Synthesis and herbicidal activity of optically active methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]pentanoates
1990
Brown, R.W.
Extensive field testing has shown methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]pentanoate be a highly active postemergent herbicide. All four diastereomers were prepared separately, and their individual herbicidal activities were evaluated. The two diastereomers of R configuration at C-4 were found to be approximately twice as active as the racemic material and 8-fold more active than the corresponding S isomers. The absolute stereochemistry at C-3 had no effect on the biological activity. The dependence of the herbicidal activity on the absolute configuration at C-4 can be rationalized if methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]pentanoate is degraded in vivo to a 2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propionic acid derivative.
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