Novel sulfonylurea derivatives containing five-membered heterocycle 3a—1 and 4a—d were synthesized in good yields by the regioselective addition of aryl sulfonylisocyanates 1 to 5-amino-3-benzyl(aryl) thio-1,2,4-triazoles and its pyrazole analogues 2. The structures of all these compounds were evaluated by elemental analyses and 1H NMR spectroscopy. The preliminary biological tests showed that the products displayed herbicidal activity against rape to some extent.
The herbicidal activities of a series of 1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonanilides containing various substituents on the benzene ring were quantitatively analyzed with physicochemi-cal parameters by using Hansch-Fujita method.Variations in the activity were parabolically related to electronic parameters with the optimum pKavalue being about 6.93.The hydrophobic factor in addition to the electronic property seemed to have important effect on the activity.
