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Sponges, A plysina insularis, Bromoisoxazoline Alkaloids, Chemotaxonomy, Structure Elucidation An investigation of a specimen of the Caribbean sponge A plysina insularis resulted in the isolation of fourteen bromoisoxazoline alkaloids (1 -1 4 ), of which 14-oxo-aerophobin-2 (1)* is a novel derivative. Structure elucidation of the compounds have been established from spectral studies and data for 1 are reported. Constituents 2 to 6 and 11 to 14 have not been identified sofar in A plysina insularis species. The presence of the known compounds 7 to 9 in A plysina insularis indicates that their use for chem otaxonom ical purposes is questionable.

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Enantioselective Preparation and Enzymatic Cleavage of Spiroisoxazoline Amides.-The synthesis of various spiroisoxazoline amides (XII)-(XV) using similar technologies is presented, involving an enantioselective high pressure Diels-Alder cycloaddition of spiroisoxazoline (I) with chiral compound (II), asymmetric dihydroxylation, and enantioselective retro-Diels-Alder reaction as key step. Amides (XII)-(XV) are tested for their ability to serve as a substrate for an isoxazoline-splitting enzyme isolated from the marine sponge Aplysina cauliformis. It is shown that only compound (XII) is split quantitatively, while the other amides are no substrates for this enzyme. Thus, the presence of two bromine atoms, a free hydroxy group and a free N-H bond in the substrate are necessary for enzyme recognition. -(GOLDENSTEIN, KIM; FENDERT, THOMAS; PROKSCH, PETER; WINTERFELDT, EKKEHARD; Tetrahedron 56 (2000) 25, 4173-4185; Inst. Org. Chem., Univ. Hannover, D-30167 Hannover, Germany; EN)