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

Three new intermediates (1 - 3) in de novo biosynthetic pathway to phe nyl-phenalenone-type phytoalexins have been isolated from rhizomes of Musa acuminata infected with the fungus Fusarium oxysporum. The struct ures of the new pre-phytoalexins were elucidated on the basis of spect roscopic 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 b y X-ray diffraction analysis. The chemical shift for all of the hydrog en and carbon atoms in the substances were unambiguously established b y mono- and bidimensional, homo- and heteronuclear NMR experiments (H- 1 NMR, (1)3C NMR, COSY, ROESY, HMQC and HMBC).