SYNTHESIS AND STRUCTURE-ACTIVITY-RELATIONSHIPS OF HERBICIDAL THIOPHENE SULFONYLUREA COMPOUNDS

In a study of sulfonylurea herbicides, we found that some thiophene su lfonylureas, substituted at the 3 position and possessing the sulfonyl urea bridge at the 2 position of the thiophene ring, exhibit high herb icidal activities on paddy field application, Although most of them ar e phytotoxic to rice (Oryza sativa), introduction of a fluorine atom o nto the substituent attached at the 3 position of the thiophene moiety improved the selectivity to rice, Namely, 2,2-trifluoroethoxy)methyl} -2-thiophenesulfonamide and N-{(4, nocarbonyl}-3-{(2-fluoroethoxy)meth yl}-2-thiophene sulfonamide were selected as good herbicides for paddy field application.