Studies of the New Herbicide KIH-6127. Part III. Synthesis and Structure–Activity Studies of Analogues of KIH-6127 against Barnyard Grass (Echinochloa oryzicola)*

The previously evaluated prototype, methyl 6-acetyl-2-[(4,6-dimethoxypyrimidin-2-yl)oxy]benzoate, was modified by the introduction of an oximino group. Further extensive synthetic modifications were then made to the 6-alkyl moiety (R¹), the ester moiety (R²), the alkoxyimino moiety (R³), the bridge-atom (X) and the 4,6-disubstituted-pyrimidine moiety (A, B, Z). Structure–activity relationships of the synthesized compounds were studied by examining their herbicidal activity against Barnyard grass (Echinochloa oryzicola) in paddy rice at various growth stages, including pre-emergence. The novel herbicide methyl 2-[(4,6-dimethoxypyrimidin-2-yl)oxy]-6-[1-(methoxyimino)ethyl]benzoate, (KIH-6127) was found to be the most effective compound. The commercial development of this compound is currently in progress. © 1997 SCI.