SPONGIANE AND ENT-ISOCOPALANE DITERPENOIDS FROM THE MEDITERRANEAN SPONGE SPONGIA-ZIMOCCA

The Mediterranean sponge Spongia zimocca (Dictyoceratida) contains several spongiane and ent-isocopalane diterpenoids. Along with seven known compounds (1-6 and 11), four new diterpenoids, 12-deacecyl-aplysillin [13], 15-hydroxy-ent-isocopal-12-en-16-al [14], 15,17-diacetoxy-ent-isocopal-12-en-16-al [15] and 15,16-diacetoxy-11-oxo-ent-isocopal-12-ene [16], were isolated and characterized. The structures of the new compounds were determined mainly by spectroscopic methods and chemical correlation with known compounds. The absolute stereochemistry of 13 was assigned by applying Mosher's method, while those of 14 and 15 were suggested by ed comparison with polygodial [17] and 12-deacetoxyscalaradial [18].