Abstract
New Imidazole fungicides, OK-8705 (1-(4-methoxyphenoxymethyl)-2, 2-dimethylpropyl imidazole-1-carboxylate) and OK-8801 (the thiocarboxylate derivative of OK-8705), have one chiral center in the molecule. We determined the absolute configurations of the common starting material for synthesis of the fungicides, (-)- and (+)-1-(4-methoxyphenoxy)-3, 3-dimethyl-2-butanol, as (R)- and (S)-enantiomers, respectively, by Mosher's method. (R)- and (S)-OK-8705 and OK-8801 prepared from the (R)- and (S)-alcohols, respectively, were evaluated for their antifungal activity against Botrytis cinerea and Gibberella fujikuyoi using the agar dilution method. The antifungal activities of the (R)-isomers of OK-8705 and OK-8801 against B. cinerea were 513 and 265 times higher than those of the (S)-isomers, respectively; against G. fujikuyoi 38 and 143 times higher, respectively. We concluded that the (R)isomers were mainly responsible for the antifungal activity.
