Synthesis and Biotransformation of Plausible Biosynthetic Intermediates of Salicylaldehyde-Type Phytotoxins of Rice Blast Fungus, Magnaporthe grisea

Rice blast fungus, Magnaporthe grisea, produces a series of salicylaldehyde‐type phytotoxins such as pyriculol, pyricuol, and pyriculariol. Plausible biosynthetic intermediates of these phytotoxins were synthesized in deuterium labeled forms using the Stille coupling reaction as the key step, and subjected to biotransformation by the fungus. Heptatrienylsalicylaldehyde was converted into dihydropyriculol by the fungus by a shaking culture. A new biosynthetic pathway comprising both oxidation and reduction is proposed. Heptatrienylsalicylaldehyde is proposed as the biosynthetic precursor of rice blast fungus phytotoxins. The synthesized compound in its deuterium labeled form was converted to dihydropyriculol by the fungus by a shaking culture.