1. F. Cafieri, L. De Napoli, E. Fattorusso, C. Santacroce and D. Sica, Tetrahedron Lett.1977, 477.
2. F. Cafieri, L. De Napoli, E. Fattorusso and C. Santacroce. Experientia33, 994 (1977).
3. Sponges, collected in the bay of Taranto, were obtained by Stazione di Biologia Marina del Salento, Porto Cesareo, Italy.
4. F. Cafieri, L. De Napoli, E. Fattorusso, C. Santacroce and D. Sica, Gazz. chim. ital.107, 71 (1977).
5. IR-spectra were recorded on a Perkin-Elmer 157 instrument.