| abstract |
The present invention relates to a process for preparing 2-(aminomethylidene)-4,4-dihalo-3-oxobutyric esters of the formula (I), n nwherein R 1 , R 2 , R 3 are C 1 -C 6 -alkyl, C 1 -C 6 -haloalkyl, C 2 -C 6 -alkenyl, C 3 -C 10 -cycloalkyl or benzyl, and/or R 2 together with R 3 and the nitrogen atom to which the two radicals are attached are a heterocyclic radical, in which a corresponding 3-aminoacrylic ester is reacted with a halogen-substituted acetyl fluoride in the presence of at least one alkali or alkaline earth metal fluoride; and the further conversion of halogen-substituted 2-(aminomethylidene)-3-oxobutyric esters of the formula (I) to halomethyl-substituted pyrazol-4-ylcarboxylic acids and their esters. |