Herbizide Thienylharnstoffe,I

Summary Syntheses of the title substances as potential herbicides are described by a modified Curtius degradation of corresponding thiophene carboxylic acids, obtained in turn by haloform reaction of appropriate acetyl thiophenes. Regioselective substitution reactions of thiophenes were key steps for the construction of desired substitution patterns. Structure—activity considerations show that especially the 3-thienyl ureas36 and38 exhibit significant herbicidal activity comparable with commercial products.