1. E. Fattorusso, S. Magno, C. Santacroce andD. Sica, Tetrahedron28, 6021 (1972).
2. G. Cimino, S. De Stefano andL. Minale, Experientia29, 1063 (1973).
3. K. Hafizullah, A. Zamen, G. L. Chetty, A. S. Gupta andS. Dev, Tetrahedron Lett.1971, 4443.
4. G. Cimino, S. De Stefano, L. Minale andE. Fattorusso, Tetrahedron27, 4673 (1971).
5. Sponges, collected in the Bay of Naples, were obtained from the Supply Department of the Zoological Station (Naples) and identified by ProfessorN. Sarà and Dr.G. Pulitzer-Finali (University of Genoval) to whom the authors express their thanks.