectra were recorded on a Bruker AVANCE DRX-500 (Karlsruhe, Germany) spectrometer operating at 500 MHz 1 H-NMR frequency.…”

Heterogeneous asymmetric reactions. Part 24. Heterogeneous catalytic enantioselective hydrogenation of the C=N group over cinchona alkaloid modified palladium catalyst

“…Cinchonidine (CD, >98.0%), cinchonine (CN, >99.0%), quinine (QN, ∼99.0%), N-benzylcinchonidinium chloride (NBnCD + Cl − , >98%), N-benzylcinchoninium chloride (NBnCN + Cl − , >98%) were purchased from Fluka and used without further purification. Dihydrocinchonidine (HCD) was prepared by the hydrogenation of cinchonidine, 25 the preparation of O-acetylcinchonidine (AcOCD) was described elsewhere, 26 O-methyldihydrocinchonidine (MeOHCD), N-methylcinchonidinium chloride (NMeCD + Cl − ), and N-methylcinchonidinium iodide (NMeCD + I − ) were prepared by described procedures. 14 Cinchonidinium hydrochloride (CDH + Cl − ) was prepared from cinchonidine by titration with HCl solution.…”