Abstract
Thirty-nine O-aryl O-ethyl N-sec-butylphosphoramidothioates were synthesized and tested for their antifungal activity against Pseudopernospora cubensis. Structure-activity relationship of various aryl substituents were examined. A 5-methoxy group on the 2-nitrophenyl moiety possessed an optimum van der Waals volume. A 4, 5-methylenedioxy substituent on the 2-nitrophenyl group was comparable to the most effective 5-methoxy group. A strong electron-withdrawing group on the 2-position, for instance a nitro group, was an important molecular requirement. Compounds with only a 3, 4-methylenedioxyphenyl or a 3, 5-dimethoxyphenyl group were also effective.
