Die Cardenolide von Parquetina nigrescens (A FZEL ) B ULLOCK 3. Mitt. Die Konstitution 5 neuer Cardenolide (16‐Dehydrostrophanthidin und verwandte Substanzen). Glykoside und Aglykone, 271. Mitteilung [1]

The structures of five new Cardenolides (A 1 , C, D, E, and K), isolated from Parquetina nigrescens , have been either partially or totally elucidated. Substance A 1 is 16β‐acetoxystrophanthidin 1 and substance C is 16‐dehydrostrophanthidin 4 . Substance D is a monodigitoxide of 16‐dehydrostrophanthidin whose structure is probably that shown in formula 7 . E was found to be a mixture of 16 ‐dehydrostrophanthidol 8 and the digitoxide of an unidentified genin. Substance K is probably the rhamnoside of 16‐acetoxystrophanthidin, whose structure is probably represented by 2 16‐dehydrostrophanthidol 8 which was used as a reference substance, was obtained by reduction of 16‐dehydrostrophanthidin 4 with NaBH 4 .