SYNTHESIS AND HERBICIDAL ACTIVITY OF OPTICALLY-ACTIVE METHYL 3-HYDROXY-4-[4-[[5-(TRIFLUOROMETHYL)-2-PYRIDINYL]OXY]PHENOXY]PENTANOATES

Extensive field testing has shown methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]pentanoate to 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 8fold 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. © 1990, American Chemical Society. All rights reserved.