Abstract
We present an efficient approach to the chiral synthesis of podoblastins A, B and C, potent antifugal constituents obtained from Podophyllum peltatum L., against Pyricularia oryzae (rice blast). Optically pure podoblastins A, B and C ((6R)-(-)- and (6S)-(+)-3-acyl-5, 6-dihydro-6-propyl-2-pyrones) were synthesized from the corresponding, (R)-(-)- and (S)-(+)-glycerol derivatives, respectively, which are readily available as chirons. Both enantiomer of unnatural podoblastin S (3-decanoyl-5, 6-dihydro-6-propyl-2-pyrone), which are expected to reveal more effective antifungal activity than those of natural products, were also synthesized in the same manner. The synthesized compounds were tested against rice blast. The absolute stereochemistry of podoblastins A, B and C was confirmed to be (R). Synthetic compound, (R)-(-)-podoblastin S was the most effective in prevention.
