1. Faulkner, D. J., Marine Natural Products, Nat. Prod. Rep.9 (1992) 323; and previous papers in the series.
2. Iguchi, K., Fujita, M., Nagaoka, H., Mitome, H., and Yamada, Y., Tetrahedron Lett.34 (1993) 6277.
3. The sponge was identified by Prof. R. W. M. van Soest, Institute of Taxonomic Zoology, University of Amsterdam. Specimens are deposited in his collection (registered number: ZMA Por. 7842).
4. Trade Mark; Shirasagi. For separation of 13.2 g of fraction 2, 60 g of the active carbon was used.
5. 2: [α]D+20.1°(c0.35, CHCl3). mp 204–205°C. CIMSm/z 497(M++1, C29H47 37ClO4+H), 495 (M++1, C29H47 35ClO4+H).