Calotropis-Glykoside, vermutliche Teilstruktur.. Glykoside und Aglykone, 321. Mitteilung†‡

Reduction of uscharidin (19) with NaBH4 gave a crystalline product C29H42O9 which we formulate as β-tetrahydro-uscharidin (12), it was characterised as a crystalline tri-O-acetyl-derivative 14. The same compound 12 was obtained from calactin (18) and calotropin (18A), thus confirming earlier results of HESSEet al. about the close interrelationship of the three compounds. New formulae are suggested for the 7 Calotropis glycosides: calactin (18), calotropin (18A), 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 to the formula of gomphoside (11) advanced by WATSONet al. with only an additional oxo group at C-19.