Brasilenyne and cis -dihydrorhodophytin: Antifeedant medium-ring haloethers from a sea hare ( Aplysia brasiliana )

Brasilenyne and cis-dihydrorhodophytin: Antifeedant medium-ring haloethers from a sea hare (Aplysia brasiliana)

R. B. Kinnel*,
R. K. Dieter*,
J. Meinwald*,
D. Van Engen*,
J. Clardy*,
T. Eisner†,
M. O. Stallard‡, and
W. Fenical‡

^*Department of Chemistry, Cornell University, Ithaca, New York 14853
^†Section of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
^‡Scripps Institution of Oceanography, La Jolla, California 92093

Abstract

Two straight-chain C₁₅ fish antifeedants have been isolated from the sea hare Aplysia brasiliana. Chemical, spectral, and x-ray diffraction studies led to the characterization of these medium-ring ethers as brasilenyne (2) and cis-dihydrorhodophytin (3). The oxonin ring system of 2 is novel in nature. Biosynthetic considerations permit the postulation that a third compound, a noncrystalline congener of these compounds, is cis-isodihydrohodophytin (4).