With the aim of searching for highly bioactive urea-type cytokinins, eleven novel arylurea derivatives containing a 1,3,4-thiadiazole group were synthesized by the reaction of 2-amino-5-(E)-styryl- 1,3,4-thiadiazole with aroyl azides, which were efficiently prepared directly from their respective carboxylic acids, phosphorous oxychloride and sodium azide by one-pot procedure, then underwent a Curtius rearrangement upon heating to form the corresponding isocyanates. The structures of these title compounds were characterized by IR, ¹H NMR, MS techniques and elemental analysis, and the crystal structure of 3g was determined by X-ray single crystal diffraction method. The preliminary bioassay showed that some title compounds exhibit good cytokinin activity at the concentration of 10 mg/L, especially the promoting rate of compound 3c reach above 50%.

Key words: 1,3,4-thiadiazole, acyl azide, urea, synthesis, crystal structure, cytokinin