New azacyclopropene derivatives from Dysidea fragilis collected in Pohnpei.

The sponge Dysidea fragilis from Pohnpei contained four azacyclopropene derivatives, (4E)-S-dysidazirine [2], which is the optical enantiomer of the known compound dysidazirine [1], (4Z)-dysidazirine [3], (4E)-S-antazirine [4], and (4Z)-antazirine [5]. The structures of the new compounds were elucidated by interpretation of spectral data.