Synthesis of (12R,13S)-pyriculariol and (12R,13S)-dihydropyriculariol revealed that the rice blast fungus, Pyricularia oryzae, produces these phytotoxins as racemates

Abstract Synthesis of assumed natural (12R,13S)-enantiomers pyriculariol (1) and dihydropyriculariol (2), phytotoxins isolated from rice blast disease fungus, Pyricularia oryzae, was achieved using Wittig reaction or microwave-assisted Stille coupling as the key step. The synthesis revealed that 1 2 are racemates. Foliar application test on a leaf indicated both salicylaldehyde core side chain were necessary for phytotoxic activity. fungus is found to produce optically active when incubated with rotary shaker, but racemic ones cultured an aerated jar fermenter.