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

A new series of polychlorinated amino acid derivatives were isolated f rom the tropical marine sponge Dysidea herbacea (Dictyoceratida). Two major hexachlorinated metabolites, dysideathiazole (4) and N-methyldys ideathiazole (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 o f a Palauan specimen, together with the major metabolites 9,10-didechl oro-N-methyldysideathiazole (8) and 10-dechloro-N-methyldysideathiazol e (6). A second specimen from Palau contained dysideapyrrolidone (9). The structures of 4-9 were elucidated by spectroscopic methods. The ab solute stereochemistry of compounds 4-6 was determined by X-ray crysta llography of the natural products and of the carbamate derivative 17 t o be S at all chiral centers.