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Rohrchen verschlossen, gut umgcschuttelt und in die Probe eingcfuhrt. Hei konstanter Tcinperatur wird der Silylbercich wiederholt in regelmassigen Zeitabstanden aufgcnommen. Da sich der Silylbereich der Isomeren 1 und 2 iiber 24 cps erstreckt (Bereich 250 cps, sweep time 250 Sck.), d.h. bei Aufnahme des ganzen Bereichs nur etwa alle 50 Sek. ein Messpunkt erhalten wird, wurdcii von 1 und 2 nur dic nahe beisarnmcnliegenden (10-12 cps) u n d gut ausgcbildetcn Signale (b) (vgl. Fig. l a ) aufgcnoinmen. Dic Abb. 4 zcigt den ganzen Silylmethylbereich dei-Isomeren 1 und 2. Durch Xusrncsscn dcr I'ik-Hohe konnten die jemeiligcn Konzentrationcn von 1 und 2 erhalten wertien. LITERATURVERZEICHNIS 229. CaZotuopis-Glykoside, vermutliche Teilstrukturl) Glykositle und Aglykone, 321. Mitteilungz) voii F. Bruschweiler, K. Stockel uiid T . Reichstein Institut fiir Organischc Chetnic d t r TTnivclrsitYt Easel (18. I S . 60)Summary. Reduction of uscharidin (19) with NaRH, gave a crystalline product C,,H,,O, which we formulate as /%tetrahydro-uschariclin (12), it was charactcrised as a crystalline tri-0-acetylderivative 14. The same compound 12 was obtained from calactin (18) and calotropin (18A), thus confirming carlier results of HESSE e2 al. about thc close interrelationship of the three compounds. New formulae are suggested for the 7 Calotropis glycosides: calactin (18), calotropin (ISA), uscharidin (19), calotoxin (20), procerosid (21), uscharin (31), and voruscharin (32). These formulae are consistent with the chemical reactions and spectra of the mentioned compounds. They are constructed in analogy t o the formula of gomphoside (11) advanced by WATSON et al. with only an additional oxo group at C-19.

The electron impact (EI) and field ionization (FI) mass spectra of some representative underivatized cardenolides have been studied together for the first time, with the objective of assessing the structural and in particular the sequence information afforded by this promising analytical method. Two series of cardenolides have been examined, each consisting of a mono-, di-and trisaccharide glycoside. The first was based on the aglycone digitoxigenin and comprised neriifolin, thevebioside and cerberoside; the second was based on the genin strophantidin and included cymarin, K-strophantin-@ and K-strophantoside. Other cardiac glycosides investigated and discussed include digitoxin and helveticoside. Important and structurally diagnostic fragmentations have been uncovered, especially in FI mode. In addition, thc EI and FI spectra of individual components of the cardenolides have been recorded, e.g. the genins digitoxigenin and strophantidin, and the monosaccharides L-thevetose, D-cymarose and D-glucose.

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