脲嘧啶除草剂氟嘧硫草酯的合成研究

The synthese of herbicides tiafenacil

研究除草剂氟嘧硫草酯合成新方法。以邻氟苯胺为原料,经酰胺化、氯代反应制备化合物N-(4-氯-2-氟苯基)氨基甲酸乙酯;在碱的作用下,与3-氨基-4,4,4-三氟丁烯酸乙酯关环合成化合物3-(4-氯-2-氟苯基)-6-(三氟甲基)嘧啶-2,4(1H,3H)-二酮;经硫酸二甲酯甲基化,氯磺酸磺化,红磷/碘化钾/醋酸还原得到化合物(H)3-(4-氯-2-氟-5-巯基苯基)-1-甲基-6-(三氟甲基)-2,4(1H,3H)-嘧啶二酮;最后再与3-(2-氯丙酰氨基)丙酸甲酯缩合得到目标化合物氟嘧硫草酯,收率70.1%。该路线工艺简单,原料易得,为工业化生产奠定了基础。

This paper aims to study a new method for the synthesis of tiafenacil.N-(4-Chloro-2-fluorophenyl)ethyl carbamate was prepared from o-fluoroaniline through acylation and chlorination reactions.The compound 3-(4-chloro-2-fluorophenyl)6-trifluoromethyl-2,4(1H,3H)-pyrimidinedione was prepared through the cyclization reaction of ethyl 3-amino-4,4,4-trifluorobutyrate and N-(4-chloro-2-fluorophenyl)ethyl carbamate in the presence of base.Then it was methylated with dimethyl sulfate,sulfonated with chlorosulfonic acid,and reduced with red phosphorus/potassium iodide/acetic acid to give the compound of 2-chloro-4-fluoro-5-[3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl]phenyl mercaptan.Finally,2-chloro-4-fluoro-5-[3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl]phenyl mercaptan condensed with 3-(2-chloropropionylamino)propionic acid methyl ester to give the target compound tiafenacil,and the yield is 70.1%.The synthesis technology has advantages of simple operation and easily available raw materials,which lays the foundation for industrial production.