Synthesis and herbicidal activities of novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives

Three series of forty-nine novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives are designed, synthesized, and evaluated through a Spirodela polyrrhiza test and a greenhouse test. Some compounds show > 80% chlorophyll inhibition of Spirodela polyrrhiza at 10 μg/mL and exhibit some herbicidal activities against Digitaria adscendens in the pre-emergence treatment at a rate of 150 g/ha. Moreover, the study of the structure-activity relationship (SAR) suggests that the appropriate bulky substituent at the right position is critical for the bleaching and herbicidal activities, which may be useful for the future design of new compounds.