Synthesis and herbicidal activity of 2-cyano-3-(2-fluoro-5-pyridyl)methylaminoacrylates

A series of 2-cyano-3-(2-fluoro-5-pyridyl)methylaminoacrylates were synthesized as herbicidal inhibitors of photosystem II (PSII) electron transport. 2-Fluoro-5-pyridinemethylamine was prepared from 2-amino-5-methylpyridine, subsequent reaction with 2-cyano-3,3-dimethylthioacrylates or 2-cyano-3-methoxyacrylates to yield these title compounds. All of these compounds were confirmed by 1H NMR, IR, mass spectrum and elemental analyses. Their herbicidal activities were evaluated. All of the title compounds showed excellent herbicidal activities to amaranth pigweed and rape in post-emergence treatment. At the rate of 150 g/ha, one compound exhibited similar activity to Cl-analogue. The replacement of chlorine by fluorine group showed the same herbicidal activity.