NEW POLYCHLORINATED AMINO-ACID DERIVATIVES FROM THE MARINE SPONGE DYSIDEA-HERBACEA

A new series of polychlorinated amino acid derivatives were isolated from the tropical marine sponge Dysidea herbacea (Dictyoceratida). Two major hexachlorinated metabolites, dysideathiazole (4) and N-methyldysideathiazole (5), and a minor pentachlorinated compound, 10-dechloro-N-methyldysideathiazole (6), were isolated from a specimen from Pohnpei. 10-Dechlorodysideathiazole (7) was isolated as a minor constituent of a Palauan specimen, together with the major metabolites 9,10-didechloro-N-methyldysideathiazole (8) and 10-dechloro-N-methyldysideathiazole (6). A second specimen from Palau contained dysideapyrrolidone (9). The structures of 4-9 were elucidated by spectroscopic methods. The absolute stereochemistry of compounds 4-6 was determined by X-ray crystallography of the natural products and of the carbamate derivative 17 to be S at all chiral centers.