Synthetic Studies of Betaenones and Its Related Compounds

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The synthetic studies of biologically active compounds produced by phytopathogenic fungi are now useful for the structural confirmation, study of structure-activity relationship, suply of biosynthetic and metabolic intermediate and suply of bioactive natural products. Betaenones are phytotoxins isolated from culture filtrate of Phoma betae, causal fungus of leaf spot disease of sugar beet. On the biogenesis, betaenones are presumed to be derived through the intramolecular Diels-Alder reaction. Solanapyrones are phytotoxins of Alternaria solani, incitant of early blight disease on potato. Diplodiatoxin is a mycotoxin isolated from infected maize with Diplodia maydis which causes a well known disease, diplodiosis, among cattle and sheep in Southern Africa.Research achievements within two years are summarized as follows1. The first synthesis of betaenone C has been completed. This result has made possible to investigate further the structure-activity relationship and biosynthesis of the related compounds2. (<plus-minus>)-Solanapyrone A has been synthesized and the structure was unequivocally confirmig3. The stereochemistry of (+)-diplodiatoxin has been determined by the total synthesis.