RESUMEN
All stereoisomers of 1,3-polyol/α-pyrone 1-8 with more than 99% ee were synthesized to estimate the effect of stereochemistry on the antifungal activity. The absolute configuration of natural compound was determined as (6R,2'S,4'R)-2. The eight stereoisomers showed the antifungal activity against plant pathogenic Alternaria alternata Japanese pear pathotype and Colletotrichum lagenarium. The large difference of activity level was not observed between stereoisomers, showing 43-72% of growth ratio against control at 0.5mM. The most potent stereoisomer was (6S,2'S,4'S)-8 and the activity of (6R,2'S,4'S)-1 was weakest against both fungi.
Asunto(s)
Colletotrichum/efectos de los fármacos , Plantas/microbiología , Polímeros/síntesis química , Polímeros/farmacología , Pironas/síntesis química , Pironas/farmacología , Antifúngicos/síntesis química , Antifúngicos/química , Antifúngicos/farmacología , Estructura Molecular , Polímeros/química , Pironas/química , EstereoisomerismoRESUMEN
Optically pure (+)- and (-)-boronolides were stereoselectively synthesized from yeast reductive products which had been obtained by yeast reduction of one common racemic substrate. The lactone structure of boronolide was constructed by Baeyer-Villiger oxidation. The stereochemistry of the yeast reduction products was studied to obtain the stereocenters at 5 positions of the dodecanolides of (+)- and (-)-boronolides. The stereochemistry of the 6 and 7 positions was obtained by AD-mix-α or ß oxidation. The chiral center at the 8 position was constructed by employing (R)-(+)- or (S)-(-)-2-methyl-CBS-oxazaborolidine reduction or the Mitsunobu reaction. The plant growth-inhibitory activity against Echinochloa crusgalli L. of naturally occurring (+)-boronolide was higher than that of the (-)-boronolide.