cis-Enediyne chromophore of isano oil

The nonpolar fatty acids from isano oil have been reinvestigated to determine the source of the UV absorption long attributed to conjugatedcis-enediyne groupings. Proton magnetic resonance and mass spectra of certain fractions supported the occurrence of such structures, but discrete compounds with this grouping were not isolated. Part of this ubiquituous UV absorption ascribed to enediyne was found to be due instead to the same conjugated diynones identified previously in the oxygenated acid fraction of isano oil. The structures of methyl octadeca-9,11-diynoate and methyl isanate were correlated with their proton magnetic resonance, (PMR), carbon-13 magnetic resonance, and mass spectra.