A facile synthesis and herbicidal activities of novel fluorine-containing thiazolo[4,5-d]pyrimidin-7(6H)-ones

Eighteen novel 5-alkylamino-6-aryl-3-phenyl-2-thioxo-2,3-dihydrothiazolo[4,5-d]pyrimidin-7(6H)-ones 5a-r were designed and easily synthesized via a tandem aza-Wittig reaction. Treatment of iminophosphorane 2 with aromatic isocyanate gave carbodiimide 3, which reacted with fluoro-substituted alkylamines to provide the title compounds in 65-87% isolated yields using sodium ethoxide as catalyst. All compounds 5 were confirmed by IR, ¹H NMR, MS and elemental analysis, and compound 5p was further analyzed by single-crystal X-ray diffraction. The preliminary bioassay indicated that some compounds showed significant inhibition activities against the root growth of rape and barnyard grass at a dosage of 100 mg/L.