Synthesis and evaluation of substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives as potent herbicidal agents.

In an attempt to obtain novel candidate compound for weed control, a series of newly substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives 2 were designed and synthesized using compound II7 as a lead compound by Intermediate Derivatization Methods and their herbicidal activities were evaluated. The herbicidal activity assay in greenhouse tests showed several compounds (2g, 2i, 2j, 2k, 2l, 2m, 2n and 2o) exhibited significant herbicidal activity for controlling velvet leaf (Abutilon theophrasti medic.) and youth-and-old age (Zinnia elegans jacq.) at 37.5ga.i./ha. In particular, 2h was found to be the most potential candidate herbicide and was proved higher activity than the lead compound II7. The result of the weed controlling spectrum test showed that 2h could effectively control dayflower (Commelina tuberosa), bur beggarticks (Bidens tripartita linn.), youth-and-old age, cassia tora (Cassiaobtusifolia L.), velvet leaf, purslane (Portulaca oleracea) and false daisy (Eclipta prostrata L.). In addition, the mixture of compound 2h and propanil could produce a synergistic effect and enhance herbicidal activity. The result of the herbicidal activity assay in field test demonstrated that 2h could effectively control dayflower and nightshade (Disambiguation) with long-lasting persistence. The present work indicates that 2h may be a novel compound candidate as a potential herbicide.

Design, synthesis, and herbicidal activity of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives.

A series of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives were designed and synthesized using 2-phenylpridines as the lead compound by intermediate derivatization methods in an attempt to obtain novel compound candidates for weed control. The herbicidal activity assay in glasshouse tests showed several compounds (II6, II7, II8, II9, II10, II11, III2, III3, III4, and III5) could efficiently control velvet leaf, youth-and-old age, barnyard grass, and foxtail at the 37.5 g/ha active substance. Especially, the activities of II6, II7, III2, and III4 were proved roughly equivalent to the saflufenacil and better than 95% sulcotrione at the same concentration. The result of the herbicidal activity assay in field tests demonstrated that II7 at 60 g/ha active substance could give the same effect as bentazon at 1440 g/ha active substance to control dayflower and nightshade, meanwhile II7 showed better activity than oxyfluorfen to control arrowhead and security to rice. The present work indicates that II7 may be a novel compound candidate for potential herbicide.

Solution-phase parallel syntheses of herbicidal 1-phenyl-2,4,5- imidazolidinetriones and 2-thioxo-4,5-imidazolidinediones.

In order to find new herbicidally active compounds, a fifteen-member library, focusing on the variation of 3- position substituents of 2,4,5-imidazolidine-trione or 2-thioxo-4,5-imidazolidinedione, was designed and prepared in parallel by the reaction of various ureas or thioureas with oxalyl chloride using solution-phase technology. An interesting and, to the best of our knowledge, unprecedented finding is that a by-product of 1-phenyl-3-propylcarbodiimide was formed during the addition of oxalyl chloride into the solution of 1-phenyl-3-propylthiourea in the presence of triethylamine in dichloromethane. It has been shown that the herbicidal activity of 2,4,5-imidazolidinetriones is about the same as that of their analogous 2-thioxo-4,5-imidazolidinediones. Compound with propyl or isopropyl group at the 3- position of 2,4,5-imidazolidinetrione ring demonstrated good herbicidal activity. The most active compound, 1-(2-fluoro- 4-chloro-5-propargyloxy)-phenyl-3-propyl-2-thioxo-4,5-imidazolidinedione, gave 95% control of the growth of velvetleaf at 200 g/ha in the post-emergence test.