Synthesis and Herbicidal Activity of Diphenyl Ether Derivatives Containing Unsaturated Carboxylates

A series of novel diphenyl ether derivatives containing unsaturated carboxylates were designed and synthesized Their structures were identified by H-1 nuclear magnetic resonance and elemental analyses The bioassays indicated that the compounds 5b and 5c exhibited good herbicidal activities against velvetleaf at a concentration of 30-40 g/hm(2) The relationship between structure and herbicidal activity was also discussed Among unsaturated carboxylates group; butenoate is the most promising one Amonst them, 4-ethoxy-4-oxobutenyl 5-(2-chloro-4-(trifluoromethyl)phenoxy)-2-nitrobenzoate 5b was identified as the most promising candidate due to its high protoporphyrinogen IX oxidase inhibition effect (pI(50) = 6 64) and good herbicidal activity against broadleaf weeds with selectivity to soybean and low toxicity to mammals