Synthesis and herbicidal activities of 7-azindolylpicolinic acids and their methyl esters derivatives

To discover picolinic acid molecules with excellent herbicidal activity, 22 new compounds of 4-amino-3,5-dicholo-6-(7-azindol-1-yl)-2-pyridinecarboxylic acids and their methyl esters derivatives were designed and synthesized. The inhibitory activities and potential herbicidal activities of the new compounds were preliminarily tested. It was found that the inhibitory activity of methyl esters on the root growth of Arabidopsis thaliana was generally better than that of corresponding picolinic acid compounds. All new compounds had good activity inhibiting Barnyard grass root growth through Petri dish test, and the pre-emergence herbicidal activity of compound VII-3 against A. retroflexus was more potent at 500 g/hm² than picloram, most of the compounds had the same herbicidal activity at 250 g/hm² against A. retroflexus and C. album planted in small pots in greenhouse as the control picloram, but they did not show pre/post-emergence herbicidal activity against barnyard grass.