1. G. Cimino, S. De Stefano andL. Minale, Tetrahedron28, 1315 (1972).
2. The sponge collected in the bay of Naples was obtained from the supply department of the Zoological Station (Naples) and identified by ProfessorM. Sarà (University of Genova), to whom the authors express their thanks.
3. UV-spectra were recorded in cyclohexane sclutions (unless otherwise indicated) with a Bausch and Lomb Spectronic 505 spectorphotometer. IR-spectra were determined in nujol with a Perkin-Elmer 257 Infracord spectrophotometer. NMR-spectra were recorded in CCl4 solutions on a Varian HA-100 apparatus operating at 100 MHz with TMS as internal standard. Mass spectra were recorded on an A.E.I. MS-9 spectrometer. Melting points, taken on a Kofler block, are uncorrected. All compounds gave satisfactory elementary analyses.
4. B. C. Das, M. Loveasmaa, C. Tendille andE. Lederer, Biochem. biophys. Res. Commun.21, 318 (1965).
5. A. Langemann andO. Isler, inBiochemistry of Quinones (Ed.R. O. Morton; Academic Press, London and New York 1965), p. 134.