Synthesis, herbicidal activity, crop safety and soil degradation of sulfonylamino-substituted chlorsulfuron

Based on the splicing method of active substructures, four chlorsulfuron derivatives ( H01 - H04 ) were designed and synthesized by introducing different sulfonylamino groups on the 5-position of the benzene ring, which were confirmed with melting point, ¹H NMR, ¹³C NMR and HRMS. The preliminary biological activity test results showed that the 5-sulfonylamino-substituted compounds exhibited good herbicidal activities. At concentration of 150 g a.i/hm², the inhibition rates against Brassica napus of H01 , H02 and H04 were higher than 85% through pre-emergence treatment. In addition, the inhibition rates against Amaranthus retroflexus of H01 was 100%, which were better than chlorsulfuron (68.8%). For post-emergence treatment, the inhibition rates of H04 on B. napus and A. retroflexus were equivalent to that of chlorsulfuron. And the inhibition rates of H04 on Echinochloa crusgalli (85.2%) was better than that of chlorsulfuron (68.8%). The crop safety results indicated that the inhibition rates of these target compounds on the growth of wheat and corn were lower than that of chlrosulfuron. H01 and H04 showed safety to wheat growth through pre-emergence treatment. Additionally, the inhibition rates of H01 - H04 on corn were lower than chlorsulfuron. In the case of post-emergence treatment, H01 and H04 showed safety to corn. Alkaline soil (pH 8.39) degradation results indicated that the DT₅₀ (half-life of degradation) values of H01 - H04 varied from 44.43 to 53.32 days, which was shorter than that of chlorsulfuron (157.53 days). Based on the results, H01 and H04 could be used as potential sulfonylurea herbicides on wheat and corn. This paper could provide a reference for the further design of new sulfonylurea herbicides with high herbicidal activity, rapid degradation rate and superior crop safety.