INTERMEDIATES WITH BIOSYNTHETIC IMPLICATIONS IN DE-NOVO PRODUCTION OF PHENYL-PHENALENONE-TYPE PHYTOALEXINS BY MUSA-ACUMINATA - REVISED STRUCTURE OF EMENOLONE

Three new intermediates (1 - 3) in de novo biosynthetic pathway to phenyl-phenalenone-type phytoalexins have been isolated from rhizomes of Musa acuminata infected with the fungus Fusarium oxysporum. The structures of the new pre-phytoalexins were elucidated on the basis of spectroscopic evidences, chemical correlation and acid catalyzed biomimetic cyclization of 1 to emenolone (4), isolated from the same source and whose previously reported structure has been unambiguously corrected by X-ray diffraction analysis. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments (H-1 NMR, (1)3C NMR, COSY, ROESY, HMQC and HMBC).