Oculatol, oculatolide, and A-nor sterols from the sponge Haliclona oculata

Chemical investigation of the marine sponge Haliclona oculata resulted in the isolation of eight new compounds including oculatol (1) and oculatolide (2) and six unusual A-nor steroids, 2-ethoxycarbonyl-2beta-hydroxy-A-nor-ergosta-5,24(28)-dien-4-one (3), 2-ethoxycarbonyl-24-ethyl-2beta-hydroxy-A-nor-cholesta-5-en-4-one (4), 2-ethoxycarbonyl-2beta,7beta-dihydroxy-A-nor-ergosta-5,24(28)-dien-4-one (5), 2-ethoxycarbonyl-2beta,7beta-dihydroxy-A-nor-cholesta-5-en-4-one (6), 2-ethoxycarbonyl-2beta,7beta-dihydroxy-24-methyl-A-nor-cholesta-5,22(E)-dien-4-one (7), and 2-ethoxycarbonyl-2beta,7beta-dihydroxy-A-nor-cholesta-5,22(E)-dien-4-one (8), along with 16 known steroids and indole derivatives. Their structures were unambiguously determined on the basis of extensive spectroscopic analyses.