Synthesis and herbicidal activity of aryloxyacetic acid derivatives as HPPD inhibitors

A series of aryloxyacetic acid derivatives were designed and synthesized as HPPD inhibitors. The preliminary bioassay results indicated that these derivatives displayed promising Arabidopsis thaliana HPPD ( At HPPD) inhibitory activity, such as compound I12 ( K i = 0.011 µ M) and compound I23 ( K i = 0.012 µ M), which were similar with commercial HPPD herbicide Mesotrione ( K i = 0.013 µ M). Furthermore, the newly synthesized compounds showed significant greenhouse herbicidal activities against tested weeds at dosages of 150 g ai/ha. In particular, compound II4 exhibited highly herbicidal activity for pre-emergence treatment, even better than those of Mesotrione. Besides, compound II4 was safe for weed control in maize fields at the rate of 150 g ai/ha. Therefore, compound II4 was identified as the most potent candidate for novel HPPD inhibitor herbicide. Compounds described herein might provide useful ideas in the design and modification of new HPPD inhibiting-based herbicides.