ANNONACEOUS ACETOGENINS FROM THE SEEDS OF ANNONA-SQUAMOSA - ADJACENT BIS-TETRAHYDROFURANIC ACETOGENINS

The petroleum ether extract of the seeds of Annona squamosa L. yielded thirteen adjacent and four non-adjacent bis-tetrahydrofuranic acetoge nins, in addition to squamocin (1) and squamostatin-A. The structures of the thirteen acetogenins, named as squamocins-B (2), -C (3), -D (4) , -E (5), -F (6), -G (7), -H (8), -I (9), -J (10), -K (11), -L (12), - M (13) and -N (14), have been established on the basis of spectral evi dence. Squamocins-B, -D, -E, -F, -I, -K and -N are new acetogenins. Th e structures of these acetogenins vary in the carbon number (C,, or C, ,), the number and position of hydroxyl groups (substituted at C-4, C- 12, C-28 or C-29) and the stereochemistry at the histetrahydrofuran mo iety. Squamocin-N (14) has an unprecedented threo-cis-threo-cis-threo eo stereochemistry in its bis-tetrahydrofuran portion. Co-occurrence o f a diastereoisomeric pair, 9 and 10, is noteworthy.