Process for the preparation of the herbicide ethyl alpha-2 dichloro-5 Ä4- (difluoro-methyl)Ü 4, 5-dihydro-3-methyl-5-o(oxo-ih-1, 2, 4-triazol-1-yl) -4-flurorbenzenepropanoate

摘要

There is disclosed a process for the preparation of a compound of formula (I): comprising: (i) forming a diazotized salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chl orophenyl)-1H-1,2,4-triazole by reacting a salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chl orophenyl)-1H-1,2,4-triazole with sodium nitrite; and (ii) simultaneously reacting said diazotized salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chl orophenyl)-1H-1,2,4-triazole, as it is produced in step (i), with ethyl acrylate in the presence of a Meerwein arylation catalyst to obtain a compound of formula (I).